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Dermatology

Psoriasis

Psoriasis is a chronic immune-mediated inflammatory disease with several skin and nail phenotypes and important joint, psychological and cardiometabolic associations; severity depends on site, extent, symptoms and life impact, not redness alone.

Definition

Psoriasis is a chronic, relapsing immune-mediated inflammatory disease affecting skin and nails, with several phenotypes and important associations including psoriatic arthritis, psychological morbidity and cardiometabolic disease. Chronic plaque psoriasis is the commonest form, but pustular and erythrodermic presentations can be acute medical emergencies.

Epidemiology

Psoriasis affects about 2% of people in the UK and can begin at any age, with familial susceptibility common. Around 1 in 5 affected people develops psoriatic arthritis. Trauma, infection, smoking, alcohol and some medicines may influence disease expression, but no trigger is present in every person and flares should not be framed as personal failure.

Pathophysiology

Genetic and environmental factors alter innate and adaptive immune signalling, with dendritic cells, T cells and the TNF, IL-23 and IL-17 pathways interacting with keratinocytes. Accelerated proliferation and abnormal maturation produce epidermal thickening and parakeratotic scale, while inflammatory infiltrates and dilated superficial capillaries shape plaque colour and tenderness. This is a reciprocal network rather than a single fixed loop, which explains phenotypic diversity, variable treatment response and why skin severity cannot be inferred from erythema alone.

First principles

Psoriasis is an interacting immune and epidermal disorder, not one fixed loop

Genetic susceptibility and environmental exposures alter innate and adaptive immune signalling. Dendritic cells and T cells, particularly the IL-23 and Th17 axis, amplify TNF and IL-17 pathways; keratinocytes then proliferate, mature abnormally and release further inflammatory signals. This reciprocal network explains why both immune-directed and epidermis-directed treatments work, but no single cytokine or cell explains every phenotype, comorbidity or treatment response.1,2

Accelerated turnover creates scale, while inflammation shapes colour and thickness

Incomplete keratinocyte maturation produces parakeratosis and the sharply defined scale of a plaque. Epidermal thickening and dilated superficial capillaries contribute to elevation and erythema; pinpoint bleeding after scale removal is the Auspitz sign, but it is neither required nor diagnostic. On richly pigmented skin, active inflammation may appear violaceous, grey, brown or mainly as textural change, and post-inflammatory pigment alteration can outlast the active plaque.1,3

Different patterns reflect the same disease family but carry different risk

Chronic plaque psoriasis is common, but guttate, flexural, scalp, palmoplantar, nail, pustular and erythrodermic disease need different differentials and treatment choices. Trauma can produce lesions at injured sites through the Koebner phenomenon, and streptococcal infection can precede guttate psoriasis. Generalised pustular psoriasis and erythroderma can produce acute skin failure, infection risk and systemic disturbance, so they belong on a same-day specialist pathway rather than the routine topical ladder.3,1,4

Extent alone does not define disease burden

A small area on the face, genitals, palms, soles or nails can impair work, intimacy, mobility or self-image more than extensive covered plaques. Assessment therefore combines morphology, body surface area, high-impact sites, symptoms and quality of life. The same approach detects psoriatic arthritis, depression and cardiometabolic risk without implying that every person with limited psoriasis needs systemic investigations or treatment.3,1

Presentation

Chronic plaque psoriasis usually presents with sharply demarcated, raised scaly plaques on the elbows, knees, scalp, lumbosacral area or umbilicus, with possible nail change and inflammatory joint symptoms. Plaques may be pink or red on lighter skin but violaceous, brown, grey or predominantly scaly and thickened on darker skin.3,1,4

Cardinal features

  • Well-demarcated plaques with adherent white or silvery scale, often symmetrical on extensor sites
  • Scalp, post-auricular, umbilical, natal-cleft and lumbosacral involvement
  • Itch, soreness, fissuring or bleeding, with severity that may exceed the visible body surface area
  • Nail pitting, onycholysis, subungual hyperkeratosis or oil-drop discolouration
  • Koebner phenomenon, with new lesions at sites of trauma
  • Guttate disease with an acute crop of small scaly lesions, often after streptococcal infection
  • Flexural disease with smooth, sharply defined plaques and little scale
  • Psoriatic arthritis clues including inflammatory stiffness, swollen joints, dactylitis, enthesitis or inflammatory back pain

Red flags

  • Generalised pustular psoriasis, particularly widespread fresh pustules with fever, malaise, pain or systemic upset, needs immediate same-day specialist assessment and treatment
  • Erythroderma with widespread erythema, scaling, oedema, temperature disturbance, dehydration or haemodynamic compromise needs immediate same-day specialist assessment and treatment
  • Suspected sepsis, serious infection or acute skin failure requires urgent hospital assessment and stabilisation alongside dermatology review
  • New inflammatory joint, entheseal, dactylitic or axial symptoms need prompt rheumatology referral
  • Severe depression, self-harm thoughts or suicidal intent needs an urgent needs-based mental-health assessment
  • Diagnostic uncertainty, rapid atypical change or treatment-resistant disease should prompt reconsideration of infection, drug eruption, cutaneous lymphoma or another inflammatory dermatosis
  • Every child or young person with psoriasis should be referred to a specialist at presentation

Investigations

Clinical diagnosis with full skin, scalp and nail examination

Psoriasis is usually diagnosed from morphology, distribution and associated nail or joint features. Auspitz sign is not required. Examine high-impact sites including the face, scalp, palms, soles, flexures and genitals, and consider dermoscopy or biopsy only when the diagnosis remains uncertain.

Expected finding: A compatible psoriasis phenotype; erythema may be subtle or absent on Fitzpatrick skin types V and VI, while scale, thickness and pigment change remain evident.

3,1

Severity and life-impact assessment

At first presentation, before and at referral, and when judging treatment response, record static Physician Global Assessment, body surface area, nails, high-impact sites, systemic upset and physical, psychological and social impact. Use DLQI in adults or CDLQI in children when appropriate. PASI belongs mainly in specialist care, is not validated in children, and can underestimate erythema in Fitzpatrick skin types V and VI; adjust clinical interpretation for skin colour and for disability or communication needs.

Expected finding: Severity reflects extent, site, symptoms and impact; limited palmoplantar, facial, genital or nail disease can still be severe or functionally disabling.

3,5,6

Annual psoriatic arthritis assessment

Offer annual assessment to everyone with psoriasis, especially during the first 10 years after onset. Use a validated adult tool such as PEST, but ask separately about inflammatory back pain and axial symptoms because PEST does not detect axial arthritis. Refer to rheumatology as soon as psoriatic arthritis is suspected.

Expected finding: Peripheral inflammatory arthritis, dactylitis, enthesitis or axial symptoms may occur even when skin disease appears limited.

3

Comorbidity and psychological assessment

Ask about depression whenever severity and impact are assessed and when treatment is escalated. In adults with severe psoriasis, offer a validated cardiovascular risk assessment at presentation and every 5 years, or more often if the result indicates. Assess smoking, alcohol, weight and venous-thromboembolism risk in the usual clinical context rather than ordering a blanket metabolic panel for every person with psoriasis.

Expected finding: Modifiable cardiovascular risk, depression or harmful alcohol use may change treatment selection and follow-up.

3

Targeted tests for mimics or associated infection

Use skin or nail fungal microscopy and culture when dermatophyte infection is plausible, and biopsy persistent atypical or treatment-resistant plaques when cutaneous lymphoma or another diagnosis is possible. Consider streptococcal assessment when clinically indicated in acute guttate disease. Severe or atypical psoriasis is an HIV indicator condition, so offer testing according to the national HIV-testing pathway.

Expected finding: Testing is driven by the suspected alternative or trigger; routine blood tests do not confirm psoriasis.

3,1

Specialist pretreatment and monitoring assessment

Before phototherapy, conventional systemic treatment or targeted immunomodulation, document phenotype, severity score, quality-of-life score, previous adequate treatments, pregnancy plans, comorbidity, vaccination and infection risk. Baseline and follow-up tests are agent-specific: methotrexate, ciclosporin, acitretin, dimethyl fumarate, deucravacitinib and biologics do not share one universal monitoring schedule.

Expected finding: The specialist records treatment eligibility, contraindications, baseline safety results and the exact response and monitoring plan before initiation.

3,7,8,9,10,11,2

Management

StepDetailSource
Escalate acute pustular or erythrodermic disease immediatelyRefer generalised pustular psoriasis or erythroderma immediately for same-day specialist assessment and treatment. If there is fever, severe pain, systemic illness, dehydration, temperature disturbance, haemodynamic compromise or possible sepsis, arrange urgent hospital assessment and stabilisation rather than trying another outpatient topical. Assess airway, breathing, circulation, disability and exposure, fluid and temperature status, infection and medicines while involving dermatology; do not delay emergency care for a severity score.3NICE CG153, Psoriasis: assessment and management, 2012 (updated 2017)
Refer by age, diagnostic certainty, severity and joint riskRefer every child or young person with any psoriasis to a specialist at presentation. Refer an adult when the diagnosis is uncertain; disease is severe or extensive, for example more than 10% body surface area; topical treatment cannot control it; acute guttate psoriasis needs phototherapy; nail disease causes major functional or cosmetic impact; or physical, psychological or social impact is major. Refer to rheumatology as soon as psoriatic arthritis is suspected.3NICE CG153, Psoriasis: assessment and management, 2012 (updated 2017)
Make topical treatment practical and use corticosteroids safelyTopical treatment is first line, but offer phototherapy or systemic discussion at the same time when topical treatment is unlikely to control extensive, at least moderately severe or treatment-resistant-site disease. Choose a usable formulation, demonstrate amount and application, check adherence and review a new treatment after 4 weeks in adults or 2 weeks in children. Continuous potent or very potent corticosteroid can cause atrophy, striae, unstable psoriasis and systemic effects over large areas. Aim for a 4-week break between courses; do not use potent treatment continuously beyond 8 weeks or very potent treatment beyond 4 weeks. Never use a very potent corticosteroid in a child. Review adults using intermittent potent or very potent treatment, and children using any potency, at least annually. Emollients are adjuncts; warn that residue from paraffin-containing and paraffin-free products on clothing or bedding can ignite, including after washing.3,12,13NICE CG153, Psoriasis: assessment and management, 2012 (updated 2017); MHRA topical steroid and emollient safety updates
Use the adult trunk and limb topical sequence exactlyStart a potent topical corticosteroid once daily plus a vitamin D preparation or analogue once daily, applied separately morning and evening, for up to 4 weeks. If this has not produced satisfactory control by the formal maximum 8-week assessment point, stop the potent steroid and offer vitamin D or an analogue alone twice daily. If this remains unsatisfactory after 8 to 12 weeks, offer either a potent corticosteroid twice daily for up to 4 weeks or coal tar once or twice daily. Use fixed calcipotriol monohydrate with betamethasone dipropionate once daily for up to 4 weeks when twice-daily potent steroid or coal tar cannot be used, or when once-daily treatment would improve adherence. Very potent corticosteroid is adult specialist-only after other strategies fail, for no longer than 4 weeks; consider supported short-contact dithranol for resistant disease.3NICE CG153, Psoriasis: assessment and management, 2012 (updated 2017)
Keep paediatric trunk and limb treatment specialist-ownedFor a child or young person, specialist care may consider calcipotriol once daily only above age 6, or a potent topical corticosteroid once daily only above age 1. Product licences and safe treatment duration vary, so check the current BNFC and the selected product's SmPC. Do not use a very potent topical corticosteroid in anyone under 18.3NICE CG153, Psoriasis: assessment and management, 2012 (updated 2017)
Use the stepped scalp pathwayStart a potent topical corticosteroid once daily for up to 4 weeks and show how to apply it. If control is unsatisfactory, change formulation and/or remove adherent scale first with salicylic acid, an emollient or oil before another corticosteroid course. After a further 4 weeks without satisfactory control, offer fixed calcipotriol monohydrate with betamethasone dipropionate once daily for up to 4 weeks, or vitamin D once daily only when corticosteroid cannot be used and disease is mild to moderate. If up to 8 weeks of the combined product or vitamin D remains inadequate, offer an adult-only very potent corticosteroid up to twice daily for 2 weeks, coal tar, or specialist referral. Do not use coal-tar shampoo alone for severe scalp disease. For children, use current BNFC and product-specific age and duration advice.3NICE CG153, Psoriasis: assessment and management, 2012 (updated 2017)
Protect the face, flexures and genitalsUse a mild or moderate potency topical corticosteroid once or twice daily for no longer than 2 weeks. These sites are vulnerable to atrophy, so restrict corticosteroid exposure to 1 to 2 weeks per month and never use potent or very potent preparations there. In adults with inadequate response or a continuing need that creates serious steroid-toxicity risk, an experienced clinician may initiate an off-label topical calcineurin inhibitor twice daily for up to 4 weeks. Check paediatric duration and licensing in the current BNFC and product information.3,12NICE CG153, Psoriasis: assessment and management, 2012 (updated 2017)
Use phototherapy selectively and record cumulative exposureOffer narrowband UVB for plaque or guttate psoriasis that topical treatment cannot control. Two or three sessions weekly may be used; three times weekly can produce a faster response. Reconsider the modality when response or tolerance is poor, relapse exceeds 50% of baseline within 3 months, attendance is impractical or skin-cancer risk is high. Local PUVA may be considered for palmoplantar pustulosis. PUVA carries cumulative squamous-cell-carcinoma risk: avoid maintenance, record every exposure, avoid it in children when alternatives exist and arrange lifelong skin-cancer surveillance after more than 150 sessions or any treatment-associated skin cancer. Narrowband UVB can be used during pregnancy and breastfeeding; consider folate status when trying to conceive or after prolonged whole-body treatment.3,14NICE CG153, Psoriasis: assessment and management, 2012 (updated 2017); BAD and British Photodermatology Group NB-UVB guideline, 2022
Apply the conventional systemic eligibility test before choosing a drugSystemic treatment is specialist-owned. NICE requires failure of topical control, significant physical, psychological or social impact, and at least one of: extensive disease such as more than 10% body surface area or PASI above 10; localised disease causing functional impairment, high distress, high-impact-site disease or severe nail disease; or phototherapy that is ineffective, unavailable, contraindicated, intolerable or followed by relapse to more than 50% of baseline within 3 months. Select treatment with the person's age, phenotype, psoriatic arthritis, pregnancy plans, comorbidity, previous treatment and preference. Methotrexate is usual first choice; ciclosporin is a first choice when rapid or short-term control is needed, for palmoplantar pustulosis, or when systemic treatment cannot be avoided around conception; acitretin is an adult option when methotrexate and ciclosporin are unsuitable or ineffective or in pustular disease.3NICE CG153, Psoriasis: assessment and management, 2012 (updated 2017)
Make once-weekly methotrexate safety operationalMethotrexate for psoriasis is taken ONCE WEEKLY on the same named day, never daily; inadvertent daily dosing can cause fatal overdose. NICE gives an example starting schedule of 5 to 10 mg once weekly with gradual escalation to a maximum 25 mg once weekly, then the lowest effective dose. Assess response 3 months after reaching the target; inadequate response is failure to reach PASI 75 or PASI 50 plus a DLQI improvement of at least 5. Before treatment check FBC, renal and liver function, albumin, blood pressure and weight, infection status and pulmonary risk as indicated. Current SPS dermatology monitoring is commonly FBC, liver and renal tests every 1 to 2 weeks during the first month and until stable, then every 2 to 3 months; use the current specialist/local protocol because SPS notes pending alignment with newer BSR guidance. CG153 and SPS still name serial PIIINP in adult psoriasis, but local liver-fibrosis pathways vary; PIIINP is not suitable in children and is less reliable with psoriatic arthritis. Counsel about infection, cytopenia, liver and lung toxicity, drug interactions and sun protection.3,15,16,7,17NICE CG153, Psoriasis: assessment and management, 2012 (updated 2017); MHRA methotrexate safety updates; NHS Specialist Pharmacy Service monitoring guidance, updated 2026
Monitor ciclosporin and acitretin by their distinct risksFor ciclosporin, NICE starts at 2.5 to 3 mg/kg/day and allows increase to 5 mg/kg/day after 4 weeks if response is inadequate or rapid control is needed; assess after 3 months at the optimal dose, use the lowest effective dose and normally limit continuous treatment to 1 year. Obtain blood pressure and creatinine twice at baseline, then monitor renal function every 2 weeks for 3 months and monthly for the next 3 months; blood pressure and other safety tests are frequent during initiation and generally every 1 to 3 months when stable. Prescribe by brand and stop for uncontrolled hypertension. For acitretin, check liver function before treatment, every 1 to 2 weeks for 2 months and then about every 3 months; check fasting lipids before treatment, after 1 month and then every 3 months. Monitor mood and mucocutaneous toxicity. Follow the current specialist protocol and selected SmPC.3,8,9,18NICE CG153, Psoriasis: assessment and management, 2012 (updated 2017); NHS Specialist Pharmacy Service ciclosporin monitoring guidance, updated 2026; acitretin SmPC, updated 2026
Use current adult targeted options only after the NICE threshold is metFor adults with plaque psoriasis, the usual NICE technology-appraisal threshold is PASI at least 10 plus DLQI above 10, with inadequate response, contraindication or intolerance to conventional systemic treatments including methotrexate and ciclosporin and to phototherapy. Current options are deucravacitinib, apremilast, dimethyl fumarate; TNF inhibitors adalimumab, certolizumab pegol and etanercept; IL-17-pathway inhibitors bimekizumab, brodalumab, ixekizumab and secukinumab; IL-23 inhibitors guselkumab, risankizumab and tildrakizumab; and ustekinumab. Infliximab is reserved for very severe disease with PASI at least 20 and DLQI above 18. Use the least expensive suitable option after accounting for administration, dosage, commercial arrangements, psoriatic arthritis, inflammatory bowel disease, infection risk, previous malignancy, demyelination or heart failure, pregnancy and patient preference. Targeted treatment must be initiated and supervised by a consultant dermatologist experienced in its use.3,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,2,34NICE CG153 and NICE technology appraisals for targeted psoriasis treatment; BAD biologic therapy guidelines, 2020 and 2023
Apply each adult targeted treatment's own response timeDo not use a universal 16-week stop rule. Continue only with clear NICE-defined response, usually PASI 75 or PASI 50 plus a DLQI improvement of at least 5. Assess infliximab by week 10; etanercept, secukinumab, ixekizumab and brodalumab by week 12; and adalimumab, ustekinumab, apremilast, dimethyl fumarate, guselkumab, certolizumab pegol, risankizumab and bimekizumab by week 16. For tildrakizumab, consider stopping between weeks 12 and 28 if PASI 50 has not been reached, and stop at week 28 if response remains inadequate. For deucravacitinib, consider stopping between weeks 16 and 24 if PASI 50 has not been reached, and consider stopping at week 24 if response remains inadequate. Switch for primary or secondary failure or intolerance; seek supra-specialist advice after failure of 2 targeted agents. Adjust PASI interpretation for skin colour and DLQI interpretation for disability or communication needs.32,33,31,30,29,28,27,26,25,24,23,22,21,20,19,3NICE technology appraisals TA103, TA134, TA146, TA180, TA350, TA419, TA442, TA475, TA511, TA521, TA574, TA575, TA596, TA723 and TA907
Keep oral-targeted and biologic monitoring agent-specificApremilast requires baseline psychiatric and weight review; monitor for weight loss and new or worsening depression or suicidal thoughts, and stop for serious psychiatric symptoms. Dimethyl fumarate requires a current full blood count with differential before treatment and every 3 months; do not start with leukocytes below 3.0 x 10^9/L or lymphocytes below 1.0 x 10^9/L, monitor monthly if lymphocytes are 0.7 to below 1.0 x 10^9/L, and stop immediately if a repeat confirms below 0.7 x 10^9/L. Be alert for opportunistic infection and progressive multifocal leukoencephalopathy. Deucravacitinib needs infection and tuberculosis assessment and current vaccination review; it is a selective TYK2 inhibitor and should not automatically inherit every MHRA JAK-class restriction. Biologic baseline assessment generally covers tuberculosis, hepatitis, HIV when indicated, serious infection, vaccination and class-specific comorbidity; follow the chosen agent's SmPC and specialist protocol rather than a universal laboratory schedule.35,10,11,2,34MHRA apremilast safety update; Skilarence and Sotyktu SmPCs; BAD biologic therapy guideline
Use paediatric targeted treatment only within age-specific NICE pathwaysIn severe paediatric plaque psoriasis with PASI at least 10 after standard systemic treatment including methotrexate, ciclosporin and phototherapy has failed, is contraindicated or not tolerated, NICE options are adalimumab from age 4, etanercept from age 6, secukinumab from age 6 to 17 and ustekinumab from age 12. Stop etanercept and secukinumab at week 12, and adalimumab and ustekinumab at week 16, unless PASI 75 has been achieved. PASI is not validated in children, so the specialist must also account for skin colour, site, symptoms and impact. Do not extrapolate adult technology appraisals to children.5,6,3NICE TA455 and TA734, paediatric plaque psoriasis technology appraisals
Separate acute GPP treatment, medicine licensing and NHS fundingSame-day specialist or hospital care remains the first action for a generalised pustular psoriasis flare. NICE TA1070 recommends intravenous spesolimab for an initial moderate-to-severe adult flare when the Generalised Pustular Psoriasis Physician Global Assessment total is at least 3, the pustulation subscore is at least 2 with fresh pustules, and pustules with erythema involve at least 5% body surface area. For a subsequent flare after a previous spesolimab-treated flare resolved to pustulation 0 or 1, the pustulation subscore must be at least 2. A second dose may be given after 8 days if pustulation has not resolved to 0 or 1. The current intravenous SmPC licenses flare treatment from age 12, but TA1070 NHS funding is adult-only. NICE TA1144 made no recommendation for subcutaneous spesolimab flare prevention because the company did not submit evidence; do not present prevention or adolescent treatment as NICE-funded.4,36,37NICE TA1070, Spesolimab for treating generalised pustular psoriasis flares, 2025; Spevigo SmPC, updated 2026; NICE TA1144, 2026
Plan conception, pregnancy, breastfeeding and vaccination before treatmentAsk about pregnancy potential and plans before phototherapy or systemic treatment and coordinate specialist and obstetric advice. Methotrexate and acitretin are contraindicated in pregnancy; methotrexate is not recommended during breastfeeding, and post-treatment contraception intervals vary by current product information, so use the selected product's SmPC and BNF rather than one universal interval. Acitretin requires effective contraception from 1 month before treatment until 3 years after stopping, no alcohol in drinks, food or medicines during treatment and for 2 months afterwards in anyone who can become pregnant, and no blood donation for 3 years. Dimethyl fumarate is contraindicated in pregnancy and breastfeeding; avoid apremilast and preferably avoid deucravacitinib during pregnancy. Narrowband UVB is compatible with pregnancy and breastfeeding. If systemic treatment is essential, specialist options can include ciclosporin or certolizumab pegol; certolizumab is generally preferred when starting a biologic around conception because placental transfer is minimal. Maternal IgG biologics used beyond about 16 weeks may require the infant to avoid live vaccines for the first 6 months, depending on the agent; check the current SmPC. Review live vaccines before immunomodulatory treatment and do not give them during treatment when the agent prohibits this.2,3,18,9,17,10,11,14BAD biologic therapy guideline, 2020; NICE CG153; MHRA oral-retinoid pregnancy programme; current acitretin, dimethyl fumarate and deucravacitinib product information
Support long-term control without blame or unsafe medicine stoppingGive a written plan covering where and how long to use each topical, what to use during steroid breaks, when to review and which symptoms need same-day care. Discuss smoking cessation, weight, physical activity and alcohol according to individual risk, and treat depression or cardiovascular risk through the appropriate pathway. Review prescribed medicines that may worsen psoriasis, but do not tell a person to stop beta-blockers, lithium, antimalarials, corticosteroids or any essential medicine without the prescriber. Explain that flares are not personal failure, that post-inflammatory pigment change may persist after inflammation settles and that annual joint assessment remains necessary even when skin disease is controlled.3,1,13,16NICE CG153, Psoriasis: assessment and management, 2012 (updated 2017); BAD psoriasis overview

Illustrations

Well-demarcated plaque with silvery scale in psoriasisA sharply demarcated erythematous plaque surmounted by adherent silvery-white scale, characteristic of chronic plaque psoriasis.James Heilman, MD, Wikimedia Commons ยท CC-BY-SA-3.0
Epidermal turnover in psoriasisMicrograph of psoriasis showing epidermal hyperproliferation with parakeratosis, elongated rete ridges, dilated dermal capillaries and an immune infiltrate.Jenny Giang, Marc A. J. Seelen, Martijn B. A. van Doorn, Robert Rissma, Wikimedia Commons ยท CC-BY-4.0
Nail pitting in psoriasisClose-up photograph of nail pitting and onycholysis associated with psoriasis and psoriatic arthritis.Seenms, Wikimedia Commons ยท CC-BY-SA-3.0

Differentials

Atopic or discoid eczema

Usually more intensely itchy and poorly demarcated, with oozing or flexural predominance rather than sharply marginated extensor plaques; overlap can occur.

Seborrhoeic dermatitis

Greasy yellow-white scale in seborrhoeic sites with less sharply defined plaques; scalp and facial overlap with psoriasis can produce sebopsoriasis.

Dermatophyte infection

Annular advancing border, asymmetry or central clearing supports tinea; use fungal microscopy and culture when uncertain, especially before escalating corticosteroid.

Lichen planus

Pruritic violaceous flat-topped polygonal papules, Wickham striae and mucosal involvement distinguish it from a scaly psoriatic plaque.

Pityriasis rosea or secondary syphilis

A herald patch and cleavage-line eruption support pityriasis rosea; palm, sole, mucosal or systemic findings and sexual history should prompt syphilis testing rather than assuming guttate psoriasis.

Acute generalised exanthematous pustulosis or infection

A new medicine, abrupt febrile pustular eruption, neutrophilia, mucosal involvement or infectious focus may indicate AGEP or infection; widespread pustules still require same-day specialist assessment.

Cutaneous T-cell lymphoma

Persistent atypical, variably shaped or treatment-resistant patches and plaques, especially with poikiloderma or unusual distribution, require specialist review and biopsy.

Onychomycosis or traumatic nail dystrophy

Isolated asymmetric nail change, fungal debris or a trauma pattern favours an alternative; nail clippings or scrapings can prevent unnecessary psoriasis escalation.

Complications

  • Psoriatic arthritis with peripheral, entheseal, dactylitic or axial disease
  • Generalised pustular psoriasis or erythroderma with acute skin failure and systemic complications
  • Depression, anxiety, social isolation, self-harm risk and impaired quality of life
  • Cardiovascular and metabolic comorbidity, particularly in severe disease
  • Venous thromboembolism risk in adults, especially during admission, surgery or immobility
  • Treatment toxicity including topical corticosteroid atrophy, phototherapy-associated skin cancer and systemic medicine toxicity
  • Persistent post-inflammatory hyperpigmentation or hypopigmentation and functional impairment from palmoplantar or nail disease

Prognosis

Psoriasis usually follows a lifelong relapsing course, but topical therapy, phototherapy and systemic treatment can provide durable control. Outcome is improved by matching treatment to phenotype and life impact, detecting psoriatic arthritis promptly, managing cardiovascular and psychological risk, and preventing treatment toxicity. Pigmentary change can persist after active inflammation has settled.

Guidelines

  • Psoriasis: assessment and management (CG153) (NICE, 2012)
  • Deucravacitinib for treating moderate to severe plaque psoriasis (TA907) (NICE, 2023)
  • Spesolimab for treating generalised pustular psoriasis flares (TA1070) (NICE, 2025)
  • Guidelines for biologic therapy for psoriasis 2020 and 2023 updates (British Association of Dermatologists, 2023)

References

  1. British Association of Dermatologists, Psoriasis: an overview (Updated August 2023)
  2. British Association of Dermatologists guidelines for biologic therapy for psoriasis 2020: a rapid update (British Journal of Dermatology 2020;183:628-637)Published 1 Oct 2020
  3. NICE, Psoriasis: assessment and management, recommendations (CG153)Published 24 Oct 2012 | Updated 1 Sept 2017
  4. NICE, Spesolimab for treating generalised pustular psoriasis flares (TA1070)Published 18 Jun 2025
  5. NICE, Adalimumab, etanercept and ustekinumab for plaque psoriasis in children and young people (TA455)Published 12 Jul 2017
  6. NICE, Secukinumab for moderate to severe plaque psoriasis in children and young people (TA734)Published 7 Oct 2021
  7. NHS Specialist Pharmacy Service, Methotrexate monitoring (SPS medicines monitoring)Published 5 Jul 2021 | Updated 7 Jan 2026
  8. NHS Specialist Pharmacy Service, Ciclosporin monitoring (SPS medicines monitoring)Updated 7 Jan 2026
  9. Electronic Medicines Compendium, Acitretin 25 mg capsules summary of product characteristics (Acitretin SmPC)Updated 12 Jun 2026
  10. Electronic Medicines Compendium, Skilarence summary of product characteristics (Dimethyl fumarate SmPC)Updated 8 Oct 2024
  11. Electronic Medicines Compendium, Sotyktu summary of product characteristics (Deucravacitinib SmPC)Updated 9 Aug 2024
  12. MHRA, Topical steroids: new labelling and reminder of severe adverse effects including withdrawal reactions (Drug Safety Update)Published 29 May 2024
  13. MHRA, Emollients: severe and fatal burns with paraffin-containing and paraffin-free products (Drug Safety Update)Published 18 Dec 2018 | Updated 26 Aug 2020
  14. British Association of Dermatologists and British Photodermatology Group guidelines for narrowband ultraviolet B phototherapy 2022 (British Journal of Dermatology 2022;187:295-308)Published 1 Sept 2022
  15. MHRA, Methotrexate once weekly: measures to reduce fatal overdose from inadvertent daily dosing (Drug Safety Update)Published 23 Sept 2020
  16. MHRA, Methotrexate: precautions in the sun to avoid photosensitivity reactions (Drug Safety Update)Published 30 Aug 2023
  17. British Association of Dermatologists, Methotrexate patient information leaflet (Updated August 2025)
  18. MHRA, Oral retinoid medicines: revised pregnancy-prevention educational materials (Drug Safety Update)Published 19 Jun 2019
  19. NICE, Deucravacitinib for treating moderate to severe plaque psoriasis (TA907)Published 28 Jun 2023
  20. NICE, Bimekizumab for treating moderate to severe plaque psoriasis (TA723)Published 1 Sept 2021
  21. NICE, Risankizumab for treating moderate to severe plaque psoriasis (TA596)Published 21 Aug 2019
  22. NICE, Tildrakizumab for treating moderate to severe plaque psoriasis (TA575)Published 17 Apr 2019
  23. NICE, Certolizumab pegol for treating moderate to severe plaque psoriasis (TA574)Published 17 Apr 2019
  24. NICE, Guselkumab for treating moderate to severe plaque psoriasis (TA521)Published 13 Jun 2018
  25. NICE, Brodalumab for treating moderate to severe plaque psoriasis (TA511)Published 21 Mar 2018
  26. NICE, Dimethyl fumarate for treating moderate to severe plaque psoriasis (TA475)Published 6 Sept 2017
  27. NICE, Ixekizumab for treating moderate to severe plaque psoriasis (TA442)Published 26 Apr 2017
  28. NICE, Apremilast for treating moderate to severe plaque psoriasis (TA419)Published 23 Nov 2016
  29. NICE, Secukinumab for treating moderate to severe plaque psoriasis (TA350)Published 22 Jul 2015
  30. NICE, Ustekinumab for treating moderate to severe plaque psoriasis (TA180)Published 23 Sept 2009 | Updated 3 Mar 2017
  31. NICE, Adalimumab for treating moderate to severe plaque psoriasis (TA146)Published 25 Jun 2008
  32. NICE, Etanercept for treating moderate to severe plaque psoriasis (TA103)Published 26 Jul 2006 | Updated 1 Sept 2009
  33. NICE, Infliximab for treating moderate to severe plaque psoriasis (TA134)Published 23 Jan 2008
  34. British Association of Dermatologists guidelines for biologic therapy for psoriasis 2023: a pragmatic update (British Journal of Dermatology 2024;190:270-272)Published 22 Sept 2023
  35. MHRA, Apremilast: risk of suicidal thoughts and behaviour (Drug Safety Update)Published 19 Jan 2017
  36. Electronic Medicines Compendium, Spevigo intravenous summary of product characteristics (Spesolimab SmPC)Updated 14 May 2026
  37. NICE, Spesolimab for preventing generalised pustular psoriasis flares, terminated appraisal advice (TA1144)Published 8 Apr 2026

Evidence checked: 2026-08-03

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.