PassFinals
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.

In a nutshell

Psoriasis is a chronic immune-mediated inflammatory disease with plaque, guttate, flexural, scalp, nail, pustular and erythrodermic phenotypes. Diagnose clinically, assess site, extent, impact, joints and comorbidity, and use the correct site-specific topical sequence; generalised pustular psoriasis and erythroderma need same-day specialist treatment.

Classic presentation

A person has symmetrical, sharply demarcated scaly plaques on extensor elbows and knees or the scalp, with possible nail pitting; on darker skin the inflammation may look violaceous, brown or grey rather than bright red.

Key points

  • Auspitz sign is supportive at most and is neither required nor confirmatory; biopsy is reserved for diagnostic uncertainty.
  • Record body surface area, static PGA, nails, high-impact sites, systemic upset and DLQI or CDLQI; PASI may underestimate erythema in Fitzpatrick skin types V and VI and is not validated in children.
  • Offer annual psoriatic arthritis assessment to everyone, use PEST in adults but ask separately about axial symptoms, and refer to rheumatology as soon as inflammatory joint disease is suspected.
  • Refer every child or young person at presentation. Refer adults for diagnostic uncertainty, severe or extensive disease, failed topical control, phototherapy-requiring guttate disease, major nail impact or major life impact.
  • Potent topical corticosteroid plus vitamin D at separate times is the initial adult trunk and limb regimen; fixed calcipotriol with betamethasone is a later adherence option, not a generic first-line substitute.
  • Aim for a 4-week break between potent or very potent corticosteroid courses. Do not use potent steroid continuously beyond 8 weeks, very potent beyond 4 weeks, very potent in children, or potent or very potent steroid on the face, flexures or genitals.
  • Methotrexate for psoriasis is ONCE WEEKLY on a named day, never daily; daily dosing can be fatal.
  • Targeted adult options and stopping times are agent-specific. Infliximab also has a higher entry threshold of PASI at least 20 and DLQI above 18.
  • The intravenous spesolimab licence includes age 12 and over, but NICE TA1070 funds qualifying GPP flares in adults only; NICE has not recommended subcutaneous flare prevention.
  • Methotrexate and acitretin are contraindicated in pregnancy. Acitretin pregnancy prevention continues for 3 years after stopping. Plan infant live vaccines when a placentally transferred biologic continues later in pregnancy.

First-line investigation

No routine test confirms psoriasis: examine the entire skin, scalp and nails, record severity and impact, ask about inflammatory joint symptoms and use targeted fungal testing or biopsy only when the differential requires it.

Management

Recognise acute skin failure and urgent mental-health risk

  • Generalised pustular psoriasis and erythroderma require immediate same-day specialist assessment and treatment. Fever, systemic illness, dehydration, temperature disturbance, haemodynamic compromise or suspected sepsis needs urgent hospital stabilisation as well as dermatology input.3,4
  • Severe depression, self-harm thoughts or suicidal intent requires urgent needs-based mental-health assessment; visible body surface area does not predict psychological risk.3,1

Assess severity, joints, comorbidity and referral need

  • Record phenotype, static PGA, body surface area, nails, face, scalp, palms, soles, flexures and genitals, systemic upset and DLQI or CDLQI. Adjust PASI interpretation for skin colour; PASI and body surface area are not validated in children.3,5,6
  • Offer annual psoriatic arthritis assessment to everyone, especially in the first 10 years. PEST is an adult tool and misses axial disease, so ask about inflammatory back pain; refer to rheumatology as soon as psoriatic arthritis is suspected.3
  • Refer every child or young person at presentation. Refer adults for uncertainty, more than 10% body surface area or other severe disease, failed topical control, guttate disease needing phototherapy, major nail impact or major physical, psychological or social impact.3
  • In adults with severe psoriasis, assess cardiovascular risk at presentation and every 5 years or sooner if indicated. Ask about depression whenever severity is assessed or treatment escalates.3

Use the site-specific topical ladder

  • Adult trunk or limbs: potent corticosteroid once daily plus vitamin D or analogue once daily at separate times for up to 4 weeks. If inadequate, move through vitamin D twice daily, then after 8 to 12 weeks potent corticosteroid twice daily for up to 4 weeks or coal tar. Fixed calcipotriol with betamethasone once daily for up to 4 weeks is used when twice-daily treatment cannot be used or adherence improves.3
  • Scalp: potent corticosteroid once daily up to 4 weeks; if inadequate, change formulation and/or descale before another course. Next use fixed calcipotriol with betamethasone, or vitamin D only for mild-to-moderate disease when steroid cannot be used; persistent disease needs the adult-only 2-week very-potent option, coal tar or specialist referral.3
  • Face, flexures or genitals: mild or moderate corticosteroid once or twice daily for no more than 2 weeks and only 1 to 2 weeks per month. Never use potent or very potent steroid there; an adult expert may initiate off-label topical calcineurin inhibitor twice daily for up to 4 weeks.3,12
  • Aim for a 4-week break between potent or very potent courses. Maximum continuous use is 8 weeks for potent and 4 weeks for very potent treatment; no very potent steroid in children. Review a new topical after 4 weeks in adults and 2 weeks in children.3,12
  • Paediatric trunk or limb treatment is specialist-owned: consider calcipotriol once daily only over age 6 or potent corticosteroid once daily only over age 1, with current BNFC and product-specific licensing and duration checks.3

Escalate to phototherapy or conventional systemic treatment

  • Offer narrowband UVB for plaque or guttate psoriasis uncontrolled by topicals, commonly 2 or 3 times weekly. Avoid maintenance; document cumulative PUVA exposure and remember its dose-related skin-cancer risk.3,14
  • Systemic eligibility needs failed topical control, significant life impact and extensive disease, localised high-impact or function-limiting disease, or ineffective, unavailable, intolerable or rapidly relapsing phototherapy. It is not based on body surface area alone.3
  • Methotrexate is usual first choice; ciclosporin is preferred for rapid or short-term control, palmoplantar pustulosis or when systemic treatment cannot be avoided around conception; acitretin is an adult alternative when those are unsuitable or for pustular disease.3
  • Methotrexate is ONCE WEEKLY on one named day, never daily. NICE gives 5 to 10 mg once weekly initially with gradual increase to a maximum 25 mg once weekly; inadvertent daily dosing can be fatal. Use the current specialist monitoring protocol.3,15,7

Apply targeted eligibility and stopping rules

  • At PASI at least 10 plus DLQI above 10 after conventional systemic treatment and phototherapy fail or cannot be used, adult NICE options are deucravacitinib, apremilast, dimethyl fumarate, adalimumab, certolizumab, etanercept, bimekizumab, brodalumab, ixekizumab, secukinumab, guselkumab, risankizumab, tildrakizumab and ustekinumab. Infliximab requires PASI at least 20 plus DLQI above 18.3,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33
  • Adult stopping times: infliximab 10 weeks; etanercept, secukinumab, ixekizumab and brodalumab 12 weeks; adalimumab, ustekinumab, apremilast, dimethyl fumarate, guselkumab, certolizumab, risankizumab and bimekizumab 16 weeks. Adequate response is usually PASI 75 or PASI 50 plus DLQI improvement of at least 5.32,33,31,30,29,28,27,26,25,24,23,21,20
  • Tildrakizumab: consider stopping at 12 to 28 weeks without PASI 50, and stop at 28 weeks if still inadequate. Deucravacitinib: consider stopping at 16 to 24 weeks without PASI 50, and consider stopping at 24 weeks if still inadequate.22,19
  • Paediatric NICE options after standard systemic failure are adalimumab from age 4, etanercept and secukinumab from age 6, and ustekinumab from age 12. Require PASI 75 at 12 weeks for etanercept or secukinumab and 16 weeks for adalimumab or ustekinumab.5,6
  • A qualifying adult GPP flare may receive intravenous spesolimab under TA1070. Although the current licence includes age 12 and over, NHS TA1070 funding is adult-only, and TA1144 does not recommend subcutaneous flare prevention.4,36,37

Protect pregnancy, breastfeeding, vaccines and monitoring

  • Methotrexate and acitretin are contraindicated in pregnancy; acitretin contraception continues for 3 years after stopping. Methotrexate post-treatment intervals are product-specific. Dimethyl fumarate is contraindicated in pregnancy and breastfeeding; avoid apremilast and preferably deucravacitinib during pregnancy.17,18,9,10,11
  • Narrowband UVB is compatible with pregnancy and breastfeeding. If systemic treatment is essential, specialist options include ciclosporin or certolizumab; certolizumab has minimal placental transfer. Later-pregnancy exposure to other IgG biologics may require avoidance of infant live vaccines for 6 months, depending on the agent.14,2,3
  • Methotrexate, ciclosporin, acitretin, dimethyl fumarate, deucravacitinib and biologics have different baseline tests, laboratory intervals, infection risks and vaccine rules. Use the current SmPC and specialist protocol, not one universal monitoring schedule.7,8,9,10,11,2

Maintain control and safety-net

  • Give a written topical plan, annual joint assessment and a clear route back to care. Widespread pustules, near-total erythema, fever, systemic illness or rapid deterioration needs same-day assessment.3,4
  • Warn that all emollient residues can accelerate fire. Keep treated clothing and bedding away from smoking and naked flames; washing does not remove the risk completely.13
  • Review possible medicine triggers with the prescriber but never advise abrupt self-discontinuation of an essential medicine. Address smoking, alcohol, weight, cardiovascular risk and depression without implying that a flare is the person's fault.3,1

Exam traps

  • Generalised pustular psoriasis and erythroderma are same-day specialist problems, not routine topical-treatment failures.
  • Every child or young person with psoriasis is referred at presentation, even when disease appears limited.
  • A fixed calcipotriol and betamethasone product is a later once-daily adherence option in the NICE adult trunk and limb ladder, not the default initial substitute for separately timed treatments.
  • PEST does not detect axial arthritis or inflammatory back pain.
  • PASI may underestimate erythema in darker skin and is not validated in children; high-impact-site disease can be severe despite a low body surface area.
  • Methotrexate is once weekly on a named day. Daily dosing can be fatal.
  • Do not use a universal 16-week biologic stop rule: adult assessment ranges from 10 to 28 weeks by agent.
  • Infliximab uses the higher NICE threshold of PASI at least 20 and DLQI above 18.
  • Spesolimab's licence includes adolescents, but NICE TA1070 GPP-flare funding is adult-only and TA1144 does not recommend routine flare prevention.
  • Acitretin pregnancy prevention continues for 3 years after stopping; methotrexate intervals depend on the current selected product information.
  • Do not tell someone to stop a prescribed beta-blocker, lithium, antimalarial or corticosteroid without the responsible prescriber.

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 · 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 · CC-BY-4.0
Nail pitting in psoriasisClose-up photograph of nail pitting and onycholysis associated with psoriasis and psoriatic arthritis.Seenms, Wikimedia Commons · CC-BY-SA-3.0

Key sources

  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

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.