Psoriasis
A chronic immune-mediated skin disease causing well-demarcated red, scaly plaques.
Overview
Psoriasis is a lifelong condition with relapses and remissions. It is more than skin-deep — psoriatic arthritis, cardiovascular risk and mental health impact are important. Treatments range from topical therapy to biologic agents.
Symptoms
- • Red plaques with silvery scale
- • Scalp, elbow and knee involvement
- • Nail pitting
- • Joint pain (psoriatic arthritis)
- • Itch
Risk factors
- • Family history
- • Smoking
- • Obesity
- • Stress
- • Beta-blockers, lithium (triggers)
Causes
- • Immune dysregulation (T-cell mediated)
- • Genetic predisposition (HLA-Cw6)
🚨 Red flags — seek urgent care
- • Generalised pustular psoriasis with fever — emergency
- • Erythroderma (whole-body redness)
- • New joint pain or swelling
When to seek care
- • Plaques affecting quality of life
- • Any joint symptoms
- • Failure of topical treatment
Diagnosis
- • Clinical — well-demarcated, erythematous, scaly plaques (extensors, scalp, sacrum)
- • Variants: plaque, guttate, flexural, pustular, erythrodermic; nail and joint involvement
- • Severity by PASI / BSA / DLQI
- • Screen for psoriatic arthritis annually (PEST tool)
Treatment
- • Mild–moderate: topical corticosteroid + vitamin D analogue (e.g. calcipotriol/betamethasone) once daily
- • Scalp: medicated shampoo + potent topical steroid scalp application
- • Phototherapy (NB-UVB) for extensive disease unresponsive to topicals
- • Systemic conventional: methotrexate, ciclosporin, acitretin
- • Biologics (anti-TNF, IL-17, IL-23) and oral targeted therapies (apremilast, JAK inhibitors) for severe disease
Prevention
- • No primary prevention; manage triggers (stress, infection, alcohol, lithium, beta-blockers)
- • Maintain healthy weight
- • Smoking cessation
- • Cardiovascular risk reduction
Complications
- • Psoriatic arthritis (up to 30%)
- • Cardiovascular disease, metabolic syndrome
- • Depression and reduced quality of life
- • Erythroderma — medical emergency
Education & self-care
This guidance is reviewed by Dr. Handel Emery, MD, FRCP (UK) and last updated 2026-06-08. It is educational and not a substitute for professional medical advice.
Frequently asked questions
Is psoriasis contagious?
No — it is an immune-mediated condition and cannot be spread from person to person.
Is psoriasis just a skin condition?
No — it is a systemic inflammatory disease. Up to 30% develop psoriatic arthritis, and the risk of cardiovascular disease, metabolic syndrome and depression is also higher.
When are biologics used?
When moderate-to-severe psoriasis fails to respond to topical treatment, phototherapy and standard systemic agents (methotrexate, ciclosporin), biologics targeting TNF, IL-17 or IL-23 are highly effective.
Can lifestyle changes help?
Yes — stopping smoking, reducing alcohol, weight loss in those with obesity, and treating depression all improve psoriasis severity and response to medication.