Synopsis
Distinguish three common psoriasis phenotypes, assess severity and whole-person impact, recognise instability, and choose site-appropriate first treatment and referral without relying on erythema alone.
- Chronic plaque psoriasis produces persistent, well-demarcated scaly plaques, classically on extensor elbows and knees, scalp, sacrum and umbilicus; colour may be red, violaceous, brown or grey according to skin tone.
- Guttate psoriasis is an acute shower of small scaly papules, often one to three weeks after streptococcal pharyngitis; inspect the throat but do not promise that antibiotics will clear the eruption.
- Flexural psoriasis is smooth, sharply bordered and minimally scaly in axillae, groin, inframammary folds or natal cleft; exclude candidiasis, dermatophyte infection and contact irritation when atypical.
- Record patient and clinician global severity, body surface area, difficult sites, nail disease, systemic upset, life impact and joint symptoms; erythema can be underestimated in deeply pigmented skin.
- Topical treatment is first-line for most limited disease, but formulation and potency must follow site: thick trunk plaques tolerate different therapy from face, flexures and genitals.
- Refer for diagnostic uncertainty, more than 10% body surface area, inadequate topical control, major functional or psychosocial impact, phototherapy need, significant nails, or any childhood psoriasis.
- Generalised pustular psoriasis or erythroderma requires immediate same-day specialist assessment, while suspected psoriatic arthritis requires rheumatology referral as soon as it is recognised.
- Ask about smoking, alcohol, weight, cardiovascular risk, mood and treatment practicality without implying blame; agree goals that matter to the person.
Key red flags
Diffuse tender erythema, sterile-looking pustules, fever, malaise, shivering, oedema, dehydration or altered observations require same-day specialist care.
A hot swollen joint, dactylitis, inflammatory back pain or painful enthesitis suggests psoriatic arthritis and needs prompt rheumatology assessment.
Rapid change after starting or stopping a medicine, especially systemic corticosteroid withdrawal, requires a full medication timeline and urgent advice if disease is unstable.
Major mood disturbance, hopelessness or self-harm thoughts are clinical severity markers and require direct risk assessment and appropriate urgent mental-health support.
Morning stiffness, swollen joints, whole-digit swelling, heel pain or inflammatory back pain can precede or follow cutaneous disease. A negative PEST does not exclude axial arthritis or inflammatory back pain.
Fever, malaise, widespread pustulation, rapidly spreading erythema, oedema, shivering or reduced urine output are not routine plaque symptoms. Check observations and arrange same-day specialist assessment.
Investigation priorities
Establish plaque, guttate or flexural phenotype and detect scalp, nail, palmoplantar or genital involvement.
Management branches
Adult plaque psoriasis amenable to topical treatment and without unstable features.
- Agree a formulation the person can use, demonstrate fingertip-unit quantities, and use emollient or soap substitute to soften scale while explaining fabric fire risk.
- Use a potent topical corticosteroid once daily plus a vitamin-D analogue once daily, applied separately morning and evening, for up to four weeks as NICE initial trunk-and-limb treatment.
- Review response, adherence, quantity, irritation and steroid adverse effects by four weeks; do not automatically continue potent steroid beyond the planned course.
- If goals are unmet, follow the NICE topical sequence or refer when extent, difficult site, distress or repeated failure makes topical-only care inadequate.