Psoriasis — what it is, how we treat it, and why it matters beyond the skin

About this guide

Psoriasis is one of the most under-treated conditions we see in primary care. Patients often arrive having been told it’s “just dry skin,” or having tried various moisturisers and steroid creams from previous prescriptions without a structured plan. The reality is that psoriasis is a chronic immune-mediated condition — closer in nature to eczema or asthma than to a passing rash — and it is highly treatable with the right combination of consistent daily care, the right topical or systemic treatment, and attention to the things that go with it (joints, mood, cardiovascular risk).

This guide covers:

• What psoriasis actually is — and why “you just need to moisturise” is incomplete
• The patterns it takes — chronic plaque, scalp, flexural, guttate, nail, and the rarer severe variants
• Beyond the skin — psoriatic arthritis, mood, and the metabolic conditions psoriasis tracks with
• Triggers — stress, infections, alcohol, smoking, and certain medications
• Topical treatments — what we use first, why combination matters, and how to approach scalp specifically
• When topicals aren’t enough — phototherapy, methotrexate, ciclosporin, and the modern biologics — and why these are referred out of primary care
• Things that may not help
• When to come and see us

It sits alongside our eczema series — the daily-care discipline (gentle cleansers, regular emollient, avoiding irritants) is shared between the two conditions, even though the specific treatments differ.

What psoriasis actually is

Psoriasis is an immune-mediated, inflammatory disease. The immune system over-reacts to a skin signal that isn’t really there, driving accelerated turnover of skin cells and chronic inflammation in the affected areas. The result — visible on the skin — is the characteristic thickened, red, scaly plaques, but the underlying disease process is happening at a deeper, immune level.

A few points worth understanding plainly:

• Psoriasis is not infectious or contagious. You cannot give it to your family, your partner, or anyone you swim with.
• Psoriasis is not caused by dirty skin. The plaques are a downstream consequence of immune activity, not surface contamination.
• Psoriasis is genetic in part — about 30% of patients have a family history. The “starter switch” is genetic; the “flare switch” is usually a trigger (see below).
• Psoriasis is a lifelong condition in the great majority of patients. Like eczema, asthma, or hypertension, the goal is good control most of the time, not “cure.”
• Psoriasis is highly treatable. Most patients with mild-to-moderate disease do well with topical therapy. Patients with more severe disease have access to genuinely effective systemic and biologic treatments (referred out of primary care).

In Asian skin, psoriasis can look slightly different from the textbook bright-red Western images — plaques may appear deeper red, violet, or brown, and after they settle, post-inflammatory hyperpigmentation (PIH) is common and can persist for months. Treating early reduces the pigmentary aftermath. (See our acne guide for a fuller discussion of PIH in Asian skin — the same principles apply.)

The patterns it takes

Chronic plaque psoriasis (the most common — about 80% of cases)

Well-defined, raised, red plaques covered with silvery-white scale. Most commonly on:

• Elbows (extensor surfaces)
• Knees (extensor surfaces)
• Lower back / sacrum
• Scalp (often the first or only site)
• Less commonly the trunk, arms, and legs

Plaques can be itchy, sore, or simply visible without much sensation. They tend to be bilateral and symmetric, which helps distinguish from eczema (often asymmetric, flexural).

Scalp psoriasis

Often the first site of presentation, and the one patients find most distressing because it’s visible. Tends to extend slightly beyond the hairline at the back of the neck and along the front. Usually does not cause hair loss unless very severe and chronic — the inflammation slows hair growth temporarily but is reversible with treatment.

Inverse (flexural) psoriasis

Affects the body folds — under the breasts, in the groin, between the buttocks, in the armpits. Looks different from plaque psoriasis: less scale, more shiny redness, often misdiagnosed as fungal infection or intertrigo. Common in patients who also have plaque psoriasis elsewhere; sometimes the only pattern.

Guttate psoriasis

Sudden onset of multiple small (1–10 mm), drop-shaped pink plaques scattered across the trunk, arms, and legs — often after a streptococcal sore throat in younger patients. May resolve spontaneously over months, or evolve into chronic plaque psoriasis. Treatment is usually topical with attention to the underlying infection if recent.

Nail psoriasis

Affects 20–50% of patients with skin psoriasis, and a smaller proportion of patients with no skin involvement at all. Features include:

• Pitting — small surface dents in the nail plate
• Onycholysis — separation of the nail from the underlying nail bed (often with a yellow-brown “oil drop” sign)
• Subungual hyperkeratosis — thickened material under the nail
• Trachyonychia — rough, sandpapered surface
• Splinter haemorrhages

Nail psoriasis is also a marker for psoriatic arthritis (see below) and is one of the things we ask about specifically at every visit.

Rare and severe variants — refer urgently

These are uncommon but matter when they happen:

• Pustular psoriasis — sterile pustules on red, inflamed skin; can be localised (palms/soles) or generalised (rare, can be life-threatening). Generalised pustular psoriasis with fever and feeling unwell is a hospital problem.
• Erythrodermic psoriasis — generalised redness covering most of the body, with shedding of large amounts of skin. Risk of fluid loss, temperature dysregulation, and infection. Hospital-level care.

If your skin looks dramatically more inflamed than usual, you have widespread pustules, or you feel unwell, please contact us same day or attend the nearest emergency department.

Beyond the skin — what psoriasis tracks with

Psoriasis is more than a skin condition. The same immune dysregulation that produces the plaques is associated with several conditions worth screening for and managing.

Psoriatic arthritis (PsA)

Affects up to 30% of patients with psoriasis at some point. Signs to watch for:

• Joint pain, stiffness, or swelling — typically asymmetric, often involving the small joints of the hands and feet (including the joint nearest the nail), knees, ankles, and lower back / sacroiliac joints
• Stiffness lasting more than 30 minutes after waking — different in pattern from osteoarthritis (which improves quickly with movement)
• Dactylitis — “sausage finger” or “sausage toe” — diffuse swelling of an entire digit
• Enthesitis — pain at the points where tendons attach to bone (heel, elbow, base of spine)
• Nail changes (see above) — strong association with PsA

Psoriatic arthritis can be destructive if untreated — joint damage in the first few years sets the trajectory for life. At every visit we will ask about joint symptoms and nail changes because catching PsA early changes outcomes. If we suspect it, we refer to a rheumatologist for confirmation and treatment.

Cardiovascular and metabolic conditions

Psoriasis travels with:

• Cardiovascular disease — increased risk of heart attack and stroke, even after adjusting for traditional risk factors
• Type 2 diabetes and metabolic syndrome
• Obesity — bidirectional; weight reduction can meaningfully improve psoriasis
• Metabolic-associated fatty liver disease (MASLD)
• Inflammatory bowel disease — Crohn’s disease in particular shares immune pathways

This isn’t a coincidence — chronic systemic inflammation is the shared driver. Treating psoriasis well is part of the broader cardiovascular picture; see our cardiovascular-kidney-metabolic (CKM) guide for how these conditions link together.

Mental health

Depression and anxiety are more common in people with psoriasis than in the general population. This isn’t only about appearance — chronic systemic inflammation appears to play a role in mood. We ask, and we treat. If your psoriasis is affecting your mood, school, work, or relationships, please tell us.

Triggers — what makes flares more likely

Psoriasis has a baseline activity, and then flares triggered by:

• Stress — both acute and chronic. One of the most consistent triggers patients report.
• Infections — particularly streptococcal sore throat (classically before guttate psoriasis), but also viral infections and chest infections
• Skin injury (the Koebner phenomenon) — psoriasis can appear on previously normal skin at sites of trauma — scratches, burns, insect bites, surgical scars, even friction from belts or backpacks
• Smoking — more severe disease, less responsive to treatment, more cardiovascular risk
• Alcohol — more severe disease and interacts with several psoriasis medications
• Certain medications — lithium, beta-blockers, antimalarials (chloroquine, hydroxychloroquine), some NSAIDs, and rapid withdrawal of oral or systemic corticosteroids (which can cause severe rebound or pustular flare — one of the reasons we are cautious with oral steroids in psoriasis)
• Cold, dry weather — many patients improve in warmer, sunnier conditions; some worsen with humidity. Local Singapore weather is generally favourable to psoriasis compared to colder climates.
• Sunlight — controlled sun exposure helps many patients (the basis for medical phototherapy). Sunburn can trigger a flare via Koebner — sensible exposure, not extremes, is the rule.

Daily skincare — the foundation that everything else builds on

The discipline is similar to the eczema everyday skincare approach:

• Moisturise generously, twice a day, every day — including over plaques. Emollients reduce scale, reduce itch, and make topical treatments penetrate better. Ceramide-containing or oil-based formulations work well.
• Lukewarm, short showers — hot water strips and irritates.
• Pat dry, then apply moisturiser within minutes while skin is still slightly damp (“soak and seal”).
• Fragrance-free, non-soap cleansers — see the eczema everyday skincare guide for specific local products.
• Avoid scrubbing or picking at plaques — scratching off scale can trigger Koebner and worsen the condition.
• Sensible sun exposure in moderation often helps; sunscreen on un-affected skin to prevent sunburn (which can trigger Koebner).

These don’t treat psoriasis on their own, but every active treatment we add works better on a well-moisturised baseline.

Topical treatments — what we use first

Most patients with mild-to-moderate plaque psoriasis respond well to topical therapy. We typically build the regimen in stages.

Topical corticosteroid — the workhorse

The first-line anti-inflammatory treatment. Choice of potency depends on the site and severity of the plaque:

Apply once or twice daily to active plaques. Continue for 2–4 weeks, then assess. Step down to weaker agent or maintenance regimen as plaques settle.

We are careful with face, flexures, and prolonged use of potent steroids to avoid skin thinning and steroid rebound. If a site needs ongoing treatment, we usually combine with a non-steroid agent (vitamin D analogue, see below) or step down to a weaker steroid for maintenance.

Vitamin D analogue — calcipotriol

Calcipotriol (Daivonex) is a topical vitamin D3 analogue that normalises the over-active skin-cell turnover that drives psoriasis. It is steroid-sparing, well-tolerated, and effective — particularly for chronic plaque psoriasis.

Two practical notes:

• We don’t routinely stock calcipotriol or related derm specialty products in our dispensary because demand is intermittent. We order it via online pharmacy when it’s prescribed, with a typical delivery time of 1–3 working days. This is a normal workflow at our clinic for less-frequently-used medications — please ask if you’d like more information.
• Apply twice daily to plaques. Avoid the face and flexures (irritation). Avoid using more than ~100 g per week (the dose at which systemic absorption can affect calcium levels — practically rare at typical use).

Combination — calcipotriol + betamethasone (Daivobet, Dovobet)

A combination product that pairs the vitamin D analogue with a potent steroid in one tube. Often more effective than either agent alone, with better cosmetic acceptance (one application instead of two), and we use it commonly as we step up treatment.

Same ordering note as for calcipotriol on its own — typically obtained via online pharmacy.

Coal tar

Older but still useful. Reduces inflammation and scale. Available as:

• Coal tar shampoo (Tarmed, T/Gel, Sebitar) — well-tolerated for scalp psoriasis
• Coal tar bath additive — for widespread body involvement
• Coal tar cream / ointment — less commonly used now (smell, staining)

Coal tar can stain clothes and bedding; it has a distinctive smell that some patients dislike. For others — particularly with persistent scalp involvement — it’s a useful adjunct.

Salicylic acid

A keratolytic — softens and lifts thick scale to allow other treatments to penetrate. Often added to a steroid or vitamin D analogue (combination products available). Useful particularly on thick scalp plaques or stubborn extensor-surface plaques.

Topical calcineurin inhibitors (tacrolimus, pimecrolimus)

Non-steroidal anti-inflammatory creams useful for face, eyelids, flexures, and genital psoriasis where steroids are difficult to use long-term. Off-label for psoriasis but well-tolerated in these specific sites.

Scalp psoriasis — practical approach

Often the most distressing site for patients, and often the one most under-treated. A workable routine:

1. Soften the scale first — a coal tar shampoo or salicylic acid–containing shampoo (Tarmed, Capasal), used 2–3 times a week, lifts scale and lets active treatment penetrate.
2. Active treatment — a potent topical corticosteroid in scalp solution / lotion form (e.g. Diprosalic scalp lotion = betamethasone + salicylic acid), applied to the affected scalp once daily for 2–4 weeks initially. Massage gently; leave overnight where tolerated.
3. Step down to maintenance — once controlled, reduce frequency. Daivobet scalp gel (calcipotriol + betamethasone) is a useful step-down or maintenance option if available.
4. Comb through gently in the shower to lift loose scale; never scrape with a hard implement.
5. Avoid harsh shampoos during active treatment.

Hair is usually preserved. Scalp psoriasis does not generally cause permanent hair loss, but inflammation can slow hair growth temporarily. See our alopecia guide for more on hair loss specifically if relevant.

When topicals aren’t enough — what comes next

If topical therapy doesn’t control psoriasis adequately, or the disease is moderate-to-severe at presentation (large body surface area, joint involvement, significant impact on life), we refer to dermatology — either at the National Skin Centre (NSC) or to a private dermatologist. The next-step treatments require specialist supervision.

The main options:

Phototherapy (Narrowband UVB — NB-UVB)

Controlled, narrow-wavelength UVB delivered in a specialist setting (cabin or hand-held), typically 2–3 times a week for 8–12 weeks. Highly effective for moderate plaque psoriasis without the side effects of systemic medication. Available at NSC and at some private dermatology clinics.

Systemic medication — oral

Reserved for moderate-to-severe disease unresponsive to phototherapy, or where phototherapy is impractical:

• Methotrexate — once-weekly oral or subcutaneous; needs regular blood monitoring (FBC, liver function); avoided in pregnancy and planning
• Ciclosporin — for short bursts of severe disease; needs blood pressure and kidney monitoring
• Acitretin (oral retinoid) — particularly useful for pustular and palmoplantar psoriasis; avoid in pregnancy and for 3 years afterwards
• Apremilast (oral PDE4 inhibitor) — newer; well-tolerated; modest efficacy

Biologics — modern targeted therapy

A class of injectable medications that target specific immune pathways involved in psoriasis. Highly effective — many patients achieve near-complete clearance. The main classes used in Singapore:

• Anti-TNF — adalimumab (Humira), etanercept (Enbrel), infliximab (Remicade)
• Anti-IL-17 — secukinumab (Cosentyx), ixekizumab (Taltz)
• Anti-IL-23 — guselkumab (Tremfya), risankizumab (Skyrizi), ustekinumab (Stelara — also targets IL-12)

These are specialist-led, expensive, and require ongoing monitoring (infection screening, TB screening, hepatitis screening). They have transformed outcomes for moderate-to-severe psoriasis over the past 15 years. Coverage by insurance and integrated shield plans varies — your dermatologist will discuss financial implications alongside clinical fit.

We are happy to discuss the referral process and what to expect at your specialist visit. We will also continue to manage your overall health — cardiovascular risk factors, mood, weight, joint symptoms — alongside the dermatology team.

Things that may not help

A few areas where popular advice and clinical evidence diverge:

• “Psoriasis-cure” diets sold online — gluten-free, dairy-free, paleo, anti-inflammatory diets — there is no good evidence that any specific diet cures psoriasis. A healthy, weight-managing dietary pattern (Mediterranean-style, plant-forward, limited ultra-processed food) does help broader inflammation and supports weight reduction, which in turn improves psoriasis. See our medical weight management guide.
• Probiotic supplements — limited evidence for psoriasis specifically.
• Topical “natural” remedies — coconut oil, tea tree oil, aloe vera — emollient effect is fine; they don’t replace active treatment.
• “Detoxes” — no evidence for any specific psoriasis benefit; some carry risk.
• Aggressive scrubbing of plaques — can trigger Koebner and worsen the condition.
• Stopping a topical steroid abruptly after long use — can cause rebound flare. Step-down with our guidance rather than stopping suddenly.
• Oral corticosteroids for psoriasis flares — generally not used routinely because of the rebound flare risk on withdrawal, sometimes severe (pustular).
• Indefinite “wait and see” — without active treatment, plaques persist, and PsA risk goes unrecognised.

If you’ve tried something specific and it has helped, please tell us — we’d rather know than have you stop mentioning it.

When to come and see us

Worth a clinic visit if:

• You have plaques you suspect are psoriasis — the first step is confirming the diagnosis and starting structured treatment
• You have been using over-the-counter products without much improvement
• You have any joint symptoms — pain, stiffness, swelling, particularly in hands, feet, or back
• You have nail changes — pitting, separation, thickening — particularly with skin involvement
• Your psoriasis is widespread, affecting your scalp visibly, or in flexural / genital areas — these need specific approaches
• Your psoriasis is affecting your mood, work, school, or social life — this matters and deserves treatment
• Topical treatment isn’t controlling your psoriasis — we’ll review the regimen, optimise it, and refer to dermatology if escalation is needed
• You have psoriasis and another medical condition we should be screening for (cardiovascular risk, diabetes, fatty liver, inflammatory bowel disease, depression)

Urgent — same-day attention or A&E

• Widespread sudden redness covering most of your skin with shedding (erythrodermic psoriasis)
• Widespread pustules with fever or feeling unwell (generalised pustular psoriasis)
• Rapidly worsening joint swelling, severe joint pain, or inability to use a joint — possible severe psoriatic arthritis flare needing urgent review

Get in touch

Joo Chiat — 172 Joo Chiat Road, #01-01, Singapore 427443 · Tel 6920 1952

Punggol — 658 Punggol East, #01-04, Singapore 820658 · Tel 6312 4589

Email — admin@ktmc.sg

References

Guidelines and consensus statements

• Menter A, Strober BE, Kaplan DH, et al. Joint AAD-NPF guidelines of care for the management and treatment of psoriasis with biologics. American Academy of Dermatology / National Psoriasis Foundation. J Am Acad Dermatol. 2019;80(4):1029–1072.
• Elmets CA, Korman NJ, Prater EF, et al. Joint AAD-NPF guidelines of care for the management and treatment of psoriasis with topical therapy and alternative medicine modalities for psoriasis severity measures. J Am Acad Dermatol. 2021;84(2):432–470.
• Smith CH, Yiu ZZN, Bale T, et al. British Association of Dermatologists guidelines for biologic therapy for psoriasis 2020 — a rapid update. Br J Dermatol. 2020;183(4):628–637.
• Nast A, Smith C, Spuls PI, et al. EuroGuiDerm Guideline on the systemic treatment of Psoriasis vulgaris. J Eur Acad Dermatol Venereol. 2020;34(11):2461–2498.

Psoriatic arthritis

• Coates LC, Kavanaugh A, Mease PJ, et al. Group for Research and Assessment of Psoriasis and Psoriatic Arthritis 2015 treatment recommendations for psoriatic arthritis. Arthritis Rheumatol. 2016;68(5):1060–1071.
• Singh JA, Guyatt G, Ogdie A, et al. 2018 American College of Rheumatology/National Psoriasis Foundation guideline for the treatment of psoriatic arthritis. Arthritis Rheumatol. 2019;71(1):5–32.

Comorbidities

• Mehta NN, Yu Y, Pinnelas R, et al. Attributable risk estimate of severe psoriasis on major cardiovascular events. Am J Med. 2011;124(8):775.e1–775.e6.
• Daudén E, Castañeda S, Suárez C, et al. Clinical practice guideline for an integrated approach to comorbidity in patients with psoriasis. J Eur Acad Dermatol Venereol. 2013;27(11):1387–1404.

This information is for general education only and is not a substitute for medical advice. Psoriasis treatment is individualised — please attend a consultation for assessment. v1.0 · April 2026 · Review due April 2028.