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

In brief

• Psoriasis is a long-term immune condition that causes thick, red, scaly plaques, and it is not infectious.
• Most mild-to-moderate psoriasis responds to topical treatment, such as a steroid or calcipotriol, plus daily moisturising.
• Up to 30% of people with psoriasis develop psoriatic arthritis, and psoriasis is linked with heart disease, diabetes and low mood, so we check for these.
• More severe psoriasis is referred to a dermatologist for phototherapy, tablets or biologics.
• Seek same-day care for redness over most of the skin, widespread pustules with fever, or rapidly worsening joint swelling.

We diagnose and manage psoriasis at our Punggol clinic. Book a skin appointment.

What psoriasis actually is

Psoriasis is a chronic, immune-mediated inflammatory disease, closer to eczema or asthma than to a passing rash. The immune system over-reacts to a skin signal that isn’t really there, speeding up skin-cell turnover and causing chronic inflammation. The thickened, red, scaly plaques are the visible result of a deeper immune process.

• It is not infectious. You can’t pass it to your family, your partner or anyone you swim with.
• It is not caused by dirty skin. Plaques come from immune activity.
• It is partly genetic. About 30% of patients have a family history. Genes set the “starter switch”; a trigger usually flips the “flare switch”.
• It is lifelong for the great majority. As with asthma or hypertension, the goal is good control most of the time, not cure.
• It is highly treatable. Most mild-to-moderate disease does well on topical treatment. More severe disease has effective systemic and biologic treatments, for which we refer.

In Asian skin, plaques may look deeper red, violet or brown rather than textbook bright red. After they settle, post-inflammatory hyperpigmentation (PIH) is common and can last months. Treating early reduces these marks; our acne guide covers PIH in more detail.

The patterns it takes

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

Well-defined, raised, red plaques with silvery-white scale. They are most common on the elbows and knees (extensor surfaces), lower back / sacrum and scalp (often the first or only site), and less common on the trunk, arms and legs.

Plaques may itch, hurt or just show. They tend to be bilateral and symmetrical, which helps tell them from eczema (often asymmetric and in skin folds).

Scalp psoriasis

The most distressing site, because it shows. It often extends just past the hairline at the back of the neck and the front. It usually does not cause hair loss unless very severe and chronic. Inflammation can slow hair growth for a while, but this reverses with treatment.

Inverse (flexural) psoriasis

Affects the body folds: under the breasts, the groin, between the buttocks and the armpits. It has less scale and more shiny redness than plaque psoriasis, and is often misdiagnosed as fungal infection or intertrigo. It often accompanies plaque psoriasis elsewhere, but is sometimes the only pattern.

Guttate psoriasis

A sudden crop of many small (1–10 mm), drop-shaped pink plaques on the trunk, arms and legs, often after a streptococcal sore throat in younger people. It may clear by itself over months, or develop into chronic plaque psoriasis. Treatment is usually topical, plus attention to any recent infection.

Nail psoriasis

Affects 20–50% of people with skin psoriasis, and some with no skin involvement. Features:

• Pitting: small dents in the nail surface
• Onycholysis: the nail separating from the nail bed, often with a yellow-brown “oil drop” sign
• Subungual hyperkeratosis: thickened material under the nail
• Trachyonychia: a rough, sandpaper-like surface
• Splinter haemorrhages

Nail psoriasis is also a marker for psoriatic arthritis (below).

Rare and severe variants — refer urgently

• Pustular psoriasis: sterile pustules on red, inflamed skin, either localised (palms and soles) or generalised (rare, and can be life-threatening). Generalised pustular psoriasis with fever and feeling unwell is a hospital problem.
• Erythrodermic psoriasis: redness over most of the body, with heavy shedding of skin. It risks fluid loss, temperature dysregulation and infection, and needs hospital-level care.

If your skin suddenly becomes much more inflamed, you develop widespread pustules, or you feel unwell, contact us the same day or go to the nearest emergency department.

Beyond the skin — what psoriasis tracks with

Psoriatic arthritis (PsA)

Affects up to 30% of people with psoriasis at some point. Watch for:

• Joint pain, stiffness or swelling, typically asymmetric. It often involves 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. Osteoarthritis, by contrast, eases quickly with movement.
• Dactylitis: a “sausage finger” or “sausage toe”, with the whole digit swollen.
• Enthesitis: pain where tendons attach to bone (heel, elbow, base of the spine).
• Nail changes, which are strongly linked with PsA.

Untreated PsA can be destructive: joint damage in the first few years sets the course for life. We ask about joint symptoms and nail changes at every visit, because catching PsA early changes outcomes. If we suspect PsA, we refer you to a rheumatologist to confirm and treat it.

Cardiovascular and metabolic conditions

Psoriasis is linked with:

• Cardiovascular disease: a higher risk of heart attack and stroke, even after adjusting for traditional risk factors
• Type 2 diabetes and metabolic syndrome
• Obesity: the link runs both ways, and weight reduction can meaningfully improve psoriasis
• Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly called non-alcoholic fatty liver disease (NAFLD)
• Inflammatory bowel disease, particularly Crohn’s disease, which shares immune pathways

Chronic systemic inflammation is the shared driver, so treating psoriasis well is part of cardiovascular care. See our cardiovascular-kidney-metabolic (CKM) guide for how these conditions link.

Mental health

Depression and anxiety are more common with psoriasis, and not only because of appearance; chronic inflammation appears to affect mood. We ask, and we treat. Tell us if psoriasis is affecting your mood, school, work or relationships.

Triggers — what makes flares more likely

Flare triggers include:

• Stress, acute or chronic: one of the most consistent triggers.
• Infections, particularly streptococcal sore throat (classically before guttate psoriasis), but also viral and chest infections.
• Skin injury (the Koebner phenomenon). Psoriasis can appear on normal skin at sites of trauma: scratches, burns, insect bites, surgical scars, even friction from belts or backpacks.
• Smoking: more severe disease, poorer response to treatment and more cardiovascular risk.
• Alcohol: more severe disease, and interactions with several psoriasis medicines.
• Certain medications: lithium, beta-blockers, antimalarials (chloroquine, hydroxychloroquine), some NSAIDs, and rapid withdrawal of oral or systemic corticosteroids. Steroid withdrawal can cause a severe rebound or pustular flare, one reason we are cautious with oral steroids in psoriasis.
• Cold, dry weather. Many people improve in warmer, sunnier conditions, though some worsen with humidity. Singapore’s weather is generally favourable compared with colder climates.
• Sunlight. Controlled sun exposure helps many people (the basis for medical phototherapy). Sunburn can trigger a flare through the Koebner effect, so be sensible, not extreme.

Daily skincare — the foundation that everything else builds on

The approach is similar to our eczema everyday skincare guide:

• Moisturise generously, twice a day, every day, including over plaques. Emollients reduce scale and itch, and help treatments penetrate. Ceramide-containing or oil-based products work well.
• Short, lukewarm showers. Hot water strips and irritates.
• Pat dry, then moisturise within minutes while the skin is still slightly damp (“soak and seal”).
• Fragrance-free, non-soap cleansers, as listed in the eczema guide.
• Don’t scrub or pick at plaques. Removing scale can trigger the Koebner effect.
• Sensible sun exposure often helps. Use sunscreen on unaffected skin to prevent sunburn.

These don’t treat psoriasis, but every active treatment works better on well-moisturised skin.

Topical treatments — what we use first

Most mild-to-moderate plaque psoriasis responds well to topicals, built up in stages.

Topical corticosteroid — the workhorse

The first-line anti-inflammatory treatment, with potency matched to the site and severity:

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

We take care with the face, skin folds and prolonged use of potent steroids, to avoid skin thinning and steroid rebound. If a site needs ongoing treatment, we usually add a non-steroid agent (a vitamin D analogue, below) or switch 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 in psoriasis. It is steroid-sparing, well tolerated and effective, particularly for chronic plaque psoriasis.

• We order it through an online pharmacy when prescribed, usually delivered in 1–3 working days. We don’t routinely stock it or related specialty products, as demand is intermittent.
• Apply twice daily to plaques, avoiding the face and skin folds (irritation). Don’t use more than about 100 g a week, the dose at which absorption can affect calcium levels (rare at typical use).

Combination — calcipotriol + betamethasone (Daivobet, Dovobet)

The vitamin D analogue and a potent steroid in one tube. It is often more effective than either alone, needs one application instead of two, and is a common step up. It is also usually ordered through an online pharmacy.

Coal tar

Older but still useful for inflammation and scale. Forms include:

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

Coal tar can stain clothes and bedding, and some people dislike the smell. For persistent scalp psoriasis in particular, it is a useful add-on.

Salicylic acid

A keratolytic that softens and lifts thick scale so other treatments can penetrate. Often combined with a steroid or vitamin D analogue, it is useful on thick scalp plaques and stubborn extensor-surface plaques.

Topical calcineurin inhibitors (tacrolimus, pimecrolimus)

Non-steroid anti-inflammatory creams for the face, eyelids, skin folds and genital area, where long-term steroid use is difficult. Off-label for psoriasis, but well tolerated at these sites.

Scalp psoriasis — practical approach

It is often under-treated. A workable routine:

1. Soften the scale first with a coal tar or salicylic acid shampoo (Tarmed, Capasal), used 2–3 times a week, so active treatment can penetrate.
2. Apply a potent steroid in scalp solution or lotion form (for example Diprosalic scalp lotion: betamethasone + salicylic acid) once daily for 2–4 weeks at first. Massage in gently and leave overnight where tolerated.
3. Step down to maintenance once controlled, by using it less often. 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.

For hair loss more generally, see our alopecia guide.

When topicals aren’t enough — what comes next

If topicals don’t control psoriasis, or it is moderate-to-severe from the start (large body surface area, joint involvement, major impact on life), we refer to dermatology at the National Skin Centre (NSC) or a private dermatologist. The next-step treatments need specialist supervision.

Phototherapy (Narrowband UVB — NB-UVB)

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

Systemic medication — oral

For moderate-to-severe disease that doesn’t respond to phototherapy, or where it is impractical:

• Methotrexate: once weekly, oral or subcutaneous. Needs regular blood monitoring (FBC, liver function); avoided in pregnancy and when planning one.
• Ciclosporin: short bursts for severe disease, with blood pressure and kidney monitoring.
• Acitretin (an oral retinoid): particularly useful for pustular and palmoplantar psoriasis. Avoid in pregnancy and for 3 years afterwards.
• Apremilast (an oral PDE4 inhibitor): newer, well tolerated, modest efficacy.

Biologics — modern targeted therapy

Injectable medicines targeting specific immune pathways. They are highly effective, and many people 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, which also targets IL-12)

Biologics are specialist-led, expensive and need ongoing monitoring, including infection, TB and hepatitis screening. They have transformed outcomes for moderate-to-severe psoriasis over the past 15 years. Insurance and Integrated Shield plan coverage varies; your dermatologist will discuss costs.

We keep managing your overall health (cardiovascular risk factors, mood, weight, joint symptoms) alongside the dermatology team.

Things that may not help

• “Psoriasis-cure” diets sold online (gluten-free, dairy-free, paleo, anti-inflammatory): no good evidence that any diet cures psoriasis. A healthy eating pattern (Mediterranean-style, plant-forward, limited ultra-processed food) does help wider inflammation and weight loss, which in turn improves psoriasis. See our medical weight management guide.
• Probiotic supplements: limited evidence for psoriasis.
• Topical “natural” remedies (coconut oil, tea tree oil, aloe vera): fine as emollients, but no replacement for active treatment.
• “Detoxes”: no evidence of psoriasis benefit, and some carry risk.
• Scrubbing plaques: can worsen psoriasis through the Koebner effect.
• Stopping a topical steroid abruptly after long use: can cause a rebound flare; step down with our guidance.
• Oral corticosteroids for flares: generally not used routinely, because of the risk of a rebound flare on withdrawal, sometimes severe (pustular).
• Indefinite “wait and see”: without active treatment, plaques persist and PsA can go unrecognised.

If something has helped you, tell us. We would rather know.

When to come and see us

Book a visit if:

• You have plaques you suspect are psoriasis, so we can confirm the diagnosis and start structured treatment.
• Over-the-counter products haven’t helped much.
• You have any joint symptoms: pain, stiffness or swelling, particularly in the hands, feet or back.
• You have nail changes (pitting, separation, thickening), particularly with skin involvement.
• Your psoriasis is widespread, visible on your scalp, or in skin folds or the genital area. These need specific approaches.
• Psoriasis is affecting your mood, work, school or social life. This matters and deserves treatment.
• Topical treatment isn’t controlling it. We’ll optimise the regimen and refer to dermatology if needed.
• You have psoriasis and another condition we should screen for (cardiovascular risk, diabetes, fatty liver, inflammatory bowel disease, depression).

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 being unable to use a joint: possibly a severe psoriatic arthritis flare needing urgent review

Get in touch

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

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

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.
• Rinella ME, Lazarus JV, Ratziu V, et al. A multisociety Delphi consensus statement on new fatty liver disease nomenclature. J Hepatol. 2023;79(6):1542–1556.

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. v1.1 · October 2026 (v1.0 April 2026) · Review due April 2028.