Psoriasis
Psoriasis — a chronic autoimmune condition in which skin cells multiply far faster than normal, building up into thick, scaly plaques. These patches are often silvery-white over red or discolored skin and commonly appear on the elbows, knees, scalp, and lower back.
Key points
- It is driven by an overactive immune system that accelerates the skin cell life cycle from weeks to just a few days.
- Plaque psoriasis is the most common type, though guttate, inverse, pustular, and erythrodermic forms also exist.
- Flares can be triggered by stress, infections, skin injury, cold weather, and certain medications.
- Gentle moisturizing supports comfort, but medical treatment is often needed to manage the underlying immune activity.
Psoriasis and the conditions it is mistaken for
| Often confused with | How to tell them apart |
|---|---|
| Atopic eczema | Blurred edges and dominant itch; psoriasis is sharply demarcated with silvery scale |
| Seborrhoeic dermatitis | Greasy yellowish scale in brows and nasolabial folds, not thick silvery scale on extensors |
| Tinea corporis | An advancing ring with a clearing centre; scrapings confirm fungus, and antifungals settle it |
| Lichen planus | Flat-topped violaceous papules with fine white lines, typically on wrists and ankles |
| Dandruff | Scalp psoriasis is thicker, sharply bordered and often crosses the hairline |
| Fungal nail infection | Pitting and onycholysis, usually alongside plaques elsewhere |
Why the plaques are thick and sharply edged
Psoriasis begins in the immune system. T cells activated in the skin signal along the interleukin-17 and interleukin-23 pathways, and keratinocytes respond by dividing far faster than they should: a trip from basal layer to shed cell that normally takes about a month is compressed into days. Cells reach the surface immature and pile up instead of shedding evenly — the silvery, laminated scale, and not a dryness problem.
The plaque is sharply demarcated because it marks a discrete patch of immune activity, not spreading irritant. Dilated dermal capillaries beneath it give the red or violet base and the pinpoint bleeding if scale is lifted. Typical sites follow suit: elbows, knees and other extensor surfaces, the scalp, the sacrum, the navel. Injury can seed a new plaque, and nails often show pitting or lifting from the bed.
What management realistically achieves
Softening scale comes first: nothing penetrates a thick crust. Emollients and keratolytics such as salicylic acid or urea reduce that layer over one to two weeks. Coal tar and medicated shampoos help the scalp. Natural light often improves plaques, though burning provokes them; less smoking and alcohol is associated with better control.
Beyond that, treatment is clinician-managed. Vitamin D analogues and topical corticosteroids are prescribed for localised plaques and judged at 4–8 weeks; phototherapy runs as a supervised course; systemic and biologic therapies target the immune pathways themselves — tumour necrosis factor alpha, interleukin-17, interleukin-23 — and need monitoring. None is a cure. Long clear periods are realistic, but psoriasis is managed rather than resolved, and relapse is expected rather than failure.
Signs that warrant a medical review
Joint symptoms matter most. Pain, morning stiffness lasting over half an hour, a swollen finger or toe, or heel pain alongside psoriasis can indicate psoriatic arthritis, which affects a substantial minority and causes permanent joint damage if untreated. It also carries higher rates of cardiovascular disease, hypertension, type 2 diabetes, metabolic syndrome, depression and anxiety, so blood pressure, lipids, glucose and mood are worth checking.
Two presentations need emergency assessment: redness spreading across most of the body with shivering or feeling unwell, and a sudden crop of sterile pustules with fever. Otherwise book an appointment if plaques involve the scalp, face, genitals or nails, cover more than a small area, have not shifted after a proper 4–8 week course, or affect sleep, work or mood.
Frequently asked
Is psoriasis just very dry skin?
No, psoriasis is an immune-driven condition that speeds up skin cell turnover, which is different from ordinary dryness even though the plaques can look and feel dry.
Can skincare help manage psoriasis?
Regular moisturizing and gentle, fragrance-free products can ease scaling and discomfort, but they complement rather than replace treatments prescribed by a healthcare professional.
Is psoriasis contagious?
No. It is generated by a person's own immune signalling and cannot pass between people through touch, towels or pools. Family clustering reflects inherited susceptibility, not transmission.
Can psoriasis be cured?
No treatment removes the underlying tendency, so psoriasis is described as managed rather than cured. Long periods of clear or near-clear skin are realistic; flares returning afterwards are part of the pattern.
What makes psoriasis flare?
Commonly reported triggers include stress, streptococcal throat infection, skin injury such as sunburn, cold dry weather, smoking, alcohol and certain prescribed medicines. Triggers vary, so a diary is often more informative than a general list.
Should I pick the scale off?
Better not to. Lifting scale exposes dilated capillaries and causes pinpoint bleeding, and injuring skin can seed a fresh plaque there. Softening it with an emollient or keratolytic is slower but less provoking.
Related topics
This is a foundational entry in the SYNC Skin Encyclopedia and is expanded over time. Educational information only — not medical advice.
