Types of psoriasis: the 5 main types and how they differ

This guide explains each main type in plain words, so you can describe what you see to a doctor. It can't tell you which type you have — only a doctor can do that, and a doctor can tell you if more than one applies.

Lists differ a little between organizations. The National Psoriasis Foundation (NPF) and NIAMS, part of the US National Institutes of Health, name five types. The American Academy of Dermatology (AAD) also describes nail psoriasis. The scalp is a place on the body rather than a separate type here.

Plaque psoriasis

This is the type most people mean when they say "psoriasis". The NPF says 80 to 90 percent of people with psoriasis have it.

• Look: raised, red patches covered with silvery-white scale. The AAD says they may itch.
• Skin of color: the NPF says plaques can look darker and thicker, and may be purple, gray or dark brown.
• Where: the AAD lists the scalp, elbows, knees and lower back, but it can appear anywhere.

More in Plaque psoriasis.

Guttate psoriasis

"Guttate" means drop-shaped. The AAD describes small, scaly, salmon-to-pink bumps that appear quite suddenly, mainly on the torso, arms and legs.

It often affects children and young adults, often after an infection such as strep throat. The AAD says it may clear in weeks or months, but it can come back or be followed by plaque psoriasis. The NPF says about 8 in 100 people with psoriasis have this type.

More in Guttate psoriasis.

Inverse psoriasis

Inverse psoriasis (so called because it appears in the body's folds, not on the outer surfaces) forms where skin touches skin. The AAD lists the armpits, genitals and the crease of the buttocks. NIAMS adds under the breasts and the groin.

It looks different from plaque psoriasis: patches are smooth, red and raw-looking with little scale. The AAD says they can be sore or painful. NIAMS says rubbing and sweating can make it worse.

Pustular psoriasis

Pustular psoriasis ("pustular" means pus-filled bumps) causes pus-filled bumps on red, swollen skin. The AAD says the bumps are not an infection.

There are two broad forms:

• Limited to the hands and feet. This is the usual pattern, according to the AAD and NIAMS. The AAD says the skin can be very sore or painful.
• Widespread. Most of the skin turns red and tender, then fills with pus-filled bumps. The AAD says the person often feels very sick, with fever, headache or muscle weakness, and calls it serious and life-threatening.

Erythrodermic psoriasis

"Erythrodermic" means widespread redness. NIAMS calls this type rare. The AAD describes skin over most of the body that looks burned, sometimes with chills, fever, weak muscles, a fast pulse and severe itch. It says this needs immediate medical care.

NIAMS says a severe sunburn or certain medicines can set it off. Don't stop or change a medicine because of this — talk to your doctor first.

Nail psoriasis

Psoriasis can affect fingernails and toenails. The AAD lists tiny dents (pits), white, yellow or brown color changes, crumbling or rough nails, and nails lifting away from the nail bed. Show nail changes to a doctor, who can tell whether psoriasis is the cause.

Psoriasis on the scalp and other places

Where psoriasis appears is not the same as its type. The NPF says around half of people with psoriasis have it on the scalp or face, and up to two-thirds have genital involvement. The AAD notes guttate spots can also appear on the face, scalp and ears. See Scalp psoriasis.

Can the type change?

Sometimes. The AAD says guttate psoriasis may clear and plaque psoriasis appear later, and the NPF says guttate can come back too. If your skin looks different from before, tell your doctor.

How to track your type in a diary

Notes make it easier for a doctor to see which type you have and whether it changes. You could record:

• where on the body the patches are, and whether in skin folds, hands, feet or nails
• how they look: raised patches, small spots, smooth red skin, pus-filled bumps
• itch, soreness or pain from 0 to 10
• anything new before it started, such as an infection, sunburn or a new medicine
• a photo of the same area once a week, in the same light

Example entry: Smooth red patch under my left breast, sore when I sweat, no real scale. Pain 3/10. Different from the dry patches on my elbows. Photo taken.

A diary app such as Velvi can keep these notes and photos in one place.

Questions to ask your doctor

• Which type of psoriasis do I have, and could it be something else?
• Do I have more than one type?
• Is this type likely to change over time?
• Which signs mean I should come back sooner?
• Does my type affect which treatments are suitable?
• Should my nails or joints be checked?