Psoriasis is a lifelong immune disorder that causes rashes and other symptoms to develop on the skin. The rash can be itchy and painful.

The most common type, plaque psoriasis, starts out as small red or discolored bumps that grow larger and form a scale.

Scratching the rash can pull scales off the skin and cause bleeding. As the rash progresses, bumpy red and silvery-scaled patches can develop. However, on darker skin tones, psoriasis appears more as purple patches with gray scales.

Psoriasis can occur on the skin anywhere on the body. It most often develops on the knees, elbows, or scalp.

It is a systemic condition, which means it affects the body from the inside. It is not contagious, meaning that one person cannot pass psoriasis to another.

There are several different types of psoriasis with different symptoms. However, the symptoms and types often overlap.

Plaque psoriasis rash

This is the most common form. According to the American Academy of Dermatology (AAD), 80–90% of people with psoriasis have this form.

A plaque psoriasis rash consists of cracked and inflamed patches of plaque that have a coating of flaky scales.

It commonly appears on the scalp, lower back, elbows, and knees. The patches can be sore and itchy, and they can get thicker.

On lighter skin, the plaques may appear pink or red. On darker skin, the rash may appear darker than the surrounding skin. On all skin colors, the rash can cause a gray or silvery coating of scales.

Scalp psoriasis rash

With scalp psoriasis, plaques form on the scalp and possibly beyond the hairline, on the forehead, the back of the neck, and behind the ears.

A person may experience:

  • flakes forming that may look like dandruff
  • itchy and thickened skin
  • cracking of the skin
  • red or pink patches on lighter skin tone
  • gray or darker patches on darker skin tone
  • hair loss, in more severe cases

Anyone who has scalp psoriasis may need to see a doctor. Scalp psoriasis can lead to hair loss if symptoms become severe, and cracked and broken skin may cause infection. Medical help can help lower these risks.

Nail psoriasis rash

People with plaque or other types of psoriasis may develop nail psoriasis.

Fingernails and toenails may develop pits, and they may thicken, crumble, or fall off.

Some people develop nail psoriasis without having another type of psoriasis.

Pustular psoriasis rash

Pustular psoriasis gives rise to painful, pus-filled bumps. They usually affect the palms of the hands and the soles of the feet. The skin surrounding the bumps becomes swollen and red or discolored.

When the bumps dry, they leave behind brown, scaly spots.

A person may also experience fever, chills, weak muscles, little appetite, too much itching, and tiredness.

Inverse psoriasis rash

Inverse psoriasis leads to sore skin in areas where skin is in contact with skin, or skin folds.

These include:

  • armpits
  • behind the knees
  • groin
  • buttocks
  • genitals
  • under the breasts

On lighter skin, inverse psoriasis areas may appear pink or red. On darker skin, the patches may be gray or darker than the surrounding skin.

Guttate psoriasis rash

Guttate psoriasis often develops after an illness, such as strep throat. It affects around 8% of people with psoriasis, according to the National Psoriasis Foundation.

A person with guttate psoriasis will typically develop small red, pink, or discolored spots all over the body, most often on the chest, legs, and arms.

Erythrodermic psoriasis rash

Erythrodermic psoriasis is a rare and severe condition. Individuals who develop symptoms should seek medical treatment immediately, as it can sometimes become life threatening.

Symptoms include:

  • red or inflamed skin across a large area of the body, which looks like a burn
  • intense pain
  • itching
  • a rapid heartbeat
  • fluid loss, due to skin damage

A person may also feel very hot or very cold, as their body is not able to maintain a stable temperature.

People who have had a severe sunburn, take particular medications, or have another form of psoriasis that is untreated can develop erythrodermic psoriasis.

Find out more here about erythrodermic psoriasis.

Psoriasis affects individuals in different ways, and it can take multiple forms.

However, people with all types of psoriasis typically have at least one of the following symptoms:

  • itchy, sore, or burning patches on the skin
  • red or darker patches of skin, with silvery spots
  • small red or discolored spots on the skin
  • dry, cracked skin
  • changes in the nails
  • painful and swollen joints

Most forms of psoriasis typically go through phases. During a flare, symptoms may become more severe for a while, but then they may ease or go away for a time.

Psoriasis is a lifelong condition. However, people can usually manage it effectively with over-the-counter treatments and medication.

Other conditions that can cause a rash similar to psoriasis include:

  • Eczema: Eczema is a skin condition that causes itching and discomfort. However, the skin is typically thinner and less red than in psoriasis.
  • Shingles: This rash results from herpes zoster, the same virus that causes chicken pox. Shingles usually starts with a tingling on one side of the body. After this, itchy, painful blisters appear in that area. These form scabs 7–10 days after they appear. The rash usually disappears within 2–4 weeks.
  • Heat rash: This can cause itchy red blisters in skin folds. People sometimes confuse heat rash with psoriasis, but a physician can make an appropriate diagnosis with a simple examination.
  • Lichen planus: This can appear on the skin as reddish or discolored bumps anywhere on the skin, including the genitals and the scalp, or as white dots in the mouth. Find out more here.
  • Pityriasis rosea: This rash develops in patches. It starts with one large patch, usually on the trunk. After around 2 weeks, more patches develop, usually on the trunk, arms, or legs. The pattern may look like a fir tree. The skin feels scaly. On lighter skin, the color will be pinkish. On darker skin, it will be violet to dark gray. The rash usually disappears after 6–8 weeks. It is unclear what causes it.
  • Ringworm: A fungal infection forms a circle-shaped rash that is itchy and red. Find out more here.
  • Seborrheic dermatitis: It is an itchy, red skin condition usually found on the scalp and other oily areas of the body. Find out more here.

Various medical treatments are available that can often reduce mild symptoms effectively.

These include:

  • light therapy
  • oral medications
  • corticosteroids
  • topical treatments

Treatment will depend on the type of psoriasis, where the rash is, the severity, and how it affects the individual.

For some people, some guidelines suggest treating psoriasis with a type of drug known as a biologic. The decision will depend on the type of psoriasis and severity of symptoms.

Biologic drugs affect the way the immune system works. They can lower the number of flares and the severity of symptoms. However, they can also have adverse effects.

Other systemic medications that aim to treat the whole body include retinoids — a form of vitamin A — and cyclosporine. A person may take them by mouth or as an injection.

Psoriasis can occur on the skin anywhere on the body. It most often develops on the knees, elbows, or scalp.

The most common type is plaque psoriasis. This starts out as small red or discolored bumps that grow larger and form a scale.

However, other types, such as scalp, nail, inverse, and guttate psoriasis, may appear differently.

Generally, a psoriasis rash may appear as inflamed, itchy, flaky, cracked, and thickened patches of skin.

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