Psoriasis is a life-long 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 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 on the skin.

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 inside. It is not contagious, which means that one person cannot pass psoriasis to another.

There are several different types of psoriasis that can have different symptoms. However, the symptoms and types often overlap.

Plaque psoriasis

What is this rash?Share on Pinterest
What is this rash? Psoriasis can take many forms.

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

A plaque psoriasis rash consists of red patches of plaque which has a silvery-white coating of scale.

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

Scalp psoriasis

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.

There will be:

  • flakes form that may look like dandruff
  • red, itchy, and thickened skin
  • cracking of the skin
  • hair loss, in more severe cases

Anyone who has scalp psoriasis should 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 reduce these risks.

Nail psoriasis

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

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

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

Find out more here about how psoriasis can affect the nails.

Pustular psoriasis

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.

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

The person may also experience fever, chills, weak muscles, little appetite, extensive itching, and tiredness.

Inverse psoriasis

This form leads to red, shiny, and sore skin in areas where skin is in contact with skin, or skin folds.

These include:

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

Find out more about inverse psoriasis here.

Guttate psoriasis

Guttate psoriasis often develops after an illness, such as strep throat. It will affect around 10 percent of people with psoriasis at some time, according to the National Psoriasis Foundation.

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

Learn more about guttate psoriasis here.

Erythrodermic psoriasis

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:

  • very red 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 reacted to severe sunburn, are taking particular medications, or have another form of psoriasis that has been left untreated or controlled can develop erythrodermic psoriasis.

Find out more here about erythrodermic psoriasis.

Here are some pictures to show what different types of psoriasis look like.

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 patches of skin, with silvery spots
  • small red 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 improve or disappear for a time.

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

The following factors can trigger a flare-up of psoriasis:

  • stress
  • skin injury
  • smoking or exposure to smoke
  • infections
  • medications, such as lithium, beta-blockers, iodides, and antimalarials
  • cold temperatures
  • exposure to smoke
  • heavy use of alcohol

The severity of psoriasis varies between individuals and depends on the type of psoriasis a person has.

Psoriasis on the face and around the eyes can be challenging because the skin is very sensitive in this area. People must take great care with treatment, even with mild cortisone creams. Some people may find that severe psoriasis causes stress and depression.

Psoriasis may also develop on the eyes, in the ears, and around the mouth and nose.

When psoriasis affects the hands and feet, swelling, blisters, and cracking may follow. Severe nail psoriasis can cause the fingernails or toenails to crumble and fall off. All of these symptoms can cause pain. Sometimes, symptoms are so severe, that people find it difficult to walk or use their hands.

Scalp psoriasis ranges from mild to severe. Infections and hair loss may occur. The hair usually grows back after a flare is over.

Inverse psoriasis affects some of the body's most sensitive skin, including the genital area, which can be very painful. As it occurs in skin folds, sores can also develop, which typically require additional treatment.

The following complications can occur with psoriasis:

Psoriatic arthritis is a complication that usually develops in someone who already has psoriasis but may not have any skin symptoms. It often affects the joints closest to the fingernails and toenails.

Cardiovascular disease, diabetes, and high blood pressure may occur alongside a severe case of psoriasis. These are signs of metabolic syndrome.

Onychomycosis is a fungal infection that can affect people with psoriasis. It can resemble nail psoriasis, but it is a different diagnosis. The nails thicken and may crumble or fall off.

Psoriasis also seems to increase the risk of developing other serious health conditions. These include other autoimmune diseases, depression, kidney problems, and Parkinson's disease.

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Ringworm is a fungal infection with a distinctive pattern. Image credit: Grook da Oger, 2008.

Other conditions can cause a rash that people might confuse with psoriasis, include:

Eczema: Eczema is a skin disorder 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. It 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 bumps anywhere on the skin, including the genitals and the scalp, or as white dots in the mouth. Click here to find out more.

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 grey. 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. Click here for more information.

Seborrheic dermatitis: is an itchy, red skin condition usually found on the scalp and other oily areas of the body. Find out more here.

People should see a doctor if a skin rash lasts longer than a few days, if it interferes with their quality of life, or if there are other symptoms, such as a fever.

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 impacts the individual.

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

These drugs affect the way the immune system works. They can reduce 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.

Some common approaches include:

  • Exposure to sunlight, starting with 5–10 minutes and building up as the skin tolerates exposure
  • Soaking in an oatmeal bath
  • Using thick, fragrance-free moisturizers to keep the skin from cracking
  • Covering rash areas
  • Rest
  • Stress reducing interventions, such as yoga or meditation
  • Lotions and creams, such as coal tar ointments, topical steroids, and compounds based on vitamin D or vitamin A

It is important to seek medical treatment, as psoriasis can affect a person's quality of life. Without treatment, symptoms can worsen, and there may be complications.

A doctor will also advise about suitable home remedies.