10 June 2014

Psoriasis: types and triggers

Some facts about psoriasis

  • It's estimated that at least 2% of the world's population has psoriasis.
  • Psoriasis is a systemic disease.
  • People who get psoriasis exhibit a wide range of symptoms that vary in severity.
  • Psoriasis goes through cycles: sometimes better, at other times worse.
  • No single treatment works for everyone.
  • A form of arthritis, called psoriatic arthritis, affects up to 42% of the people who have psoriasis.
  • Poor diagnosis and treatment means that many people with psoriasis and psoriatic arthritis suffer in silence.
  • There is no cure for psoriasis or psoriatic arthritis.

What are the symptoms?

Normally there is a constant shedding of dead skin cells. However, due to the acceleration of the replacement process, both dead and live cells accumulate on the skin surfce. Often this causes red, flaky, crusty patches covered with silvery scales that shed easily. It can occur on any part of the body, although it is most commonly found on the elbows, knees and the scalp. It can also cause intense itching and burning.

Who is at risk?

Psoriasis affects approximately 2% of people globally, and up to 4% in some countries. It can start at any age. The condition is not contagious and many people only have small patches of their skin affected. There is a genetic link and psoriasis tends to run in families. About 30% of people with one first degree relative with psoriasis develop the condition. This genetic tendency appears to be triggered by infection; certain medicines (including ibuprofen and lithium); psychological factors (including stress), or skin trauma. There is no way of predicting who will develop psoriasis. 50-60% of people who first experience it do not know of anyone else in their family who has had it.


Psoriasis runs in families. One in three people with psoriasis has a close relative with the condition. However, the exact role that genetics plays in causing psoriasis is unclear. Research studies have shown many different genes are linked to the development of psoriasis. It is likely that different combinations of genes may make people more vulnerable to the condition. However, having these genes does not necessarily mean you will develop it.

Common types of psoriasis

Plaque psoriasis

This is the most common form, accounting for about 90% of cases. Its symptoms are dry, red skin lesions, known as plaques, which are covered in silver scales. They normally appear on your elbows, knees, scalp and lower back but can appear anywhere on your body. The plaques can be itchy, sore or both. In severe cases, the skin around your joints may crack and bleed.

Scalp psoriasis

This can occur on parts of your scalp or on the whole scalp. It causes red patches of skin covered in thick silvery-white scales. Some people find scalp psoriasis extremely itchy, while others have no discomfort. In extreme cases it can cause hair loss, although this is usually only temporary.

Nail psoriasis

In about half of all people with psoriasis, the condition affects the nails. Psoriasis can cause your nails to develop tiny dents or pits, become discoloured or grow abnormally. Often nails can become loose and separate from your nail bed. In severe cases, your nails may crumble.

Guttate psoriasis

Guttate psoriasis causes small (less than 1cm or 1/3 inch) drop-shaped sores on your chest, arms, legs and scalp. There is a good chance that guttate psoriasis will disappear completely after a few weeks, but some people go on to develop plaque psoriasis. This type of psoriasis sometimes occurs after a streptococcal throat infection and is more common among children and teenagers.

Less common types of psoriasis

There are less common types of psoriasis:  Inverse (flexural) psoriasis, pustular psoriasis, Generalised pustular (von Zumbusch) psoriasis, Palmoplantar pustular psoriasis and acropustulosi. In very rare cases, erythrodermic psoriasis may develop.

What triggers the disease?

Many people's psoriasis symptoms start or become worse because of a certain event, known as a trigger. Knowing your triggers may help you to avoid a flare-up. Common triggers include:

  • An injury to your skin such as a cut, scrape, insect bite or sunburn (this is known as the Koebner response)
  • Drinking excessive amounts of alcohol
  • Smoking
  • Stress
  • Hormonal changes, particularly in women (for example during puberty and the menopause)
  • Certain medicines such as lithium, some antimalarial medicines, anti-inflammatory medicines including ibuprofen, ACE inhibitors (used to treat high blood pressure) and beta blockers (used to treat congestive heart failure)
  • Throat infections - in some people, usually children and young adults, a form of psoriasis called guttate psoriasis (which causes smaller pink patches, often without a lot of scaling) develops after a streptococcal throat infection, although most people who have streptococcal throat infections do not develop psoriasis
  • Other immune disorders, such as HIV, which cause psoriasis to flare up or to appear for the first time

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