Psoriasis

What is it and who gets it

This a common rash which results in angry, red, scaly patches on the skin. Skin continuously regenerates from the lower layers of the skin, moving upwards to the surface. In unaffected people it takes 28 days for the newly formed skin cells to reach the upper layer of skin, in psoriasis this is reduced to 7 days, leading to a build up of thickened, flaky skin. There are also more blood vessels in the affected skin which is why it looks so red.

The cause of this is not well understood, but a genetic element may make people more prone to developing the condition, perhaps being triggered off by a viral illness.

It usually occurs between the ages of 15-30 or after the age of 40 years. Males and females are equally affected, but it is more common in white people.

3 in 10 people have an affected family member.

We do know it is more common in smokers.

It is not contagious or cancerous and is it not an infection or an allergy. It is diagnosed by its appearance and tests are not usually required to confirm the diagnosis.

The severity of symptoms may vary greatly from a few barely noticeable small patches to large areas of the skin being affected.

Aggravating factors

In most cases no aggravating trigger is obvious although the following factors are known to cause a flare-up in some people:

Stress

Smoking increases resistance to treatment

Bacterial sore throats

Medication –The rash may occur several months after the start of the medication.

  • Beta blockers like atenolol and propranolol
  • Antimalarial medication
  • Lithium
  • Anti-inflammatory pain-killers such as ibuprofen, diclofenac, naproxen etc
  • ACE inhibitors such as ramipril, lisinopril etc are used for the treatment of high blood pressure and certain heart and kidney conditions

Trauma- scratches and scars can become affected.

Sunshine - is beneficial in most people but in a few can exacerbate psoriasis. A severe sunburn can worsen psoriasis.
Hormonal changes- women may find that their psoriasis is worst during puberty and menopause. Pregnant women may find that their psoriasis improves, but that it flares in the months after the baby is born.

Alcohol - aggravates the condition and increases resistance to treatment.

Different types of psoriasis

Plaque psoriasis

Affects typically the elbows, knees, lower back and scalp. These are red patches with scaling over the top. This is the most common type affecting 90% of people with the condition. The armpit, breast and groin creases can also be affected.

Pustular Psoriasis

These are sore fluid filled spots that affect the palms and/or the soles of the feet. It is not usually associated with a rash. If it is, an urgent specialist opinion should be sought. This is the second most common type of psoriasis.

Guttate psoriasis

Usually follows a sore throat caused by bacteria. There are multiple small (around 1cm) patches which can affect the whole body. These tend to resolve naturally after a few weeks but can persist for 4 months. In some patients they do not resolve.

Nail psoriasis

This is usually associated with a rash, but can occur alone. You may see pinhead size indentations on the nail. The nail may also loosen from the nail bed.

Erythrodermic psoriasis

This is when more than 95% of the body’s surface area is covered with psoriasis. This can lead to large amounts of water loss from the skin, resulting in difficulty controlling the body’s temperature and risk of severe infection. This will need urgent assessment in hospital.

Treatment

There is no cure for psoriasis, but the aim of treatment is to reduce the rash as much as possible. However the condition may flare up from time to time and you may need repeated courses of treatment.

Emollients

Heavy moisturisers or emollients should be used daily even when the skin is calm. They will reduce itching and scaling of the skin and also make other treatment creams penetrate into the patches better.

Treatment creams and shampoos

One or a combination of these products will be prescribed by your doctor depending on the type, site and severity of your psoriasis.

Vitamin D creams ( Dovonex, Silkis, Curatoderm)

These usually work well and are commonly used. They slow down the rate at which the skin is formed. They are usually easy to apply and not smelly. There is a calcipotriol scalp application also. They are also used as combination creams with steroids eg dovobet.

Steroid creams

These are also commonly used and work by reducing redness and irritation. Both skin and scalp steroid preparations are available. They are usually recommended for a limited duration and use for more than 4 weeks should be after review with a doctor. There are different strengths of steroid creams and ointments and your doctor will recommend the right one depending on the severity and site of the psoriasis.

Coal Tar products

These products reduce redness and scaling. They are available as creams, lotions, pastes, scalp treatments and shampoos as well as bath additives.

They can have an unpleasant smell and discolour clothing. They can also cause skin irritation in some people and your skin can be sensitive to sunlight whilst using them. They should not be used in the first 3 months of pregnancy.

Dithranol cream

This has been used for a long time to treat psoriasis. If used every day it will usually help. One of its main problems is that it irritates the surrounding normal skin, so it is important to apply it to the affected patches only, with gloves on. It should not be used on the face unless recommended by a specialist.

Short contact dithranol is popular. High strength dithranol cream is applied for 5-60 minutes and then washed off.

It may stain your skin, clothes and bedding.

Salicylic acid paste

This is often used to lift the scale from the affected area so that the treatment creams like steroids and coal tar can penetrate it better. It can cause skin irritation in some people.

Scalp psoriasis

A coal tar shampoo is usually tried first and is often quite effective. It can be combined with a salicylic acid preparation, coconut oil/salicylic acid preparation, a steroid preparation, calpotriol preparation or a combination of more than one of these. Your doctor will be able to advise you.

Hospital based treatments include light treatment and medication by mouth in patients with psoriasis which is extensive or resistant to treatments with creams.

For further help and advice:

Psoriasis Association
Dick Coles House, 2 Queensbridge, Northampton, NN4 7BF
Tel (helpline): 0845 676 0076
www.psoriasis-association.org.uk

PAPAA - The Psoriasis and Psoriatic Arthritis Alliance
PO Box 111, St Albans, Hertfordshire, AL2 3JQ
Tel: 01923 672837
www.papaa.org
Provides support and information for people with psoriasis and psoriatic arthritis.

References

Patient UK
Primary Care Dermatology Society
British association of Dermatologists