Short Contact Dithranol for Psoriasis

What is psoriasis?

Psoriasis is a common skin condition which commonly develops as patches ('plaques') of red, scaly skin. Treatment aims to clear the rash as much as possible. However, as psoriasis tends to 'come and go', you may need courses of treatment 'on and off' throughout your life. There are various treatments. There is no 'best buy' that suits everybody. The treatment advised by your doctor may depend on the severity, location and type of psoriasis. Also, one treatment may work well in one person, but not in another.

This leaflet is just about dithranol for the treatment of psoriasis. There are separate leaflets on psoriasis in general, and on the other common topical treatments for psoriasis - vitamin D analogues, coal tar, steroid creams and tazarotene.

What is dithranol and short contact dithranol treatment?

Dithranol is a drug that has been used in the treatment of psoriasis for over 50 years. There are various ointments and creams that contain different strengths of dithranol. Dithranol is usually a safe treatment and will clear psoriatic plaques in many people with psoriasis.

As a rule, dithranol is only used to treat the classical plaques (larger patches) of psoriasis. It is not usually suitable for widespread small patches of psoriasis that some people develop. Also, it should not be used in the skin creases or flexures (front of elbows, behind knees, armpits, groins, etc) or on the face unless supervised by a specialist. This is because of the risk of irritating the skin in the skin creases and irritating the eyes with dithranol.

Dithranol can irritate if it comes into contact with normal skin around treated patches of psoriasis. It can also stain clothing and fabrics that come into contact with it. These problems can be minimised if dithranol is used for a short period every day ('short contact') and the strength is gradually increased so that the skin becomes used to the treatment.

How to use dithranol for short contact treatment

Follow the instructions given by your doctor carefully, and on the packet of the preparation that you are prescribed. Also, persevere with the treatment as success often takes several weeks. The instructions may include the following:

• Wear plastic disposable gloves when applying dithranol cream or ointment. Wash hands thoroughly after applying dithranol.
• Apply only to the plaques of psoriasis. Avoid putting it on normal skin. For creams, apply sparingly, rub in well and wipe off any excess. For ointments, apply sparingly.
• Avoid getting any in or near the eyes. If eye irritation occurs wash thoroughly with water and if it persists, see your doctor.
• Leave the cream or ointment on for as long as directed by your doctor. For short contact treatment, this may be anything from 5-60 minutes. Then wash it off.
• When washing off, just use cool water (below 30C) without soap or detergent. Hot water or soap may cause increased staining of the skin by the dithranol. You can use hot water and soap to wash after the cream or ointment has been rinsed off.

A common treatment plan is to start with 0.1% dithranol. If there is no irritation then apply daily as directed (often for about 30 minutes each day) for a few days. The strength is then increased to a 0.25% preparation which is continued for a further few days before moving on to a higher strength, etc. The aim is to gradually build up the strength (the % concentration) to the strongest preparation you can tolerate. The strongest of the brands that can be prescribed is 3%. However, hospital skin departments (dermatology departments) sometimes use even higher strengths in some severe cases.

If irritation or burning occurs, stop using dithranol and apply a moisturiser until the skin has settled. Then start again at a lower strength. Some people are more sensitive to the irritating and burning effects than others. So, different people end up using different strengths.

Carry on with the treatment until the treated skin feels flat and smooth like the nearby normal skin. Any staining of the skin will clear, usually in about two weeks. If you have problems with skin irritation, or if there is no improvement after three weeks at the highest strength you can tolerate, then see your doctor for advice.

Dithranol can stain

Dithranol stains normal skin a brownish colour. This is temporary and will gradually fade. It may also stain clothes, sheets, furnishings, etc, if they come into contact with dithranol. This staining can be permanent. So, when using dithranol, wear old clothes that you don't mind if they become stained.

Baths may also be stained. If possible, have a shower rather than a bath after using dithranol treatment. If you have a bath, clean it immediately with detergent. A little vinegar added to rinse water helps to reduce staining.

If staining of the skin occurs in the centre of the plaques of psoriasis, this means the psoriasis is starting to clear.

How safe is dithranol?

Although during treatment dithranol may irritate or slightly burn normal skin, and may stain skin or clothes, it is generally a safe treatment. It has been used for many years and, if used properly, is not known to cause any long term side-effects or problems.

Further sources of information

Psoriasis Association

Dick Coles House, 2 Queensbridge, Bedford Road, Northampton NN4 7BF
Tel (helpline): 0845 6 760 076
Web: www.psoriasis-association.org.uk