What is psoriasis?
Psoriasis is a common condition where there is inflammation of the skin. It typically develops as patches (plaques) of red, scaly skin. Once you develop psoriasis it tends to come and go throughout life. A flare-up can occur at any time. The frequency of flare-ups varies. There may be times when psoriasis clears for long spells. However, in some people flare-ups occur often. Also, the severity of psoriasis varies greatly. In some people it is mild with a few small patches that develop and are barely noticeable. In others, there are many patches of varying size. In many people the severity is somewhere between these two extremes.
There is no once-and-for-all cure for psoriasis. 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 treatment 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 for one person, but not for another.
This leaflet is just about dithranol treatment for psoriasis. See separate leaflet called ‘Psoriasis’, which discusses psoriasis in general. See also other leaflets discussing some other common treatments for psoriasis, called‘Vitamin D Analogues for Psoriasis’ and ‘Coal Tar for Psoriasis’.
What is dithranol and short contact dithranol treatment?
Dithranol has been used in the treatment of psoriasis for over 50 years. It is actually made from a tree bark extract. There are various ointments and creams that contain different strengths of dithranol. A scalp gel that contains dithranol is also available. Dithranol is usually a safe treatment and will clear skin 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 on skin creases or flexures (front of elbows, behind knees, armpits, groins, etc) or on your face unless supervised by a specialist. This is because of the risk of irritating this skin and irritating your eyes.
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. Short contact refers to the fact that you apply the dithranol to you skin for a short period of time (usually between 5 and 60 minutes) and then wash it off.
Occasionally, dithranol is left on the skin for a longer time (sometimes overnight) but this is done under the supervision of a skin specialist and often specialist nurses will apply the dithranol.
The following are some general points that aim to complement (not to replace) the instructions that come with the preparation that you are prescribed.
How to use dithranol for short contact treatment
Follow the instructions given by your doctor carefully, and those that come with 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, your 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. Note: creams containing dithranol may wash off more easily than ointments.
- When washing off, just use cool water (below 30°C) 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 yourself after the cream or ointment has been rinsed off.
A common treatment plan is to start with the lowest strength preparation of dithranol (0.1%). If there is no irritation, then apply once daily as directed (often for about 30 minutes each day) for about a week. If needed, the strength may then be increased to a stronger preparation which is continued for a further week or so before moving on to a higher strength, etc. In general, the aim is gradually to build up the strength (the % concentration) of dithranol that you use. The highest strength of dithranol usually used is 2%. It may take around four weeks to build up the strength. However, not all people need this highest strength. The best strength of dithranol to use varies from person to person. It depends on the thickness of your psoriasis plaques, how much irritation and burning you get, etc.
If irritation or burning occurs, stop using dithranol and apply a moisturiser until your skin has settled. Then start again at a lower strength. Some people are more sensitive to the irritating and burning effects than others.
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.
If you are also using an emollient (a moisturiser) for your psoriasis, you should use this first and then wait for 30 minutes before you apply dithranol.
Treatment with dithranol is usually carried on until the treated skin feels flat and smooth like your nearby normal skin. Your doctor will advise how long you should continue the treatment for. It may take up to six weeks for you to notice a good improvement in your psoriasis.
Dithranol can stain
Dithranol stains normal skin a brownish colour. Your hair may also be stained. This staining is temporary and will gradually fade, usually in about two weeks. Dithranol may also stain clothes, sheets, furnishings, etc, a brown colour if they come into contact with it. This staining can be permanent. So, when using dithranol, wear old clothes that you don’t mind becoming stained.
Baths may also become 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?
As mentioned above, during treatment dithranol may irritate or slightly burn normal skin and it may stain skin or clothes. But, despite this, 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.
Is there anyone who should not use dithranol?
Dithranol should not be used by people with pustular psoriasis. It should also not be used if your psoriasis is inflamed or if psoriasis comes on acutely (suddenly).
No studies have been published that look at the safety of dithranol during pregnancy or if you are breast-feeding. However, so far, no problems have been reported when dithranol has been used during pregnancy or breast-feeding.
Further sources of information
PAPAA – The Psoriasis and Psoriatic Arthritis Alliance
PO Box 111, St Albans, Hertfordshire, AL2 3JQ
Tel: 01923 672837 Web: www.papaa.org
Provides support and information for people with psoriasis and psoriatic arthritis.
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