Coal tar preparations
Coal tar preparation has been used for over a hundred years in dermatology. It is a topical treatment mostly used for acute scalp psoriasis.
Coal tar is a thick heavy oil (usually a brown or black liquid). It is a by-product of coal when coal is carbonised to make coke or gasified to make coal gas. Coal tar contains many different chemicals and can decrease itchiness from skin conditions such as psoriasis.
It is not clear how coal tar works, however it appears to exert its anti-psoriasis benefits by interfering with DNA and thus slowing down skin cell growth and turnover. The long term result is thinning of the psoriatic plaques. In addition, it reduces inflammation and has anti-scaling properties.
Coal tar can be used in medicated shampoos, soaps and ointments to assist in the treatment of psoriasis. Creams, ointments, lotions, pastes, scalp treatments, bath additives and shampoos that contain coal tar are widely available.
Scale lifters are used on the hair/scalp to treat dandruff and other scaly, itchy skin conditions such as psoriasis or seborrheic dermatitis. They work by causing the skin to shed dead cells from its top layer and slow down the growth of skin cells - this decreases scaling and dryness.
Scalp products contain the highest levels of coal tar available without a prescription. They penetrate to relieve the annoying itching and flaking and helps stop these symptoms from coming back. They should be used at least twice a week or as directed by a physician.
These can be beneficial in treating psoriasis. Adding oil, oatmeal, Epsom salts or Dead Sea salts in a bath can help remove psoriasis scale and soothe itching. Soak for around 15 minutes and apply a moisturizer or oil to the skin immediately after getting out of the bath.
Keeping the skin lubricated on a daily basis is an important part of psoriasis care because it reduces redness and itching and helps the skin heal. Dermatologists recommend heavy creams and ointments to lock water into the skin. Here are some quick tips for keeping your skin moisturised:
- Use fragrance free products
- Apply moisturisers after showering and after washing your hands
- Wash with moisturising soaps
- Limit your lukewarm showers to 10 minutes or less
You should avoid using coal tar to treat psoriasis if:
- the skin is broken or very inflamed
- the skin is infected
- you have pustular psoriasis
- psoriasis has come on acutely and suddenly
- during the first three months of pregnancy
- you are exposed to sunlight - this is because it may make your skin react to the sunlight, causing a rash - if you do go out in the sun, cover up with clothing and use a sun-block cream or lotion
Coal tar is often combined with another treatment for psoriasis, such as a steroid or salicylic acid, so that both can be given together in the same preparation.
Some coal tar preparations may stain skin, hair, clothes and fabrics.
Contact of coal tar products with normal skin is not normally harmful. Therefore, coal tar creams can be used liberally and can be used for both large patches of psoriasis, and for widespread small patches. However, in some people coal tar can cause skin irritation, a contact allergy, sterile folliculitis (pus-filled spots at the base of the hairline) or an acne-like rash.
Many applications can be purchased over the counter although it is always advisable to seek advice from your GP before using coal tar products.
Sources used in writing this article are available on request
Information contained in this Articles page has been written by talkhealth based on available medical evidence. Our evidence-based articles are certified by the Information Standard and our sources are available on request. The content is not, though, written by medical professionals and should never be considered a substitute for medical advice. You should always seek medical advice before changing your treatment routine. talkhealth does not endorse any specific products, brands, or treatments.
Information written by the talkhealth team
Last revised: 9 January 2018
Next review: 9 January 2021