What is coal tar and what is it used for?
In its natural form, tar is a thick, nearly black liquid with a characteristic smell. It is obtained through distillation from coal, wood or petroleum and contains a mixture of hydrocarbons, phenols and other compounds.
Tar has been used to treat various skin disorders since ancient times. Currently, coal tar is used to treat scalp psoriasis, stable plaque psoriasis, seborrhoeic dermatitis (dandruff) and sometimes atopic eczema. It is not completely understood how coal tar works to treat these conditions. Topical application of coal tar appears to normalise keratin growth in the skin and reduce scaling, and it appears to reduce itching as well.
Coal tar preparations can be a useful part of a psoriasis treatment regimen. As with all topical treatments, it may take a number of weeks for the coal tar treatment to show benefit.
Marketed preparations of coal tar in the UK include: coal tar creams (Exorex Lotion) and coal tar shampoos and scalp applications (Alphosyl 2 in 1 shampoo, Polytar shampoo, Neutrogena T/Gel shampoo, ArtNaturals Scalp 18).
How to use coal tar preparations?
Follow closely the instructions on the label on how to use your coal tar preparation. Here are some general tips for using coal tar products.
- Apply it at bedtime if possible to avoid daytime inconvenience of the smell and staining
- Wrap with bandages to help the preparation stay in place and prevent staining. Do not use plastic wrap as this may cause irritation.
- Do not apply to infected, blistered, raw or oozing areas of the skin
- After applying tar preparations, protect the treated area from direct sunlight and do not use a sunlamp unless otherwise directed by your doctor.
What are the possible side-effects?
Coal tar preparations can irritate the skin, particularly on initial use. They can be messy (staining skin, hair and clothing), and often have an associated odour.
Sunlight can interact with tar on the skin to cause a sunburn-like contact phototoxic dermatitis.
What are the precautions for the use of coal tar preparations?
Coal tar preparations should not be used during severe flare-ups of psoriasis.
During pregnancy, coal tar preparations could be used on small areas of skin (scalp) and for a short period only. Same precautions while breastfeeding and not to be applied to the chest.