Crude Coal Tar

Alternative names: Coal tar.

Coal tar is a messy and smelly – but effective – topical treatment for various skin conditions.  It can also stain clothing and irritate the skin.  However, coal tar products that are on the market now are much easier to use than they once were.

Source

Crude coal tar is obtained by the destructive distillation of bituminous coal at very high temperatures.  It is believed that over 10,000 different compounds make up coal tar but only a few hundred have been identified.  The main groups of compounds making up crude coal tar are 48% hydrocarbons, 42% carbon and 10% water.

In its natural form coal tar is a thick, nearly black, viscous liquid with a characteristic smell.  It is most often obtained in solution form (ranging in strength from 0.1 to 20%) and mixed with other ingredients, such as salicylic acid and sulfur, to make lotions, creams, ointments and shampoos.

Crude and refined coal tar preparations should still be available through a pharmacist who will compound any coal tar preparation as prescribed by a doctor.

Function; Why it is Recommended

Exactly how coal tar works to treat various health conditions is not completely understood.  It appears to have antimicrobial, antipruritic (reduce itching) and keratoplastic (normalize keratin growth in the skin and reduce scaling) effects.

Crude Coal Tar has been used for decades to help treat the scaling, itching and inflammation of psoriasis, eczema, and other skin disorders.

Coal tar is still used to treat a variety of skin disorders, particularly conditions where the skin is flaky and scaly:

• Scalp psoriasis
• Palmoplantar pustulosis
• Plaque psoriasis
• Atopic dermatitis.

Instructions

Tips for using coal tar products:

• Apply it at bedtime if possible to avoid daytime inconvenience of the smell and staining
• Leave on skin for at least 2 hours unless otherwise directed by your doctor
• If treating the scalp, apply with a downward stroke in the same direction as hair growth
• Cover or wrap with bandages to help the preparation stay in place and prevent staining.  Do not use plastic wrap as this may cause irritation and infection
• Do not apply to infected, blistered, raw or oozing areas of the skin
• After applying coal tar preparations, protect the treated area from direct sunlight and do not use a sunlamp unless otherwise directed by your doctor.

Side-Effects

Most patients tolerate coal tar preparations well.  It may initially cause mild stinging or skin irritation as your body gets use to the medicine.  However, if this continues stop using the preparation and see your doctor.

When used on the scalp, it may temporarily discolor bleached, tinted, light blond or grey hair.  Coal tar also stains skin and clothing.  The stain on the skin will wear off after you have stopped using the preparation.

Coal tar may cause photosensitivity, hence the need to stay out of direct sunlight when using these preparations.  In some instances your doctor may use the Goeckerman regimen, which is a combination of coal tar with UVB phototherapy.  This has been found to be particularly successful for treating psoriasis.

There is some controversy over the carcinogenic (cancer-causing) potential of coal tar.  In animal studies, it has been shown to increase the chance of skin cancer.  However, in human studies using safe doses, an increase in the incidence of cancers has not been found after 75 years of documented use.  It's safe to use coal tar if you follow your doctor's instructions.