User:Mr. Ibrahem/Coal tar

Coal tar is a thick dark liquid which is a by-product of the production of coke and coal gas from coal. It has both medical and industrial uses. It may be applied to the affected area to treat psoriasis and seborrheic dermatitis (dandruff). It may be used in combination with ultraviolet light therapy. Industrially it is a railway tie preservative and used in the surfacing of roads.

Side effects include skin irritation, sun sensitivity, allergic reactions, and skin discoloration. It is unclear if use during pregnancy is safe for the baby and use during breastfeeding is not typically recommended. The exact mechanism of action is unknown. It is a complex mixture of phenols, polycyclic aromatic hydrocarbons (PAHs), and heterocyclic compounds. It demonstrates antifungal, anti-inflammatory, anti-itch, and antiparasitic properties.

Coal tar was discovered around 1665 and used for medical purposes as early as the 1800s. It is on the World Health Organization's List of Essential Medicines. Coal tar is available as a generic medication and over the counter. In the United Kingdom 125 ml of 5% shampoo costs the NHS about £1.89. In the United States a month's treatment costs less than $25 USD. Coal tar was one of the key starting materials for the early pharmaceutical industry.