Coal Tar for Psoriasis

Century-old remedy remains a safe and viable treatment

Dermatology consultation woman
B. Boissonnet / Getty Images
In This Article

Coal tar is a byproduct of coal processing that has been used for more than a century to treat skin problems. Today, it is considered an effective, safe, and inexpensive topical treatment for plaque psoriasis. Available in different strengths and formulations, coal tar is included on the World Health Organization (WHO)'s List of Essential Medicines. It has also been approved by the U.S. Food and Drug Administration (FDA) under the classification "generally recognized as safe and effective" (GRASE).

Coal tar was first discovered around 1665 and used for medical purposes as early as the 1800s.

Effectiveness

Coal tar belongs to a class of drugs called keratoplastics, which also include benzoyl peroxide, tretinoin, and salicylic acid. It works by directly interfering with the synthesis of DNA in the skin. This action can help slow the abnormal buildup of skin cells and decrease the size of psoriatic plaques.

Coal tar also promotes the shedding of dead cells from the top layer of skin, known as the stratum corneum. This can help reduce dandruff as well as itchiness and scaling. Coal tar is especially useful in treating scalp psoriasis and hard-to-treat palmoplantar psoriasis (psoriasis of the palms and soles).

A 2014 study in the Indian Journal of Dermatology reported that a 12-week course of coal tar paired with salicylic acid was just as effective in relieving plaque psoriasis as the prescription drugs calcipotriol and betamethasone.

Side Effects

Over-the-counter (OTC) coal tar products are considered safe if used in concentrations between 0.5% and 5%. More potent coal tar is more likely to cause irritation and dryness. These side effects can be minimized by applying moisturizer before the coal tar preparation.

Coal tar can make the skin extra-sensitive to sunlight, often for up to 24 hours after application. To avoid sunburn, wash your skin thoroughly after a coal tar treatment and apply a high-SPF sunscreen if you plan to be outdoors.

Coal tar can also stain clothes, towels, bedding, and even light-colored hair. It often helps to apply the preparation in the shower and to wash and rinse it off thoroughly afterward. Any discoloration of hair will usually return to normal after a few shampoos. Newer liquor carbonis distillate (LCD) coal tar products are less likely to stain light or color-processed hair.

While certain compounds in coal tar are considered carcinogenic (cancer-causing), the level in a 0.5% to 5% preparation is thought to be negligible.

According to the FDA, there is no evidence that "the risk of cancer is greater in consumers who regularly use OTC drug products containing coal tar than in consumers who do not."

There are also no known drug interactions associated with coal tar. Allergic reactions are rare, but may occur. If you are prone to allergies, patch test the product on a small area of skin and wait 24 hours to see if a rash develops.

Call 911 or seek emergency care if you experience hives, difficulty breathing, chest tightness, irregular heartbeats, dizziness, or the swelling of the face, tongue, or throat after using coal tar.

Products and Formulations

Coal tar is found in a plethora of OTC shampoos, as well as creams, gels, and bath additives. Compound pharmacists can mix crude coal tar (which has a black, paste-like texture) or an alcohol-based coal tar solution with all sorts of bases, including steroid creams and ointments.

The dosage varies by the strength of the preparation. To avoid side effects, follow the instructions on the product label or ask your pharmacist for advice. Topical coal tar products should be massaged into the skin and allowed to dry.

Coal tar products intended for baths or foot soaks should be mixed thoroughly and used for around 10 to 15 minutes. Take extra care when using coal tar in bathtubs or showers as it can make surfaces extremely slippery.

Coal tar is intended for use external only. Take special care when applying coal tar to face; avoid getting any into the eyes, nostrils, and mouth. The same applies to the rectum, vagina, or urethra. If you accidentally get coal tar in the eyes or other delicate tissues, rinse thoroughly with cool water for 15 minutes.

Coal tar preparations should never be applied to inflamed, broken, or infected skin. Doing so may cause pain and trigger a psoriatic flare.

Coal tar is sometimes used with phototherapy to sensitize the skin to ultraviolet (UV) radiation. This should only be performed by a dermatologist who is trained to deliver the correct dose using specialized phototherapy equipment. Never use a tanning bed or lamp to treat psoriasis as it is more likely to cause skin damage or trigger a flare.

For safety, coal tar should only be used in children under the direction of a dermatologist.

What to Look For

There are literally hundreds of different coal tar preparations found on drugstore shelves and online. When choosing a product, opt for one that has undergone testing with an independent certifying body like the U.S. Pharmacopeia (USP), NSF International, or ConsumerLab. In this way, you will know for sure that the product contains the ingredients listed on the label in the declared potency level.

Was this page helpful?

Article Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial policy to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. World Health Organization. Coal Tar. Geneva, Switzerland; 1997.

  2. Ahmed A, Danish M. Coal Tar Burn in Emergency Room. Int J Advances Med Sci. 2017 Jan;2(1):1-5.

  3. Sekhon S, Jeon C, Nakamura M, et al. Review of the mechanism of action of coal tar in psoriasis. J Dermatolog Treat. 2018;29(3):230-2. doi:10.1080/09546634.2017.1369494

  4. Khandpur S, Sahni K. An open-label prospective randomized trial to compare the efficacy of coal tar-salicylic acid ointment versus calcipotriol/betamethasone dipropionate ointment in the treatment of limited chronic plaque psoriasis. Indian J Dermatol. 2014:59(6):579-83. doi:10.4103/0019-5154.143523

  5. U.S. Food and Drug Administration. Docket No. 000-1210. Comments No. CP1, C1, and C2. February 27, 2001.

Additional Reading