Psoriasis treatment: Coal tar

• It costs less than most psoriasis treatments

• It can be used long term

Why do dermatologists prescribe coal tar for psoriasis?

Coal tar can effectively treat:

• Plaque-type psoriasis

• Itch

• Scalp psoriasis (especially if itch is the main symptom)

• Difficult-to-treat psoriasis on the palms and soles

• Scale

Your dermatologist may prescribe coal tar alone or include it as part of a treatment plan that includes other medicines, phototherapy, or both.

Safety and effectiveness

Safety: Dermatologists have been prescribing coal tar for more than 100 years to treat psoriasis, and it is considered safe for long-term use.

Like all medicines, some patients should avoid coal tar. Women who are pregnant or breastfeeding may want to use a different treatment. We have too little information about how coal tar can affect an unborn baby or a child who is nursing. 

People who are sun sensitive or take medicine that makes them more sensitive to ultraviolet (UV) light should also use a different treatment.

Effectiveness: Coal tar can be very effective. Some people see complete clearing with coal tar and long remissions (time without psoriasis). 

Many patients who have difficult-to-treat psoriasis on their palms and soles (palmoplantar psoriasis) see clearing when they use coal tar along with a corticosteroid that they apply to their psoriasis. 

Dermatologists also include coal tar in a treatment plan for patients who have scalp psoriasis. Coal tar can clear scalp psoriasis and increase remissions on the scalp. 

How well coal-tar products work varies. You cannot always tell which product will work best by looking at how much coal tar the product contains. In one study, patients using a lotion containing 1% coal tar had better results than the patients using a product that contained 5% coal tar extract. Other studies have found similar results. For this reason, it’s best to ask your dermatologist for a product recommendation.

Coal tar warning

Never apply coal tar to your genitals or rectum unless your dermatologist recommends doing so.

Does coal tar cause cancer?

In California, you’ll find cancer warnings on some coal tar products you can use to treat psoriasis. This warning was added to products in California due to: 

• Animal studies (where the animals were exposed to a lot more coal tar than we would use to treat psoriasis)

• Occupational studies (where a person works with industrial coal tar)

To date, studies fail to show an increased risk of cancer in people who use coal tar to treat psoriasis or atopic dermatitis (eczema). People who work with industrial coal tar, however, have an increased risk of developing cancer of the lungs, scrotum, and skin. 

How to use

You’ll find coal tar in many different products used to treat psoriasis. Coal tar can be an effective treatment for scalp psoriasis and is found in psoriasis shampoos. You’ll also find it in bath solutions, ointments, and many other forms.

Coal tar shampoo

When using a coal tar shampoo to treat scalp psoriasis, make sure that the shampoo gets on your scalp.

Coal tar can also be applied to the skin with psoriasis. When treating the skin, you massage the coal tar into the psoriasis. Your dermatologist will tell you how often to do this.

To increase the effectiveness of coal tar, your dermatologist may have you wrap the treated area.

Only do this when your dermatologist recommends it. Wrapping greatly increases the strength of coal tar.

Possible side effects

While coal tar has an excellent safety record, it can:

• Irritate the skin

• Cause a rash or acne-like breakout

• Lead to easily burned skin from the sun or a tanning bed because it makes your skin more sensitive to ultraviolet (UV) light

• Stain skin, light-colored hair, and clothing

• Leave an unpleasant odor

• Make hair dry and brittle when used to treat scalp psoriasis

• Worsen psoriasis

Immediately stop using coal tar if you develop:

• Severe stinging or burning

• Swelling

• Worsening psoriasis

What to discuss with your dermatologist

It’s important to tell your dermatologist if you:

• Have irritated skin or any other side effect

• Stop using coal tar

• Develop worsening psoriasis

Images
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Resources
Cordoro KM. “Management of childhood psoriasis.” Adv Dermatol. 2008;24:125-69.

Feldman SR. “Treatment of psoriasis.” UpToDate 2015 Jul, Wolters Kluwer Health. Last accessed November 2015.

Menter A, Korman NJ, et al. “Guidelines of care for the management of psoriasis and psoriatic arthritis. Section 3. Guidelines of care for the management and treatment of psoriasis with topical therapies.” J Am Acad Dermatol 2009;60:643-59.

Paghdal KV, Schwartz RA. “Topical tar: Back to the future.” J Am Acad Dermatol. 2009 Aug;61(2):294-302.