If you have psoriasis, there are many over-the-counter (OTC) topical treatments you can use to find relief. They come in many different options, like lotions, foams, bath solutions, and shampoos. One common ingredient is coal tar. This might seem strange, but it’s actually been used for over a century to treat psoriasis. It’s even been approved by the U.S. Food and Drug Administration (FDA) just for this purpose.
How Does Coal Tar Treat Psoriasis?
Coal tar comes from coal. It’s often used to make coal-tar pitch, which is used as a base for coatings and paint and in roofing and paving. But it can also be used to treat certain inflammatory skin conditions, such as eczema, psoriasis, and dandruff.
When you have psoriasis, your skin cells turn over rapidly, which causes red, itchy, scaly patches. Coal tar helps slow these cells’ rapid growth to restore your skin’s smooth appearance. It can also help relieve the inflammation and itching that occurs with psoriasis. Coal tar is most effective in treating:
- Plaque-type psoriasis (the most common type of psoriasis)
- Scalp psoriasis (especially if itching is the main symptom)
- Psoriasis on the palms of your hands and soles of your feet. This type of psoriasis is normally very hard to treat.
Your dermatologist may recommend that you try coal tar alone, or that you use it with a combination of other medications like topical corticosteroids, phototherapy, or both.
Coal tar should also not be confused with pine tar, which comes from pine wood. While it’s also used to treat skin conditions, most dermatologists recommend coal tar instead to treat psoriasis.
How Well Does Coal Tar Work?
Coal tar can work well to treat psoriasis, especially if it’s used in combination with other treatments. Some people see their psoriasis go away completely. Others go into remission, which means they go for a while without a flare-up of their psoriasis.
No single coal tar product is best for psoriasis. You can’t just assume that the higher its tar concentration, the better it is. In fact, studies have found that lotions containing just 1 percent of coal tar were more effective than those that contained 5 percent coal tar. It’s a good idea to ask your dermatologist to recommend a product.
Is It Safe to Use Coal Tar for Psoriasis?
Yes. Coal tar has been linked to skin, lung, bladder, kidney, and GI cancer. However, this was in either animal studies, where the animals were exposed to very high levels of coal tar, and in occupational studies, where people work with industrial coal tar. There’s no research to suggest that people who use coal tar to treat their psoriasis are at a greater risk for cancer.
California requires OTC coal tar products that contain more than 0.5% coal tar to be labeled with cancer warnings. However, the FDA says that OTC products with coal tar concentrations between 0.5% and 5% are safe, and there’s no evidence it causes cancer.
You should avoid coal tar if:
- You're pregnant or breastfeeding.
- You're sensitive to UV light or take drugs that make you more sensitive to UV light.
How Do You Use Coal Tar for Psoriasis?
You should always test a tar product on a small area of your skin or scalp first. If it turns red, use a moisturizer first – choose a heavy cream or ointments to lock water into your skin – before you apply it.
If you have scalp psoriasis, your doctor may recommend that you use coal tar shampoo. It’s very important to make sure the shampoo gets on your scalp. Leave it in place for 5 to 10 minutes before you rinse it out.
It can also be applied as a lotion or ointment. You massage the coal tar into the psoriasis once or twice a day. You can use an OTC product, but your doctor can also prescribe a compounded or specially made cream that also contains a corticosteroid. A commonly used one is 2% or 3% crude coal tar in triamcinolone cream 0.1% applied twice daily to individual spots of psoriasis. You can apply it to most areas where you have psoriasis, although you shouldn’t apply it to very sensitive areas like your genitals or buttocks unless your doctor tells you it’s OK to do so.
Sometimes, your doctor may also have you wrap the spots where you have psoriasis after you apply coal tar to them. This increases the product’s effectiveness. Don’t do it unless your doctor tells you to, since it makes the product much stronger.
Since coal tar can stain your hair, skin, and clothes, it’s best to use them at night and wear old clothes, like pajamas.
Are There Side Effects of Using Coal Tar?
Like any product, coal tar can have side effects. These include:
- Skin irritation
- Rashes or pimple breakouts
- Stained hair, skin, and clothing
- A bad odor
- Dry and brittle hair (if you use it as a shampoo)
It’s also very important to wear sunscreen when you use coal tar, especially if you spend a lot of time outdoors. The product makes your skin more sensitive to UV light, so you are more likely to get sunburned.
You should stop using coal tar and call your doctor if you notice:
- Your skin stings or burns.
- Your skin swells.
- Your psoriasis gets worse.