If you’re dealing with a flaky, itchy scalp that won’t quit, coal tar shampoo is one of the most effective over-the-counter options you haven’t tried yet. It’s a medicated treatment that’s been used for decades, and it works differently than regular dandruff shampoos. You apply it to wet hair, work it into the scalp, leave it on for several minutes, and rinse. The results can last for days, not just hours.
It’s not a cure for chronic conditions, but it controls symptoms well enough that many people use it as their go-to maintenance treatment.
How Coal Tar Shampoo Works
Coal tar slows the rapid overproduction of skin cells that causes the thick, flaky buildup you see with psoriasis and seborrheic dermatitis.
Think of it this way: a normal scalp sheds skin cells gradually. On a scalp with psoriasis or seborrheic dermatitis, those cells reproduce too quickly and pile up into visible flakes. Coal tar puts the brakes on that cycle, so the buildup never gets a chance to form.
What Conditions Does It Treat?
Coal tar shampoo is labeled and approved for three main conditions: dandruff, seborrheic dermatitis, and psoriasis. These three scalp problems share a common thread — they all involve inflammation and abnormal skin-cell turnover.
The table below shows the differences between these conditions and what coal tar does for each.
| Condition | Symptoms | Coal Tar’s Role |
|---|---|---|
| Dandruff | White or yellow flakes, mild itching | Reduces flaking and itch |
| Seborrheic dermatitis | Greasy, yellowish scales; redness; stubborn itch | Slows skin-cell turnover, calms inflammation |
| Scalp psoriasis | Thick, silvery scales; patches of red skin; itching | Breaks down scale, slows rapid cell growth |
Some sources also mention coal tar for eczema and other scaly, itchy skin conditions, but those uses aren’t always on the label and may be off-label depending on the product. If you’re using it for something other than the three main conditions, check with a dermatologist first.
How Often Should You Use It?
Usage instructions vary by brand, so follow the specific label on your product. Mayo Clinic’s directions for coal tar shampoo state: adults should use it once a day to once a week, or as directed by a doctor. Drugs.com’s professional monograph says coal tar shampoos are usually used twice weekly.
A common clinical recommendation is to use it 2–3 times per week, leaving it on for at least 10 minutes before rinsing.
Here’s the general routine that works for most people:
- Wet your hair and scalp thoroughly
- Massage the shampoo vigorously into your scalp
- Leave it on for 5–10 minutes (check your label)
- Rinse thoroughly, then repeat the application
- Finish with conditioner if needed to offset dryness
Safety, Side Effects, and What to Know Before You Buy
Coal tar is meant for external use only on the scalp and skin. Don’t use it on broken or inflamed skin, around your eyes, or in the genital area. Skin irritation is the most commonly reported side effect, and the risk depends on the product’s concentration.
Two practical things people don’t expect: coal tar has a strong, distinctive odor, and it can stain hair, skin, and fabrics. It’s a trade-off you accept for the symptom relief. If the smell bothers you, rinse thoroughly and follow with a regular conditioner.
Because coal tar comes in many products at different concentrations — from 0.5% up to 5% and higher — directions vary widely by brand. Don’t assume one product’s instructions apply to all of them. Always read the label on the bottle you bought.
For psoriasis, the AAD notes coal tar is one option among several, especially useful for scalp psoriasis and controlling itch and scale rather than as a permanent cure. If you’re ready to try it, our roundup of the best coal tar shampoos compares top-rated formulas to help you pick one that fits your routine.
References & Sources
- Cleveland Clinic. “Coal Tar Shampoo.” Overview of uses, mechanism, and application for scalp conditions.
- Mayo Clinic. “Coal Tar (Topical Route) Description and Brand Names.” Provides adult dosing directions for the shampoo dosage form.
- DailyMed (NIH). “Therapeutic Coal Tar Shampoo Label.” Official FDA labeling listing approved uses for dandruff, seborrheic dermatitis, and psoriasis.