Coal Tar Shampoo: Where It Still Fits, and the Smell Problem
The oldest active on the shelf, still legal
Coal tar shampoo is the oldest dandruff treatment still sold over the counter, and the label is the place to start. The DailyMed labels for coal tar shampoo list the active ingredient as solubilized coal tar extract at 2.5 percent, which is coal tar at 0.5 percent, and the purpose as anti-dandruff, anti-seborrheic dermatitis, and anti-psoriasis. The marketing category is OTC Monograph Drug M032, which is the FDA monograph that lets these shampoos be sold without a prescription. The use line on the label is narrow and honest: it controls the symptoms of dandruff, seborrheic dermatitis, and psoriasis. It does not claim to cure any of them.
The mechanism is different from the other actives in the aisle, and that is why it still has a place. Ketoconazole and selenium sulfide are antifungals aimed at the Malassezia yeast behind dandruff. Coal tar is a keratolytic and anti-proliferative: it slows the rate at which skin cells grow and shed, which is the process that makes the scale in the first place. For psoriasis plaques on the scalp, where the problem is overproduction of skin cells rather than yeast, that mechanism is the right tool. For ordinary dandruff, it is one option among several, and usually not the first.
Where it fits, and where it does not
The fit is psoriasis first. A scalp with thick, silvery plaques that do not respond to antifungal shampoos is the coal tar case, and the dermatology guidance puts it there: a keratolytic that slows cell turnover, used two to three times a week, left on for the contact time on the label, usually several minutes. Seborrheic dermatitis is the second case, where the slowing effect helps with the scale even though the yeast is still part of the picture. Ordinary dandruff is the weakest case, because ketoconazole and selenium sulfide target the yeast directly and do it without the smell.
The smell is not a footnote. It is the reason people quit, and a post that does not say so is not being honest. Coal tar smells like creosote and asphalt, and the smell lingers in hair, on pillowcases, and in the bathroom. It can also stain light hair and light-colored towels, and it increases sun sensitivity on the scalp, which matters for anyone with thinning hair or a shaved head. Those are the costs, and the reader gets to decide whether the benefit is worth them. A shampoo that works and smells awful is a different product from a shampoo that works, and the review that says so is the useful one.
How to use it without hating it
The usage rules are the same as the other medicated shampoos, with one addition. Wet the hair, apply the shampoo to the scalp rather than the lengths, massage it in, and leave it on for the contact time on the label before rinsing. Follow with a regular shampoo if the smell bothers you, and condition the lengths, because coal tar is drying. Do not use it on broken or infected skin, and do not use it more often than the label directs, because more frequent use does not speed the result and does increase the irritation.
The honest place for coal tar in a rotation is as the second-line option: the shampoo you reach for when the antifungal has not moved the plaques, or the one you alternate with ketoconazole when the scale is thick and slow to lift. It has survived on the shelf since before most of the other actives were invented, which is a kind of evidence in itself. It has also survived with the same smell, which is why it is second-line and not first. Both facts belong in the same paragraph.
Related reading
If this topic is useful, these earlier guides go deeper on connected questions: Selenium Sulfide: The Dandruff Active That Also Slows the Skin Down, Scalp Psoriasis vs Dandruff: The Plaque Test, and Ketoconazole Shampoo: Twice a Week, Five Minutes, and the Strength Is Not the Point.
Frequently asked questions
What is coal tar shampoo used for?
It controls the symptoms of dandruff, seborrheic dermatitis, and psoriasis. It is sold under OTC monograph M032 at 0.5 percent coal tar.
How does coal tar work on the scalp?
It slows the rate at which skin cells grow and shed, which reduces scale. That is different from antifungal shampoos, which target the yeast behind dandruff.
Why does coal tar shampoo smell so bad?
Coal tar is derived from coal, and the smell is inherent to the ingredient. It lingers in hair and on pillowcases, and it can stain light hair.
Is coal tar shampoo safe to use every day?
No. Use it two to three times a week as directed on the label, leave it on for the stated contact time, and do not use it on broken or infected skin.