Coal Tar
Explained
Coal Tar isn't a cosmetic ingredient anywhere: it's a medicine. You can grab it off the shelf in the US and you'll need a prescription in the EU.
The FDA allows it at 0.5% to 5% for dandruff, seborrheic dermatitis, and psoriasis. States are also required to label the actual coal tar concentration when a solution or fraction is used as the source (so "5% Coal Tar Solution" is not the same as 5% coal tar).
Studies show it helps calm itch and inflammation, and slow down skin cells that are multiplying too fast.
A 2013 study showed it works by switching on the receptor that restores filaggrin (a key skin barrier protein) and repairs the barrier in eczema.
This ingredient is fungal acne safe; in another test, a coal tar gel inhibited the growth in 52/54 Malassezia furfur strains tested, and separate work found its fungus-slowing effect comparable to a ketoconazole gel.
The downsides are dose-related: tar folliculitis and acne-like bumps are common side-effects at concentrations above 2%. Plus, this ingredient is phototoxic, so sun exposure right after use can burn. True allergic contact dermatitis also happens but is uncommon.
On the cancer question: coal tar contains PAHs and occupational exposure is genuinely linked to cancer, but a cohort of 13,200 psoriasis and eczema patients found no increased risk of skin cancer or other cancers after topical treatment.
Fun fact: Coal tar is one of the oldest skin treatments still in regular use.
See all 6 products with Coal Tar
