A yellowish element that smells of rotten eggs and it might be familiar to you from the periodic table (has the symbol S in there). It has a long history of medicinal use thanks to its antifungal, antibacterial and keratolytic activity. It used to be a very common ingredient in the treatment of inflammation-related skin diseases such as acne, rosacea and seborrheic dermatitis, however, due to its malodorousness, it is less popular nowadays.
Sulfur's precise mechanism of action is not known, but we do know that its effectiveness depends on its direct interaction with the skin surface, meaning the smaller the particle size, the better the effect. The United States Pharmacopeia lists two types of sulfur, sublimed and precipitated. The latter one has a smaller particle size and counts as a superior version.
Sulfur is also a team-player and works well when combined with other anti-acne agents, such as salicylic acid or sodium sulfacetamide. In fact, the combination of 10% sodium sulfacetamide and 5% sulfur is the active ingredient duo of several Rx-only anti-acne products.
As for the disadvantages, there is the rotten egg smell. Also in higher concentrations, it might cause a mild burning sensation and dry skin. If you are new to sulfur, patch testing it first is a good idea.
Show me some proof
- Gupta, Aditya K., and K. Nicol. "The use of sulfur in dermatology." Journal of drugs in dermatology: JDD 3.4 (2004): 427.