6.Sulphur

Typically found in volcanic areas, it works similarly to benzoyl peroxide and salicylic acid. Sulfur helps dry out the surface of your skin to help absorb excess oil (sebum) that may contribute to acne breakouts. It also dries out dead skin cells to help unclog your pores
Many products also combine sulfur with another ingredient like sulfacetamide to reduce inflammation.

Where can buy – It can be found as a prescription from your dermatologist or in some over-the-counter products.