Some cosmetics, particularly those from the U.S. and the ethnic Indian make-ups, may induce blackhead formation in the skin.

Certain hair oils or pomades, particularly those used to " defrizz " very curly hair, may induce blackheads and whiteheads along the hair margin.

These should be avoided by those with a tendency toward developing acne.

In the same way, some people react to suntan oils with a worsening of acne. Always test suntan oils on a small area of the chest first to make sure you do not react to them.