What can I do to decrease acne during my period?

Vitamin b6. Vitamin b6 may be helpful, along with oral zinc in decreasing hormonal acne flares. This is addition to topical agents.
Gels/creams for acne. Acne occurs when skin glands produce more oil, but the openings of the glands are blocked by little plugs of dead skin cells (comedones). Skin oils leak sideways into the skin, causing inflammation that brings in lots of white blood cells, forming a pustule. Causes include hormonal changes, emotional stress, certain medicines, skin rubbing, etc... Medicines & birth control pills help control acne.