Several hormones in the body control the menstrual cycle. The average cycle lasts about 28 days, and on each one of those days, hormone levels can change. The changes the body goes through in the first half of the cycle are predominantly controlled by estrogen, and the second half is influenced by progesterone.
If there are acne flares one to two weeks before menstruation, if they go away with the onset of a period, and if this pattern repeats at least twice in a row, it may be because of premenstrual acne.
During this time, the ratio of estrogen and progesterone changes, which can affect the occurrence of acne breakouts. The drop in these hormones a few days before a period may also trigger acne flare-ups.
Period acne is different than the typical acne that occurs during other weeks of the menstrual cycle. Breakouts of pimples from period acne are usually on the lower half of the face (chin, cheeks), jawline, and neck. They are usually red, inflamed, raised bumps (papules) that rarely develop into pustules (papules with pus). They can be very frustrating, but try to resist squeezing them. This can make them worse and take longer to go away.