Most people develop acne during adolescence. It is most prevalent in those aged 16 to 18 years. Acne usually becomes less of a problem after the age of 25 years, although about 15% of women and 5% of men continue to have acne as adults. Diet has little effect. Acne may cycle with the menses, and it may improve or worsen during pregnancy. Although cosmetics rarely aggravate acne, the traditional advice to avoid greasy preparations seems prudent.