The commonest form, Acne vulgaris, typically begins in adolescence, although onset in the twenties or thirties is common, and it can range from the occasional flare-up of pimples or spots that do not require any treatments to severe cases that can cause scarring and psychological problems.
If one looks very closely at the facial skin of teenagers, up to 90% have some form of blackheads or mild spots.
Moderately severe acne, i.e. with lots of inflamed spots on the face and upper trunk, affect around 5% of teenagers.
Acne usually starts around the age of 12 to 13 in girls and slightly later in boys.
There is some evidence to suggest that acne is more common amongst some families, suggesting that genetic factors are important.
Occasionally acne affects babies (so called infantile acne), and chemical or drug induced acne can affect anyone. Certain cosmetics, or oral and topical steroids can also result in an outbreak of acne.
For more information about different types of acne, please visit Acnenet.