Spot of bother

"Adult acne is caused by the clogging up of pores by sebum, which is an oily substance that is produced by the skin's sebaceous [oil] glands," explains Dr Gavin Chan (right), a specialist in dermatology at SkinCentral. "Clogged pores are visible as blackheads and whiteheads, and, when inflamed, become red, unsightly bumps, pustules or cysts."

The causes of adult acne are broad and can include stress, hormonal changes and underlying medical conditions, such as polycystic ovarian syndrome, according to Chan. For mild cases, he suggests products containing salicylic acid, glycolic acid or prescription topical retinoid products.