Spots don’t stop just because you’ve passed adolescence. About half of women and a quarter of men get acne at some stage in their adult lives, and I’d say that at least 20 per cent of the women I see in my clinic want treatments for spots. The number seems to be growing, perhaps because we’re living more stressed lives. Stress alters our hormonal balance, raising levels of androgens, which can give rise to acne. Women tend to get flare-ups after exams.

Women are particularly prone to adult spots, and the reason isn’t dirty skin; it may just be a genetic predisposition. Hormonal changes that might cause spots include pregnancy, starting or stopping the contraceptive pill, certain medications, illness or menstrual problems.

Other triggers are milk chocolate (but not plain, which is good for the skin because it contains antioxidants), and using skin creams that are too heavy and block up the skin’s oil-secreting ducts. Thick sunscreens are a common problem. Another under-recognised cause is polycystic ovarian syndrome — which can cause higher levels of androgen hormones, and spots as a result. And never squeeze a spot. This releases the bacteria within, and can cause other spots and scarring.

To stop spots, use a non-alcohol-based, oil-reducing cleanser, such as Clinique Acne Solutions Cleanser or Dr Nick Lowe Sebum Control Cleanser, which clean pores without stripping the skin of moisture. But these will bring, say, only a 25 per cent improvement, so you may need antibacterial spot gels to control the acne bacteria that grow in blocked pores. Good ones contain substances that control the acne bacteria and reduce inflammation — try Clinique Spot Treatment Gel.

If none work, you may need to go to a doctor or dermatologist for a prescription antibiotic cream. The next step might be taking oral antibiotics, or going on to some types of birth control pill, which can be very effective in preventing acne.

Dr Nick Lowe is a leading dermatologist in London and Los Angeles

www.drnicklowe.com/acne.html