There are lots of myths about what causes acne. You may be surprised to know that acne isn't caused by having a poor diet (such as eating lots of chocolate) or bad hygiene. In fact, washing too much can make it worse. It’s also not likely to be caused by stress.

During puberty, both men and women produce more of the male hormone testosterone. This increases the production of sebum in your skin, causing it to become greasy and encouraging spots. It's thought that this is one of the main reasons most teenagers develop acne during puberty. But if you have acne, it doesn't always mean that you have high levels of testosterone. Instead, your body may be more sensitive to the effects of testosterone.

If you're a woman, hormonal changes just before your period may trigger acne. Newborn babies can sometimes get acne in the first few months of life.

If you miss a dose of tretinoin cream, skip the missed dose and go back to your regular dosing schedule.
Do not use 2 doses at once.

There’s a chance that acne can run in families. For example, if both your parents had acne you have an increased chance of having it too.

Other causes of acne may include:

• oily cosmetic products
• medicines, such as anabolic steroids, steroid creams and ointments, and lithium

Acne usually clears up as you get older. If you have more severe acne, you might get scarring. This can be permanent but usually improves over a long time.

• Scarring. Up to one in five people with acne have noticeable scarring. If you pick and squeeze your spots, you increase the chance of developing scars. Scars can be narrow ‘ice pick’ scars or broader ‘pock marks’. These are firstly purple in colour before fading to a whitish colour. Rarely, ‘keloid’ (firmer lumpy) scars may develop on your skin.
• Hyperpigmentation (your skin becomes darker in the areas affected by acne). This is usually only noticeable if you have a dark skin tone.
• Psychological problems. Acne may have a psychological effect on you, for example making you feel depressed or anxious. It can also affect your self-confidence, for example if people comment on your acne. Talk to your GP if your acne is making you start to feel low.