Things that can cause acne are stress, oily moisturizers and make up (watch out for lanolin, petrolatum, vegetable oils, butyl stearate, lauryl alcohol and oleic acid), pressure from headbands/chin straps and medications (such as steroids). The impact of diet on acne is controversial however for your general health you should have a healthy balanced diet with plenty of fruit and vegetables and at least 2L of water a day. The treatment of acne starts with simply avoiding triggers and good hygiene. Antibacterial facial washes and tea tree oil can be helpful-speak to your pharmacist. If this isn’t enough, see your GP or see a Dermatologist.