• Advise the person to stop treatment and seek medical advice if they develop severe headache and/or visual disturbances. This may be an early symptom of benign intracranial hypertension, a rare but serious adverse effect of tetracycline-like drugs.
• Inform the person that most adverse effects are not serious:
• Gastrointestinal disturbances are the most common:
• Nausea, vomiting, and diarrhoea are the most common symptoms.
• Tetracycline and oxytetracycline should be taken on an empty stomach, which may increase nausea (in particular, milk or antacids should be avoided). Doxycycline and lymecycline may be taken with food, which may help the person tolerate the drug.
• Tetracyclines can cause severe oesophagitis, presenting as a burning pain in the in the lower chest. To counteract this, recommend taking tetracyclines in an upright position with plenty of water, without chewing or breaking the tablets or capsules.
• Indigestion remedies, such as antacids (or medicines containing iron or zinc), should not be taken within 2–3 hours of tetracyclines.
• Advise women that:
• Yeast infections, such as vulvovaginal candidiasis, may occur initially as a result of the broad-spectrum nature of tetracyclines, but this should be minimal owing to the low doses used and extended course.
• Treatment of blepharitis with tetracyclines is rarely necessary in a woman of childbearing age. However, if the woman is taking the combined oral contraceptive pill, advise her that treatment may decrease the effectiveness of the contraceptive. For more information, see Antibiotics in the CKS topic on Contraception.
• Advise people to avoid excessive exposure to sunlight and sunbeds, especially if they are taking doxycycline.

[ABPI Medicines Compendium, 2006a; ABPI Medicines Compendium, 2006b; BNF 54, 2007]