Drug interactions, side effects and safety considerations

For full list of warnings, drug interactions & side effects please refer to drug-specific sections of the or .

Tetracyclines

(e.g. doxycycline, oxytetracycline, lymecycline)

• Avoid in pregnancy and in those under 12 years old - can cause permanent tooth discolouration and enamel hypoplasia
• Reduced absorption (up to 100%) with iron, calcium, magnesium and some nutritional supplements
• Photosensitivity may occur - advise patients to avoid exposure to sunlight/sun lamps

Quinolones

(e.g. ciprofloxacin, ofloxacin, levofloxacin) 

Note: MHRA safety advice

Patient information leaflet required on prescription

Key safety considerations are summarised in this NHS D&G Quinolone safety alert poster

• Higher risk of tendon injury in over 60 years old, renally impaired, solid-organ transplant
• High risk for serious drug interactions (see the BNF or seek pharmacy advice)
• Avoid in patients with a prolonged QTc interval
• Avoid prescribing in combination with corticosteroids
• Reduced absorption with iron, calcium, magnesium and some nutritional supplements
• Stop treatment at the first sign of side effects (tendonitis)

Metronidazole

• Alcohol must be avoided completely whilst taking metronidazole and for 48 hours after stopping treatment

Macrolides

(e.g clarithromycin, erythromycin, azithromycin)

• High risk for serious drug interactions (see the BNF or seek pharmacy advice)
• Avoid in patients with a prolonged QTc interval
• Avoid Clarithromycin and Erythromycin with statins (omit statin for duration of course)

Trimethoprim / Co-trimoxazole

Avoid concomitant use with Methotrexate - can cause severe (potentially fatal) bone marrow suppression

Cephalosporins

(e.g. cefalexin, cefaclor)

• See User Guide section on penicillin allergy and cross-sensitivity with other beta-lactam antibiotics