Tetracyclines

This information on drug interactions with antimicrobials is intended for use as a guide and not as a complete reference source

Antibiotic Class	Interacting Drug	Comment
Tetracyclines e.g. Doxycycline Lymecycline Minocycline	Antacids, Zinc, Calcium, Magnesium, Aluminium, Sucralfate and Bismuth Preparations	Risk of reduced bioavailability and efficacy of tetracyclines. Separate the doses by 2 to 3 hours or more to avoid interaction.
	Iron	Iron to be given 3 hours before or 2-3 hours after the tetracyclines. The absorption of both the tetracyclines and iron compounds is greatly reduced by concurrent use.
	Warfarin	Risk of bleeding - monitor INR closely.
	Methotrexate	Tetracyclines can increase risk of methotrexate toxicity.
	Systemic retinoids. e.g. Oral isotretinoin	Concomitant use of retinoids and tetracyclines is contraindicated due to risk of causing benign intracranial hypertension.
	Antiepileptics	Doxycycline levels may be reduced. Monitor for efficacy and consider increase in doxycycline dose.
	Rifampicin	Doxycycline levels may be reduced. Monitor for efficacy and consider increase in doxycycline dose.
	Ciclosporin	Doxycycline is predicted to increase ciclosporin concentrations. Action: monitor (and dose adjust the ciclosporin as needed).
	Lithium	Tetracyclines might increase the risk of lithium toxicity when given with lithium. Action: monitor for lithium toxicity and adjust the dose as needed.
	Strontium	Suspend strontium ranelate treatment if tetracycline needed.
	Cyproterone	Monitor for pigmentation with minocycline.
	Combined oral contraceptive	Monitor for pigmentation with minocycline.