Practical information on using tetracyclines

Tetracyclines have a broad spectrum of activity, which includes activity against gram-positive and gram-negative bacteria, Chlamydia species, Rickettsia species, Mycoplasma species, spirochaetes, some nontuberculous mycobacteria and some protozoa (eg Plasmodium species causing malaria).

Doxycycline is the preferred tetracycline in most situations. Short courses (up to 10 days) of doxycycline have not been associated with tooth discolouration, enamel hypoplasia or bone deposition, even in childrenBoast, 2016Cross, 2016Gaillard, 2017Hemphill, 2019Melloni, 2017Poyhonen, 2017Stultz, 2019Thompson, 2019Todd, 2015. However, use in children is limited by the lack of a suitable commercially available formulation (eg an oral liquid formulation).

Minocycline is active against some bacteria that are resistant to other tetracyclines, including strains of staphylococci. However, adverse effects limit its use (eg benign intracranial hypertension, vestibular adverse effects, skin pigmentation).

Oesophagitis can occur with oral doxycycline and, less commonly, oral minocycline. Oral tetracyclines should be taken with food and a large glass of water, and the patient should be instructed to remain upright after administration. Photosensitivity reactions can occur with tetracyclines; warn patients to avoid sun exposure.

Tetracyclines have many clinically significant drug interactions. Consult an appropriate resource on drug interactions if starting or stopping these drugs in patients taking other drugs.