to the editor: I enjoyed the excellent article on conjunctivitis written by Drs. Morrow and Abbott.1 I found it to be practical and useful. I do feel, however, that one point in the article is in error.
They write that systemic tetracyclines are contraindicated in women who are nursing. Tetracycline is excreted into breast milk in low concentrations. It binds to calcium in breast milk and is absorbed poorly by the infant. A study of lactating women who were taking 500 mg of tetracycline four times a day found that levels of tetracycline in the infants were below the level of detection (0.05 μg per mL).2,3 Theoretic concerns about the possibility of dental staining or delayed bone growth in the infants seems unlikely at these serum concentrations.3
In their publication “Transfer of Drugs and Other Chemicals into Human Milk,” the American Academy of Pediatrics places tetracycline under the label “Usually Compatible with Breast-Feeding,” the classification used for those medications that are safest in lactation.4
Better choices may be available for the treatment of meibomianitis or acne rosacea in lactating women, especially since these conditions often require prolonged treatment, but I feel it is unwise to perpetuate the misconception that tetracyclines are always contraindicated during lactation.
editor's note: This letter was sent to the authors of “Conjunctivitis,” who declined to reply.