Is Promethazine (Phenergan) DM safe to use while breastfeeding?

Promethazine DM and Breastfeeding

Promethazine should be used with significant caution during breastfeeding, and alternative medications are strongly preferred due to insufficient safety data and the FDA's explicit warning about unknown excretion into breast milk.

FDA Label Warning

The FDA label for promethazine explicitly states: "It is not known whether promethazine HCl is excreted in human milk. Because many drugs are excreted in human milk and because of the potential for serious adverse reactions in nursing infants from promethazine hydrochloride tablets, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother." 1

Limited Safety Evidence

• A 2022 systematic review on antihistamines during breastfeeding identified only one study examining promethazine, which investigated its impact on prolactin levels rather than infant safety or milk transfer 2
• The relative infant dose and actual transfer of promethazine into breast milk remain unknown, unlike other antihistamines where this has been quantified 2
• No studies have measured promethazine levels in breast milk or documented adverse effects in breastfed infants 2

Safer Alternative Antihistamines

If antihistamine therapy is necessary, consider these better-studied alternatives:

• Cetirizine has a relative infant dose of only 0.9% and documented safety data 2
• Loratadine has a relative infant dose of 0.8% with established safety profiles 2
• These second-generation antihistamines have quantified breast milk transfer below the 5% safety threshold 2

Safer Alternative Anti-emetics (if used for nausea)

If promethazine is being considered for anti-emetic purposes rather than antihistamine effects:

• Ondansetron is recommended as safe by the Association of Anaesthetists, with no waiting period required and no pumping-and-dumping needed 3
• Metoclopramide is listed as compatible with breastfeeding in anesthesia guidelines 4

Clinical Decision Algorithm

1. Determine the indication: Is promethazine needed for allergies, nausea, or sedation? 5
2. Choose safer alternatives first: Use cetirizine or loratadine for allergies; ondansetron for nausea 4, 3, 2
3. If promethazine is deemed essential: Discuss with the mother the lack of safety data and consider temporary cessation of breastfeeding during treatment 1
4. Monitor the infant closely for sedation, poor feeding, or respiratory depression if breastfeeding continues 5

Critical Caveats

• The sedating properties of first-generation antihistamines like promethazine pose theoretical risks of infant sedation and impaired maternal responsiveness during co-sleeping 4
• Most antihistamine product labels in both the EU and US recommend avoiding use during breastfeeding due to insufficient evidence 2
• The general principle that "most medications are safe during breastfeeding" does not apply when specific safety data are absent, particularly for sedating medications 6, 7