Do diphenhydramine (Benadryl) and prednisone pass through breast milk?

From the Guidelines

Both diphenhydramine and prednisone can pass into breast milk, but the extent of passage and safety for breastfeeding infants differ between the two medications. Diphenhydramine transfers into breast milk in small amounts and may cause drowsiness or irritability in nursing infants, and it can also potentially reduce milk supply in some women 1. If an antihistamine is needed while breastfeeding, newer non-sedating options like loratadine or cetirizine are generally preferred. Prednisone also passes into breast milk but in very small amounts, typically less than 0.1% of the maternal dose, as noted in studies on corticosteroids and breastfeeding 1. For mothers requiring prednisone, breastfeeding is usually considered safe, especially at doses below 20 mg daily, with recommendations to delay breastfeeding or discard breast milk accumulated in the 4 hours following glucocorticoid administration for doses of prednisone ≥20 mg a day (or equivalent) 1. To minimize infant exposure to either medication, consider taking the medication immediately after nursing and waiting 3-4 hours before the next feeding when possible. For short-term, necessary use of either medication, the benefits often outweigh the minimal risks to the breastfed infant, but always consult with your healthcare provider for personalized advice based on your specific situation and medication dosage. Some key points to consider include:

• The safety of diphenhydramine and prednisone during breastfeeding
• The potential effects of these medications on the breastfed infant
• Alternative medications that may be safer for breastfeeding mothers
• The importance of consulting with a healthcare provider before taking any medication while breastfeeding. Given the information from the most recent and highest quality studies 1, prednisone at doses less than 20 mg daily is considered compatible with breastfeeding, but caution is advised with higher doses or with the use of diphenhydramine.

From the Research

Drug Passage into Breast Milk

• Drugs ingested by a lactating mother can appear in human milk to some extent and be ingested by a breast-feeding infant, as they pass from maternal plasma into milk by passive diffusion 2.
• The distribution of drugs into milk is affected by physiochemical characteristics, such as acid-base characteristics, relative protein binding in plasma and milk, and lipid solubility, as well as milk composition 2.

Diphenhydramine and Breast Milk

• A study developed a method for the simultaneous determination of 11 antihistamines, including diphenhydramine, in breast milk by gas chromatography-mass spectrometry, indicating that diphenhydramine can be detected in breast milk 3.
• Antihistamines, such as diphenhydramine, are excreted into breast milk in small amounts, but there is limited data on their effects on newborns and safety during breastfeeding 3.

Prednisone and Breast Milk

• Prednisone can be taken by nursing mothers, but when used at doses higher than 20 mg/day, an interval of 4 hours after dosing and prior to breastfeeding is recommended 4.
• Prednisone is considered compatible with nursing, but caution is advised when used at high doses 4.

General Considerations

• The relative infant dose (RID) is a relevant indicator of infant exposure to a drug, and most drugs show RID values of <10%, indicating that drug concentrations in infant serum do not reach a level known to be therapeutic in adults unless drug clearance is markedly lower than the adult level on a weight basis 5.
• The milk-to-plasma concentration ratio and maternal drug clearance should be considered when interpreting the distribution of drugs into breast milk 5.