Acetaminophen
Lower relative transfer — not a safety determination. Always consult your healthcare provider.
Relative Infant Dose (RID)
2%
✓ Verified
Milk-to-Plasma Ratio (M:P)
1.17
✓ Verified
Evidence Sources
RID Source
Notarianni LJ, Oldham HG, Bennett PN. Passage of paracetamol into breast milk and its subsequent metabolism by the neonate. Br J Clin Pharmacol. 1987;24(1):63-67.
Notarianni et al. 1987 - Estimated maximum infant dose 1.85% of the weight-adjusted maternal oral dose; LactCheck displays 2.0% as rounded clinical value.
What This Means
Acetaminophen transfers about 2% of the maternal dose through breast milk. This may be acceptable in many cases, but individual factors — such as infant age, dose, and other medications — are important. Discuss timing of doses with your healthcare provider. The M:P ratio of 1.17 means the drug concentrates more in breast milk than in blood, meaning more may reach your baby. Consider discussing timing (e.g., taking after a feeding) with your healthcare provider.
Note: This drug has an M:P ratio above 1, meaning it may accumulate in breast milk with repeated dosing. Discuss accumulation effects with your healthcare provider, especially for long-term use.
Important: This information is for educational purposes only. Always consult your healthcare provider before taking any medication while breastfeeding. Do not stop prescribed medications without medical advice.
Data source: Verified clinical data • LactCheck by Benevolence Labs