Morphine
Relative Infant Dose (RID)
3%
✓ Verified
Milk-to-Plasma Ratio (M:P)
2.35
✓ Verified
What This Means
Morphine transfers about 3% of the maternal dose through breast milk. This is generally considered acceptable, but discussing timing of doses with your healthcare provider may be helpful. The M:P ratio of 2.35 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.
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: LactMed NBK501237 (Feb 2026): Range 3-9% RID across multiple studies. Oral 40mg/day → 3% RID (Feilberg et al. 1989); IV PCA → 5-9% RID (Gerdin et al. 1990). Lower end reflects typical oral dosing. • LactCheck by Benevolence Labs