What muscle relaxer is safe for a breastfeeding mother?

Safe Muscle Relaxants for Breastfeeding Mothers

Neuromuscular blockers such as suxamethonium, rocuronium, vecuronium, and atracurium are considered the safest muscle relaxants for breastfeeding mothers due to their poor lipid solubility, poor oral bioavailability, and minimal transfer into breast milk. 1

First-Line Options for Breastfeeding Mothers

• Neuromuscular blockers are unlikely to be present in breast milk in significant amounts as they are ionized at physiological pH and have poor oral absorption with rapid elimination from maternal circulation 2, 1
• Non-depolarizing neuromuscular blocking drugs (rocuronium, vecuronium, atracurium) are quaternary ammonium compounds with poor lipid solubility and poor oral bioavailability, making them safe choices for breastfeeding mothers 2, 1
• Breastfeeding can be resumed once the mother has recovered from neuromuscular block 2, 1

Reversal Agents

• Neostigmine is a quaternary ammonium compound with a half-life of 15–30 minutes, and the amount transferred to breast milk is probably too small to be harmful 2, 1
• Sugammadex is a large, highly polar molecule with likely very low amounts in milk and unlikely oral absorption by the infant 2, 1

Local Anesthetics as Alternatives

• Local anesthetics (lidocaine, bupivacaine) can be safely used in breastfeeding mothers with no need to interrupt breastfeeding 3, 4
• These amino amide compounds may be secreted in small amounts in breast milk but pose no significant risk to the infant 2

Cautions with Other Muscle Relaxants

• Cyclobenzaprine (oral muscle relaxant) should be used with caution as it is closely related to tricyclic antidepressants, some of which are excreted in human milk 5
• The FDA label for cyclobenzaprine states: "It is not known whether this drug is excreted in human milk. Because cyclobenzaprine is closely related to the tricyclic antidepressants, some of which are known to be excreted in human milk, caution should be exercised when cyclobenzaprine hydrochloride is administered to a nursing woman." 5

Safe Analgesics for Muscle Pain in Breastfeeding Mothers

• NSAIDs such as ibuprofen, diclofenac, and naproxen are considered safe and compatible with breastfeeding 1
• Paracetamol (acetaminophen) is safe as the amount an infant would ingest via breast milk is significantly less than pediatric therapeutic doses 1

Monitoring and Precautions

• Monitor infants for signs of sedation, respiratory depression, or poor feeding, especially when using medications with sedative properties 1, 6
• Most adverse drug reactions in breastfed infants occur in neonates and infants under 2 months of age; only 4% of adverse reactions occur in infants older than 6 months 6

Common Pitfalls to Avoid

• Avoid long-term use of benzodiazepines, especially diazepam, due to accumulation of active metabolites 1
• Don't assume all muscle relaxants have the same safety profile - always check specific drug properties and transfer into breast milk 1, 7
• Many mothers are inappropriately advised to discontinue breastfeeding or avoid taking essential medications because of fears of adverse effects on their infants, when only a small proportion of medications are actually contraindicated 8