Drug Levels and Effects:

Summary of Use during Lactation:

Limited information indicates that levels of naproxen in breastmilk are low and adverse effects in breastfed infants are apparently uncommon. However, because of naproxen's long half-life and reported serious adverse reaction in a breastfed neonate, other agents may be preferred while nursing a newborn or preterm infant.

Drug Levels:

Maternal Levels.

Peak milk naproxen levels in a 5-month postpartum patient were 1.1 to 1.3 mg/L while taking oral naproxen 250 mg twice daily and 2.4 mg/L with a dose of 375 mg twice daily. Peak milk levels occurred 4 to 5 hours after the dose and fell slowly over 12 to 24 hours. From urinary excretion data the authors estimated that the infant received 0.26% of the mother's total dose or 1.9% of the maternal weight-adjusted dosage.[1] Using the peak milk level data, the estimated maximum intake of an exclusively breastfed infant would be 2.2 to 2.8% of the maternal weight-adjusted dosage, not including the contribution of any glucuronide metabolite.

Infant Levels.

Relevant published information was not found as of the revision date.

Effects in Breastfed Infants:

Naproxen possibly caused prolonged bleeding time, thrombocytopenia and acute anemia in one 7-day-old infant in a mother also taking bacampicillin.[2]

In one telephone follow-up study of 20 infants exposed to naproxen during breastfeeding, 2 mothers reported drowsiness and 1 reported vomiting in their infants. None of the reactions requiredmedicalattention.[3]

Possible Effects on Lactation:

A randomized study compared naproxen and tramadol for post-cesarean section pain. Patients received the drugs either on a fixed schedule or as needed. No difference in breastfeeding rates were seen among the groups.[5]

Alternate Drugs to Consider:



1. Jamali F, Tam YK, Stevens RD. Naproxen excretion in breast milk and its uptake by suckling infant. Drug Intell Clin Pharm. 1982;16:475. Abstract. PMID:6653409
2. Jamali F, Stevens DR. Naproxen excretion in milk and its uptake by the infant. Drug Intell Clin Pharm. 1983;17:910-1. Letter. PMID:6653409
3. Fidalgo I, Correa R, Gomez Carrasco JA et al. [Acute anemia, rectorrhagia and hematuria caused by ingestion of naproxen]. An Esp Pediatr. 1989;30:317-9. PMID:2787136
4. Ito S, Blajchman A, Stephenson M et al. Prospective follow-up of adverse reactions in breast-fed infants exposed to maternal medication. Am J Obstet Gynecol. 1993;168:1393-9. PMID:8498418
5. Sammour RN, Ohel G, Cohen M, Gonen R. Oral naproxen versus oral tramadol for analgesia after cesarean delivery. Int J Gynaecol Obstet. 2011;113:144-7. PMID:21435642

Substance Identification:

Substance Name:


CAS Registry Number:


Drug Class:

  • Analgesic Agents

  • Nonsteroidal Antiinflammatory Agents

  • Administrative Information:

    LactMed Record Number:


    Last Revision Date:

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