Summary of Use during Lactation

Mebendazole is poorly excreted into breastmilk and poorly absorbed orally. Reports on the use of mebendazole during breastfeeding have found no adverse reactions in breastfed infants. There are rare case reports of a decrease in milk supply following use of mebendazole, but no convincing evidence that these were caused by the drug. No special precautions are required.

Drug Levels

Maternal Levels. One author reported information received by personal communication from the manufacturer stating that after a single 100 mg oral dose of mebendazole to a nursing mother (time postpartum not stated), the peak milk level was 6 mcg/L. Mebendazole was no longer detectable (<1 mcg/L) in milk 13.25 hours after the dose.[1]

One woman was given mebendazole 100 mg orally twice daily for 3 days beginning the first day postpartum. Mebendazole was measured in milk following treatment (exact timing not stated). Mebendazole was undetectable (<20 mcg/L) in milk. The authors stated that this value was in agreement with those reported by the manufacturer and that the infant probably absorbed negligible mebendazole from breastmilk.[2]

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

Effects in Breastfed Infants

A case series reported 45 nursing mothers who took mebendazole in doses ranging from 100 mg once to 200 mg twice daily for 3 days. About half took 100 mg repeated once after 7 to 14 days. Thirty-three of the infants were exclusively breastfed with ages ranging from 1 to 30 weeks of age. Eight of the 12 partially breastfed infants were over 20 weeks of age. None of the infants were reported by their mothers to have had any adverse reactions.[3]

A cohort of 33 infants who were breastfed (extent not stated) by hospitalized mothers taking nifurtimox was followed in the Democratic Republic of the Congo. Thirty mothers took a full course of 30 doses of oral nifurtimox 15 mg/kg daily and all received 14 doses of intravenous eflornithine 400 mg/kg daily for 7 days for human African trypanosomiasis. (sleeping sickness). Seventeen nursing mothers also took mebendazole. No serious adverse events were reported in any of the breastfed infants.[4,5]

Effects on Lactation and Breastmilk

A nursing mother who was 13 weeks postpartum was taking oral metronidazole 250 mg three times daily. Milk production seemed to be unaffected. On the eighth day of therapy she passed a roundworm. Metronidazole was discontinued and oral mebendazole 100 mg twice daily was started. The patient was "tense" for a few days after passing the worm. On the second day of mebendazole treatment, milk production dropped markedly and she began supplementation with formula. By day 7, milk production had ceased. The authors suggested that mebendazole might have caused the drop in milk production, but offered no further evidence other than the temporal relationship.[6]

Four patients were treated with oral mebendazole 100 mg twice daily for 3 days beginning the first day postpartum. Two had pinworm (Enterobius), 1 had roundworm (Ascaris) and 1 had hookworm (Ancyclostomia) infestations. All breastfed successfully.[2]

One author reported information received by personal communication from the manufacturer stating that no inhibition of lactation was noted after a single 100 mg oral dose of mebendazole to a nursing mother (time postpartum not stated).[1]

In a case series reported 45 nursing mothers who took mebendazole in doses ranging from 100 mg once to 200 mg twice daily for 3 days, one mother reported a slight decrease in milk production.[3]

Alternate Drugs to Consider

Albendazole

References

1.

Stoukides C. Can a mother safely breastfeed while on mebendazole (Vermox)? J Hum Lact. 1994;10:269. [PubMed: 7619284]

2.

Kurzel RB, Toot PJ, Lambert LV, et al. Mebendazole and postpartum lactation. N Z Med J 1994;107:439. Letter. PMID: 7970347. [PubMed: 7970347]

3.

Karra N, Cohen R, Berlin M, et al. Safety of mebendazole use during lactation: A case series report. Drugs R D. 2016;16:251–4. [PMC free article: PMC5045833] [PubMed: 27623793]

4.

Schmid C, Kuemmerle A, Blum J, et al. In-hospital safety in field conditions of nifurtimox eflornithine combination therapy (NECT) for T. b. gambiense sleeping sickness. PLoS Negl Trop Dis. 2012;6:e1920. [PMC free article: PMC3510081] [PubMed: 23209861]

5.

Kuemmerle A, Schmid C, Kande V, et al. Prescription of concomitant medications in patients treated with nifurtimox eflornithine combination therapy (NECT) for T.b. gambiense second stage sleeping sickness in the Democratic Republic of the Congo. PLoS Negl Trop Dis. 2020;14:e0008028. [PMC free article: PMC7004379] [PubMed: 31986140]

6.

Rao TS. Does mebendazole inhibit lactation? N Z Med J 1983;96:589-90. Letter. PMID: 6575310. [PubMed: 6575310]

Substance Name

Mebendazole

CAS Registry Number

31431-39-7

Drug Class

Breast Feeding

Lactation

Anti-Infective Agents

Antiparasitic Agents

Antinematodal Agents