There is no evidence that mebendazole, even at high doses, is effective for hydatid disease. There have
been rare reports of neutropenia and agranulocytosis when mebendazole was taken for prolonged
periods and at dosages substantially above those recommended.
Periodic assessment of organ system functions , including hematopoietic and hepatic, is advisable
during prolonged therapy.
Information For Patient
Patients should be informed of the potential risk to the fetus in women taking mebendazole during
pregnancy, especially during the first trimester (See Pregnancy).
Patients should also be informed that cleanliness is important to prevent reinfection and transmission of
Carcinogenesis, Mutagenesis, Impairment Of Fertility
In carcinogenicity tests of mebendazole in mice and rats, no carcinogenic effects were seen at doses as
high as 40 mg/kg (one to two times the human dose, based on mg/m2 ) given daily over two years.
Dominant lethal mutation tests in mice showed no mutagenicity at single doses as high as 640 mg/kg (18
times the human dose, based on mg/m2 ). Neither the spermatocyte test, the F1 translocation test, nor the
Ames test indicated mutagenic properties. Doses up to 40 mg/kg in mice (equal to the human dose,
based on mg/m2 ), given to males for 60 days and to females for 14 days prior to gestation, had no effect
upon fetuses and offspring, though there was slight maternal toxicity.
Pregnancy Category C
Mebendazole has shown embryotoxic and teratogenic activity in pregnant rats at single oral doses as
low as 10 mg/kg (approximately equal to the human dose, based on mg/m2 ). In view of these findings the
use of mebendazole is not recommended in pregnant women. Although there are no adequate and wellcontrolled
studies in pregnant women, a post-marketing survey has been done of a limited number of
women who inadvertently had consumed mebendazole during the first trimester of pregnancy. The
incidence of spontaneous abortion and malformation did not exceed that in the general population. In 170
deliveries on term, no teratogenic risk of mebendazole was identified.
It is not known whether mebendazole is excreted in human milk. Because many drugs are excreted in
human milk, caution should be exercised when mebendazole is administered to a nursing woman.
The drug has not been extensively studied in children under two years; therefore, in the treatment of
children under two years the relative benefit/risk should be considered.