Is topical treatment with minoxidil compatible with pregnancy and breast-feeding?
A 31-year-old, 25 weeks' pregnant woman has been using Recrea (minoxidil) 20 mg/mL for alopecia since before conception. She is concerned about the possible effects on the child in utero and during future breast-feeding.
Minoxidil is a vasodilator originally used systemically for hypertension. Due to its tendency to cause hypertrichosis, it has also been administered topically in the treatment of alopecia. In both cases, doses of approximately 40 mg/d are recommended. However, while 90 percent of an oral antihypertensive dose is absorbed, the absorption of topically administered minoxidil measures a mere 0.3-4.5 percent. Hence, systemic drug exposure following topical administration should stay below five percent of that in oral treatment (1,2).
The safety of minoxidil in pregnancy has previously been investigated by the Drug Research and Information Centre (3). By then, four cases of fetal exposure to systemic minoxidil therapy had been reported in the literature. Two of the four children had severe malformations of different kinds. Two children (one with malformations) presented with hypertrichosis at birth. An updated Medline search identified two additional reports of minoxidil exposure during pregnancy. In these cases, the drug had been topically administered. One of the exposed children was severely malformed with a caudal regression syndrome and the other one was born with hypertrichosis (4-5).
In the Swedish Medical Birth Registry, there are five reports of topical minoxidil exposure during the first trimester of pregnancy (6). No malformations were noted in these children.
Milk levels of minoxidil are similar to those in plasma and the suckling infant's dose should be no higher than five percent of the weight adjusted maternal oral dose (7-8). Although the calculations are based on data from one single case, it has been suggested that breast-feeding should be safe in women taking minoxidil systemically (8).
Information about minoxidil use in pregnancy and lactation is scarce. There are reports of hypertrichosis in children exposed to minoxidil in utero (both oral and topical administration). Similarily, there are reports of severe malformations in exposed children, but the small number of observations makes it impossible to establish a causal relationship.
Breast-feeding is likely to be safe when the mother uses minoxidil locally, since it exposes the suckling infant only to exceedingly small doses of the substance. However, this conclusion is based on data from one single case, making it questionable.
Considering the non-alarming indication of topical minoxidil and its poorly documented effects in alopecia, avoidance of use in both pregnancy and breast-feeding seems advisable.
Senast ändrad 2018-09-20