A new report from the Navarra Pharmacovigilance Center in Spain has uncovered an alarming trend: Eleven infants have developed hypertrichosis, commonly known as “werewolf syndrome,” after their caregivers used a popular over-the-counter hair-loss treatment containing 5% topical minoxidil. This troubling discovery, which has gained attention worldwide, has raised serious concerns about the safety of minoxidil in households with infants.
According to the investigation, these cases of hypertrichosis were caused by accidental exposure to minoxidil, a medication approved by the U.S. Food and Drug Administration (FDA) to treat age-related hair loss in adults. The medication is sold without a prescription and can be applied topically. The report suggests that the minoxidil was transferred to the babies through skin contact or accidental ingestion, leading to excessive hair growth on their bodies.
Hypertrichosis, or “werewolf syndrome,” is a rare condition marked by abnormal hair growth in areas where hair does not normally appear, such as the face, arms, and back. The hair, which can grow up to 5 cm in length, is usually fine and may appear in patches. Though there is no cure for hypertrichosis, affected individuals typically manage the condition by regularly removing the hair through methods like shaving or waxing.
Key Cases and Reversal of Symptoms
One of the most notable cases occurred in 2023 when a breastfeeding infant developed excessive body hair over the course of two months. Upon investigation, health officials determined that the father had been using a 5% topical minoxidil solution to treat his own hair loss. After stopping the minoxidil treatment, the child’s symptoms disappeared entirely, highlighting the direct link between minoxidil exposure and the development of hypertrichosis in infants.
Similarly, all reported cases in Spain showed that once the caregivers stopped using minoxidil solutions, the babies’ symptoms of excessive hair growth completely reversed.
In addition to the cases in Spain, a two-year-old girl in Malaysia was diagnosed with a congenital form of hypertrichosis. Unlike the Spanish cases, the Malaysian case was not linked to environmental exposure to minoxidil but was a rare congenital condition. Nonetheless, health experts warn that infants should avoid exposure to minoxidil due to the potential for harmful effects, including the development of hypertrichosis.
The European Pharmacovigilance Risk Assessment Committee has also raised alarms about the dangers of minoxidil for infants, stressing that even minimal exposure can lead to unwanted side effects. The committee has urged parents and caregivers to exercise caution when handling minoxidil products and to avoid using them in environments where infants could be at risk.
As the cases of minoxidil-induced hypertrichosis continue to grow, health officials are urging greater awareness of the risks associated with this widely available hair-loss treatment. Parents and caregivers are advised to be cautious when using minoxidil in the presence of young children, as even small amounts of the medication can have significant effects.
For now, the best course of action is to avoid exposing infants to minoxidil in any form, ensuring their safety from the unexpected side effects of this popular but potentially harmful medication.
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