MDLinxBabies are Developing ‘Werewolf Syndrome’ After Exposure to this Common Medication

⚠️ Rare but High Risk Safety Event
Spain’s Pharmacovigilance Center of Navarre linked 11 infant hypertrichosis cases in 2024 to secondary exposure from caregivers using topical 5% minoxidil for androgenetic alopecia. A separate 2019 Spanish outbreak of 17 cases involved mislabeled oral minoxidil dispensed as pediatric omeprazole, with transient liver enzyme elevation observed.

Clinical Considerations

• Proposed transfer routes include skin-to-skin contact and infant mouthing of caregiver hands or scalp after topical application.
• Reported associated effects beyond hypertrichosis include pericarditis, ECG changes, arrhythmia, and fluid retention in exposed infants.
• The European regulator now requires packaging warnings on minoxidil regarding pediatric contact; the FDA has not issued equivalent guidance.
• Pediatric exposure to adult medications drives more than two-thirds of poison exposures in children, with the highest risk concentrated in ages 0–5.

Practice Applications

• Consider secondary minoxidil exposure in the differential for new-onset infant hypertrichosis.
• Recognize that hypertrichosis typically resolves after caregiver exposure ends, but cardiac and fluid effects warrant evaluation.
• Integrate medication exposure history into routine well-child visits, including topical agents used by household adults.
• Monitor exposed infants for cardiovascular and electrolyte effects beyond the dermatologic presentation.