Infants developing ‘werewolf syndrome’ after parents take popular hair-loss drug: report

Spanish infants are developing “werewolf syndrome” due to their parents taking a popular over-the-counter hair-loss remedy — with nearly one dozen cases since last year, according to a new report.

Navarra Pharmacovigilance Center has detected 11 cases of hypertrichosis — commonly known as “werewolf syndrome” — in babies throughout Spain and has found that 5% topical minoxidil was used by each of their caregivers, according to a report from El Economista.

Infants who developed hypertrichosis grew tufty hair across their back, legs, and face and in extreme cases can make their appearance resemble a “Wookie” from “Star Wars.”

Investigators believe that topically used 5% minoxidil being used by the infants’ parents is then absorbed by the babies either topically or orally, the report finds.

Minoxidil is the active ingredient of several popular over-the-counter hair-loss treatments including Hims, Rogaine, Keeps, Equate and generic products.

Before this rash of 11 “werewolf syndrome” cases in the past year, there were fewer than 100 documented cases since the Middle Ages.

A 2023 case brought “werewolf syndrome” to the attention of medical researchers and the public after a breastfeeding baby developed hair across their body over two months starting in April, according to El Economista.

During an interview with the family, health officials found out that their father was using topically applied 5% minoxidil, the report found.

When the father stopped the treatment for androgenic alopecia, the child’s symptoms completely regressed, according to the report.

In every case in Spain, the babies’ unwanted hair receded when caregivers stopped topically applying minoxidil solutions.

Another case of a 2-year-old girl with the rare hirsute condition popped up in Malaysia last year — with monarchs in the island nation dubbing her a “child from heaven.”

That child has a congenital strain of hypertrichosis, unlike the cases of environmental exposure to minoxidil that were reported in Spain.

Health experts warn that minoxidil is detrimental to the health of infants and can produce hypertrichosis according to the European Pharmacovigilance Risk Assessment Committee.

A French girl was hospitalized for tachycardia and hypotension after ingesting a teaspoon of minoxidil, according to Reuters.

In 2017, at least 17 Spanish children developed “werewolf syndrome” after minoxidil was accidentally mixed with acid reflux medication, according to reports.