A popular hair-loss drug may be causing babies to suffer ‘werewolf syndrome’ leaving them blanketed in hair, Spanish health chiefs have warned. 

Almost a dozen cases have now been reported in Europe since 2023. 

Officials believe the newborns developed the condition after their parents used over-the-counter remedy minoxidil, which is commonly applied to the scalp to encourage hair growth. 

‘Werewolf syndrome’ causes abnormal amounts of fine hairs measuring up to 5cm long to grow on a person’s face, arms and other parts of their body. 

Known medically as hypertrichosis, it has no cure meaning people must manage symptoms by shaving, waxing or cutting the hair. 

According to Pharmacovigilance Centre of Navarra, a province in northern Spain, concerns were first raised about the bizarre phenomenon in April 2023 after a baby boy developed hair on his back, legs and thighs over two months.

Health experts discovered his father, who had been off work for a month looking after him, had been using a five percent minoxidil lotion on his scalp to treat baldness.

However, when the baby was no longer exposed to this drug, his symptoms regressed. 

Minoxidil, marketed under the brand name Regaine in the UK, comes in foam or liquid form in a strength of two or five per cent.

It’s available on Amazon and in most pharmacies with no prescription needed.

The drug works by helping the blood flow to hair follicles — the part of the skin which grows a hair by packing old cells together. 

Following the case, the Pharmacovigilance Centre of Navarra then assessed the Spanish Pharmacovigilance System and the European Medicines Agency’s EudraVigilance databases.