He got way too big for his britches.

A toddler began showing signs of puberty after unknowingly being exposed to his father’s testosterone gel.

Barnaby Brownsell had developed a “sizeable” penis, grown pubic hair and gained an incredible amount of muscle by age 2.

His mother, Erica Brownsell of Brighton, England, became accustomed to people commenting on her son’s size, noting that he looked like a 4- and 5-year-old, or joking that he was a “viking” and calling him “Samson.”

Brownsell soon grew worried, though, when Barnaby’s sexual nature began to develop much too early.

“I knew it wasn’t normal,” the 43-year-old mom told Insider. “He’d have massive, sustained erections and his height and weight were off the charts.”

At the age of 1 he was 16 pounds — and gained more than 2 pounds each month thereafter. “It wasn’t fat, just muscle,” Brownsell claimed.

The toddler’s mother, Erica, grew concerned after he developed a “sizeable” penis, pubic hair and gained an incredible amount of muscle.
Courtesy of Erica Brownsell

The concerned mother eventually took her son to be examined by doctors in March, but the medical professionals were also perplexed by the toddler’s advanced aging.

However, blood work would reveal that Barnaby had as much testosterone as a grown man, though other tests showed that he had the bone density of a 4.5-year-old child. The most common causes of too much testosterone are endocrine tumors or congenital disorders — both of which were ruled out for Barnaby.

“It was very scary,” Brownsell recounted. “Nobody seemed to know what was going on.” 

Dr. Tony Hulse, a pediatric endocrinologist at Evelina London Children’s Hospital in the UK, had continued to search for the cause of Barnaby’s rapid growth when one of his colleagues questioned if the child had been exposed to artificial testosterone treatments.

“My husband [Peter] had been using testosterone gel for several years,” Brownsell explained.

Barnaby Brownsell with his dad Peter Brownsell
Barnaby’s father Peter has since switched to testosterone shots to cease exposing his son to the hormone treatment.
Courtesy of Erica Brownsell

Peter was born with a complex testicular condition, which he managed by applying a generous amount of testosterone gel — such as Testogel in the UK or AndroGel in the US — to his skin every day.

The parents shared the responsibility of caring for their son as the “hands-on dad” often watched Barnaby in the morning, just after applying his medication.

“I spent two years of my life thinking that I was protecting and taking care of him — when in fact his own environment was contaminated,” Brownsell said.

Dr. Benjamin Udoka Nwosu, the head of pediatric endocrinology at Cohen Children’s Medical Center in New York, explained to Insider that the absorption of testosterone gel, which is typically applied to the upper arms and shoulders, is “never complete.”

Barnaby Brownsell and his cousin
The Brownsell family is now campaigning to raise awareness about the risks of testosterone gel.
Courtesy of Erica Brownsell

“There’s some testosterone left on the skin, even hours after the application,” Nwosu said. Those who have close contact with the patient are “at risk of direct exposure” which can leak the testosterone into the bloodstream.

High levels of testosterone can be harmful to children as they enter puberty prematurely, leading to early development of acne, pubic and underarm hair, and oversized reproductive organs.

The family is now campaigning to raise awareness about the risks of testosterone treatment gel for children. Their goal is to see a prominent warning message and detailed leaflet instructions on packages of testosterone gel in the UK.

Meanwhile, the US has included a warning label since 2009, after the Food and Drug Administration recorded more than 20 cases of children experiencing puberty at an alarmingly young age due to exposure to the treatment.

Besins, the European pharmacy company that manufactures the gel, did not respond to The Post’s request for a comment.

Fortunately for the Brownsell family, Barnaby’s high levels of testosterone were caught early on, and should have no lasting impacts on his health. His father has switched from using the testosterone gel to shots in order to end Barnaby’s exposure to the hormone.

“The toxin has effectively distorted his appearance,” she said. “We’ll never know what he was supposed to look like at the age of 2.”

This story originally Appeared on Nypost