Teen Boys Are Buying a Bladder Cancer Drug Online to Try to Grow Taller, Doctors Warn

A bladder cancer drug has become the newest shortcut in the online "looksmaxxing" world, and the people taking it are teenagers.

The drug is erdafitinib, sold under the brand name Balversa. Teens call it "erda" or "erta." It was first approved in 2019 to treat certain advanced bladder cancers in adults. Doctors have also used it off-label in clinical trials of children with rare cancers of the central nervous system.

Now boys as young as 15 are finding ways to buy it overseas, sometimes spending hundreds of dollars a month, according to Rolling Stone's reporting. They post tape-measure photos, day counts and side effects on TikTok.

Why teens think it works

The belief traces to medical reports of unexpected growth in children treated with the drug for brain tumors.

A July 2024 study in Hormone Research in Paediatrics described accelerated growth in two pediatric patients. A separate case report documented a teenager who grew more than 5 inches during treatment but developed serious skeletal complications.

Dr. Stephanie Widmer, a New York City emergency physician and Fox News medical contributor, says the drug blocks cellular signaling pathways involved in cancer cell growth. Those same pathways also play a role in bone development, she says, which may explain the growth in some pediatric patients.

That is a hypothesis about cancer patients. It is not evidence about healthy teenagers.

One teen's account

Zak, a 17-year-old TikToker in New York, told Rolling Stone he has taken erdafitinib on and off since he was 15. He says he bought it from overseas online vendors and initially paid $300 for a month's supply.

He reported nosebleeds, extremely dry skin and severe joint pain before stopping. He says he was bracing for something worse. "I was literally saving money every single day. I was putting money aside from my work and everything just for a medical bill from erda," he said.

Zak says he grew several inches by age 17, going by his own measurements. No controlled data supports that. Whether the drug adds height in healthy adolescents is an open question.

His motive is stated plainly. He says he was teased at school for being shorter than girls in his class, and that the videos he saw online treated height as a requirement for dating. "I don't like other people towering over me, and I don't like having to look up to people," he said. "It feels like I'm not in control."

The boys on his feed describe the logic as simple: everything in life is better if you are tall. They also discuss "heightism," or discrimination based on height. Zak's account shows the social pressure is real to the teens feeling it, whatever the pharmacology says.

What the manufacturer and doctors say

Johnson & Johnson, which markets Balversa, told Rolling Stone the medication has never been approved to stimulate height growth. The company said its safety and effectiveness have not been established for any pediatric or adolescent use.

Dr. Andrew Dauber, a pediatric endocrinologist at Children's National Hospital, has warned that using erdafitinib for height is dangerous. Dr. Adalbert Raimann, a pediatric endocrinologist at the Medical University of Vienna, has cautioned about off-label use of growth-related drugs.

Dr. Jessica Gray, a family physician in Lubbock, Texas, says forced, rapid growth is not the same as healthy skeletal growth. She warns it can cause premature growth plate damage and bone fractures.

Widmer cites other risks: potentially permanent vision damage, elevated phosphate levels and other metabolic abnormalities. She notes that height is overwhelmingly governed by genetics. Once growth plates close near the end of puberty, she says, medication cannot reopen them. Older teens taking the drug are therefore taking on serious risk with no chance of gaining height.

An old pattern

The worry has a precedent. Controversy has long surrounded unapproved human growth hormone use in healthy children with short stature. Erdafitinib is a newer version of the same impulse: self-directed drug seeking, now driven by social media and sold by overseas vendors.

The drug is a prescription cancer treatment with a prescribing label full of serious warnings. The people buying it online have no physician monitoring bloodwork, vision or bone health. Zak's savings-for-a-hospital-bill plan was his own substitute for that.

No regulatory action on the overseas sales has been announced in the reporting so far. The medical question also remains unresolved. The only documented height gains come from a handful of children under cancer treatment, and at least one of those cases came with serious skeletal complications. Nobody has shown what happens to a healthy 15-year-old taking the drug without supervision.