Doctors are issuing an urgent warning to parents after reports that teenagers are taking a cancer drug as part of a so-called “heightmaxxing” trend designed to make them taller.
The trend reportedly involves mostly teenage boys using erdafitinib—known online as “ERDA” or “Erta”—a prescription medicine approved to treat certain types of bladder cancer.
Teenagers are said to be buying the drug after encountering online claims that it can stimulate additional growth.
Physicians strongly advise against taking erdafitinib without a medical need and close supervision. They warn that the drug may cause permanent health problems while offering no proven height benefit.
Dr Stephanie Widmer, an emergency medicine physician in New York City, told Fox News Digital: “It’s extremely concerning that teenagers are experimenting with powerful cancer medications in an attempt to grow taller.
“These drugs were developed to treat serious medical conditions, not to enhance physical appearance. Taking them without a legitimate medical indication or physician supervision can have devastating consequences.”
Medical experts say potential complications include damage to the growth plates, bone fractures, severe pain and harm to internal organs.
Erdafitinib, marketed under the brand name Balversa, is approved by the Food and Drug Administration (FDA) for certain cases of advanced bladder cancer.
Doctors warn that teenage boys are turning to a bladder cancer drug in the hope of gaining height
The medication works by blocking a protein that drives growth in bladder cancer tumors and other cells, helping to slow the progression of the disease.
Earlier research suggested that erdafitinib might also accelerate bone growth in children and teenagers, potentially increasing their height. However, some scientists have challenged those findings.
Erdafitinib is available only by prescription and has been associated with a range of side effects, including vision problems, nosebleeds, changes to the skin and nails, and intense muscle and bone pain.
Despite those risks, reports indicate that some teenagers have obtained the medicine through overseas online sellers.
Johnson & Johnson manufactures the drug, which was approved in 2019 for bladder cancer patients whose disease has not responded to at least one previous treatment.
It is used specifically for urothelial carcinoma, a form of bladder cancer that accounts for roughly 90 percent of the 84,000 cancer cases diagnosed annually in the US.
Rolling Stone reported that a 17-year-old identified only as Zak bought the drug online, paying $300 for a one-month supply in the hope that it would increase his height.
Zak said he grew several inches between the ages of 15 and 17 while taking erdafitinib, but also experienced severe joint pain and repeated nosebleeds. The symptoms became so serious that he feared he might need hospital treatment.
Whether erdafitinib can increase height remains uncertain, but its serious side effects—including nosebleeds and severe pain—are well documented
“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 told Rolling Stone.
Another 17-year-old, identified as James, told the publication that the drug turned his fingernails yellow and caused pus to seep from them. He claimed to have grown about three inches within two months of starting erdafitinib in late August.
“I was five foot five, so it was pretty bad. So then I just knew that there had to be something that could make me taller,” he said.
Johnson & Johnson told the publication that erdafitinib “has not been approved to increase height, and its safety and effectiveness have not been established for that purpose or for use in any children or adolescents.”
Doctors further stress that there is no clear evidence the medication actually increases a teenager’s final height.
The online claims appear to stem from a 2024 study published in the journal Hormone Research in Paediatrics. Researchers observed unexpected growth spurts among children taking erdafitinib for tumors affecting the central nervous system.
During puberty, bones lengthen at growth plates—cartilage zones near the ends of bones. Growth is regulated in part by a naturally occurring substance called FGFR3. Researchers involved in the study suggested that erdafitinib’s ability to block this substance might explain the growth spurts.
Dr Adalbert Raimann, a pediatric endocrinologist at the Medical University of Vienna in Austria and a co-author of the study, nevertheless warned that using the drug carries serious dangers.
“And those receptors we’re targeting with ERDA, they’re present in basically every cell,” he told Rolling Stone. “So we have no idea—not in adults and especially not in kids in this developing system—what we are doing in five to 10 years.”
Once puberty ends, the growth plates close and cannot be reopened. As a result, erdafitinib is unlikely to alter bone growth in adults.
Widmer said: “One of the biggest concerns is that these medications can cause serious side effects, including potentially permanent vision damage, elevated phosphate levels and other metabolic abnormalities.
“We’re talking about adolescents whose bodies are still developing, and exposing them to these risks for a cosmetic goal is particularly troubling.”
Widmer added: “We should be encouraging teenagers to prioritize their health, not teaching them to gamble with it.
“No amount of additional height is worth risking permanent damage to your vision or other serious and potentially unknown medical complications.”
