Doctors are raising concerns about “heightmaxxing,” an online trend reportedly leading some teenagers to take black-market cancer drugs in hopes of getting taller.
The medication drawing attention is erdafitinib, sometimes called “ERDA” or “Erta” online. It is a prescription drug approved for certain cases of advanced bladder cancer. Teenagers, mostly boys, are said to be trying it after seeing claims on social media that it can increase height.
“It’s extremely concerning that teenagers are experimenting with powerful cancer medications in an attempt to grow taller,” said Dr. Stephanie Widmer, an emergency medicine physician in New York City. She cautioned that the drug was developed for serious illnesses, not appearance changes, and that taking it without a medical reason or a doctor’s supervision could have severe consequences.
Johnson & Johnson, which makes the drug, has said erdafitinib has not been approved to promote height growth. Its safety and effectiveness have also not been established for children or adolescents.
There are medical reports of unexpected growth in children treated with erdafitinib for brain tumors. A 2024 study described accelerated growth in two pediatric patients. In a separate case report, a teenager grew more than five inches while taking the drug, but also developed serious skeletal problems.
Doctors stress that such growth is not necessarily healthy. Dr. Jessica Gray, a family physician in Lubbock, Texas, warned that rapid, forced growth could cause structural complications, including damage to growth plates and bone fractures.
Erdafitinib blocks certain cellular pathways involved in cancer growth. Those pathways also have a role in bone development, which may help explain the unexpected growth seen in some young patients.
Widmer said height is largely determined by genetics, and there is no reliable shortcut. Once growth plates close toward the end of puberty, medication cannot reopen them. Older teenagers who take the drug may therefore face serious risks without any prospect of becoming taller.
Potential side effects include lasting vision damage, elevated phosphate levels and other metabolic problems, Widmer said. Other reported warning signs include pain in the hips or knees, mouth sores, loose nails and skin disorders.
The trend has also prompted concern about social media’s influence on teenagers’ health decisions. Online discussions about appearance and self-improvement may expose young people to practices that are unsafe and unsupported by medical evidence, Widmer said.
Parents should recognize that this is more than ordinary anxiety about height, she added: teenagers may be obtaining prescription cancer drugs and taking them without medical supervision. If a child is worried about growth, the issue should be discussed with a pediatrician rather than an online forum.
Doctors advise parents to look out for unusual joint pain or unexplained physical changes, and to speak with their children if they suspect they are using medication bought online. Teenagers concerned about their height should consult a pediatrician before taking any medication.
Widmer urged young people to put their health first, warning that extra height is not worth risking permanent vision damage or other serious, potentially unknown complications.
