LONDON, UK: A social media trend called heightmaxxing is raising health concerns after teenagers reportedly began taking erdafitinib, a prescription cancer drug, in the hope of becoming taller.
Doctors warn that the medicine is not approved for height enhancement and can cause serious side effects. Although researchers have observed unexpected growth in children receiving the drug for cancer, its safety and effectiveness for increasing height have not been established.
Why Are Teenagers Taking a Cancer Drug to Grow Taller?
Heightmaxxing is part of the wider looksmaxxing trend, in which young people try to improve their physical appearance. For some teenage boys, height has become a major concern because of social pressure, dating expectations and comparisons on social media.
The cancer drug attracting attention is erdafitinib, commonly called erda online. Some teenagers believe it can stimulate bone growth after seeing reports of unexpected growth in children receiving the medicine for cancer.
A report by the Daily Mail highlighted concerns about the trend. A subsequent investigation by Rolling Stone, published on November 5, 2026, documented teenagers experimenting with the medicine despite experiencing significant side effects.
Two Teenagers Report Serious Side Effects
The investigation described the experiences of two 17-year-old boys, identified as Zak and James.
Zak said he had taken erdafitinib intermittently since the age of 15. He reportedly purchased the medicine from an overseas online seller for approximately $300 per month.
He experienced repeated nosebleeds, extremely dry skin and severe joint pain. He also described difficulty stretching his arms and moving comfortably after waking up.
Zak claimed that he gained several inches between the ages of 15 and 17. However, his measurements were self-reported and do not establish that the drug caused his growth.
James, the second teenager, reported more serious complications. His fingernails reportedly became yellow, developed pus and began falling off.
He also described vomiting and stomach bleeding that required hospital treatment. The symptoms affected his daily activities and forced him to switch to online schooling.
James was reportedly experimenting with several other substances, including growth hormone, tamoxifen, letrozole and abaloparatide. This makes it difficult to identify which substance contributed to his health problems.
What Is Erdafitinib and Why Does It Affect Bone Growth?
Erdafitinib, sold under the brand name Balversa, is a targeted cancer medicine. It was approved by the US Food and Drug Administration (FDA) in 2019 for treating certain adults with advanced bladder cancer carrying specific FGFR3 genetic alterations.
The medicine works by blocking fibroblast growth factor receptors (FGFRs), proteins involved in cell growth and development.
One of these receptors, FGFR3, also plays an important role in skeletal development.
During childhood and adolescence, bones grow through areas of cartilage called growth plates. FGFR3 helps regulate the activity of cartilage cells in these areas.
Researchers believe that blocking FGFR3 signaling may explain the unexpected growth changes observed in some children receiving erdafitinib.
However, affecting bone development does not mean the medicine can safely increase height.
What Does Scientific Research Say About Erdafitinib and Height?
A study published in Hormone Research in Pediatrics examined two children with central nervous system tumors who experienced unexpected accelerated growth during erdafitinib treatment.
The research, published online in July 2024, found increased linear growth and changes in bone development, including widening of the growth plates.
Both children had serious medical conditions and received the medicine through compassionate-use treatment after standard options had been exhausted.
The researchers suggested that blocking FGFR3 signaling could explain the growth changes.
However, the study involved only two children and was retrospective. It did not establish whether erdafitinib could safely increase height in healthy teenagers or improve final adult height.
The findings therefore represent an important scientific observation, not evidence supporting its use as a height-enhancement treatment.
What Are the Health Risks of Taking Erdafitinib?
The FDA prescribing information states that the safety and effectiveness of erdafitinib in children have not been established.
It also documents skeletal complications in children aged 6 to under 18 years who received the medicine during a clinical study. These included epiphysiolysis, involving problems at the growth plates, and bone fractures.
Other recognised risks include:
- Eye complications: Central serous retinopathy and retinal pigment epithelial detachment, which can affect vision.
- High phosphate levels: Hyperphosphataemia can cause mineral deposits in soft tissues.
- Skin and nail problems: Dry skin, nail disorders and nails separating from the nail bed.
- Digestive problems: Diarrhea, nausea and mouth inflammation.
Some of these risks require regular blood tests and eye examinations during cancer treatment. Teenagers obtaining the medicine online are unlikely to receive the same medical monitoring.
What Do Doctors and the Manufacturer Say?
Pediatric endocrinologist Andrew Dauber of Children’s National Hospital has warned against using erdafitinib for height enhancement. He explained that treating a diagnosed growth disorder is very different from giving a powerful cancer medicine to a healthy teenager who wants to become taller.
Johnson & Johnson, which markets Balversa, has also warned against the practice.
The company stated that erdafitinib has not been approved to increase height and that its safety and effectiveness for this purpose or for use in children and adolescents have not been established.
It advised patients to consult qualified healthcare professionals and obtain medicines only through verified sources.
What Should Parents Do If Their Teenager Is Worried About Height?
Parents should encourage teenagers concerned about their height to consult a pediatrician rather than experiment with prescription medicines.
Doctors can assess growth patterns, family height, puberty and possible underlying conditions. They may recommend growth charts, blood tests or a bone-age X-ray when necessary.
Some children with diagnosed growth disorders may benefit from specialist-prescribed treatments, including growth hormone. However, these treatments are not suitable for everyone.
Teenagers already using erdafitinib without a prescription should seek prompt medical advice and disclose any other medicines or substances they have taken.
Final Thoughts
The heightmaxxing trend highlights the risks of allowing social media claims to influence medical decisions.
Although researchers have observed unexpected growth changes in two children receiving erdafitinib for cancer, there is no established evidence that the drug can safely increase height in healthy teenagers.
Its potential skeletal, eye-related and other complications make unsupervised use particularly concerning.
Teenagers worried about their height should seek a proper medical assessment rather than risk their health with unapproved medicines.
