Actor Sylvester Stallone's high-profile admission of bringing vials of restricted growth hormones into Australia has some doctors worried that other aging individuals may also look to this unproven and potentially risky anti-aging elixir.
According to The Associated Press, the 60-year-old star of "Rocky" and "Rambo" fame was accused of bringing the banned substances into Australia after customs personnel found 48 vials of Jintropin, a human growth hormone (HGH) product during a visit to Sydney in February.
HGH is considered by many of its proponents to turn back the clock on aging, building muscle mass and strengthening bones. For those with medical growth hormone deficiencies, shots of HGH are considered legitimate treatment.
However, Dr. Thomas Perls of Boston Medical Center's geriatrics section told ABC News that it is highly unlikely that Stallone was suffering from such a deficiency.
And he says the aging actor's illegal use of the supplement further highlights the problem of high-profile personalities -- including deceased celebrities Anna Nicole Smith and football great Lyle Alzado -- who have pointed to its dubious benefits.
"When you think of people as prominent as Stallone, it really brings the whole issue of growth hormone and its potential risks very out into the open," Perls said.
For those with legitimate prescriptions for HGH, the substance is a reliable and proven treatment for growth hormone deficiency diseases that may be brought about by cancer and other conditions.
However, the hormone has garnered much greater renown for its purported off-label benefits, as evidenced by its prominence and availability over the Internet.
As a result of the anti-aging claims surrounding HGH, researchers estimate that between 20,000 and 30,000 healthy American adults used growth hormone shots off-label as an anti-aging therapy in 2004.
"I think society in general equates hormones with youth," Perls said. "You can go online or to some clinics and get this stuff without any follow-up."
But while many look to HGH as a fountain of youth, recent research suggests otherwise.
Most recently, a review published in the January issue of the medical journal Annals of Internal Medicine suggests that HGH provides few of the touted benefits for adults who are healthy.
Lead author Dr. Hau Liu of Stanford added at the time that the potential side effects could mean that regular users are putting their health in jeopardy.
Perls agrees, and he highlights the possible risks of HGH use on a site he maintains called antiagingquackery.com.
"Studies in mice show that this probably has the absolute opposite effect," he said. "It may even speed up aging and increase the chances of age-related diseases."
The disease that may figure the most prominently, he said, is cancer. Since certain hormones may spur the growth and division of tumor cells, he says those considering off-label HGH use must consider this potential risk before injecting themselves.
"I think the risk for cancer is real," he said. "Long-term studies have not proven it yet, but it's just certainly not worth the risk."
Other possible side effects that researchers have documented include swelling, carpal tunnel syndrome, and the formation of breasts in men -- a condition known as gynecomastia.
Some studies have also suggested that regular use of HGH in healthy adults can lead to diabetes and pre-diabetic conditions.
And then there is the issue of cost. Regular users of HGH routinely shell out between $500 and $1,000 per month for the pricey shots.
"What makes growth hormone particularly wonderful for the companies who market for these uses it is that it is very expensive," Perls said. "They can make a lot of money."
As in Australia, it is also illegal in the United States for companies to distribute or for doctors to prescribe HGH as an anti-aging therapy. Perls says he hopes highlighting the illegality of HGH for these uses will deter Stallone's middle-aged fans from abusing the hormone.
"My extreme hope is that these people being caught is really bringing the public attention to the downsides and misinformation about human growth hormone."