WA doctors are concerned about the growing popularity of a veterinary drug that promotes weight loss but also has serious side effects, with four people admitted to hospital for poisoning this year.
Researchers believe misuse of clenbuterol has spread from elite athletes to the general public after a spike in calls to poisons information centres in WA and NSW.
Since January last year, 10 people have contacted the WA Poisons Information Centre after taking the drug and all were treated in hospital, including four in the past two months alone.
Clenbuterol was developed to treat equine asthma but because of its anabolic properties it has become a popular slimming and bodybuilding drug, known as the "size zero pill".
It is banned in elite sport and is not approved for human use in Australia.
WAPIC head of department Ann-Maree Lynch Calnan said clenbuterol misuse was an emerging problem in WA and the centre was seeing only "the tip of the iceberg".
After receiving no reports of clenbuterol toxicity from 2008 to 2011, the centre has recorded 13 cases since 2012.
"It has become very popular and there are numerous websites discussing its use and benefits," Dr Lynch Calnan said.
"It may be that some people are not aware of the dangers.
"It can cause very fast heart rate, seizures, abnormal heart rhythm, impaired blood flow to the heart muscle and seriously lower potassium levels in the blood.
"Its adverse effects can be serious and prolonged due to its potency and the fact that it is cleared very slowly from the body."
Some patients reported accessing the drug at their gym, where it was promoted as a weight loss pill, while others ordered it online from overseas.
Ten of the 13 patients were women, two were adolescents and the majority came from WA, with several coming from South Australia.
Dr Lynch Calnan said because the poisons centre only got calls from people suffering severe side effects, it was only seeing the "tip of the iceberg."
The NSW Poisons Information Centre has recorded a "dramatic increase" in clenbuterol poisoning, from three cases in 2008 to 27 cases in 2012.
A report published in the Medical Journal of Australia today found the centre recorded 63 cases of clenbuterol exposure over nine years.
Dr Jonathan Brett, from Royal Prince Alfred Hospital, said clenbuterol was often taken in doses "far exceeding the safe therapeutic doses in humans".
He was concerned about the increasing unprescribed use of the drug and the fact it was easily accessible online.
The MJA report noted that the drug was reportedly popular with Hollywood celebrities, and it said consideration should be given to restricting access to the drug by putting it into the same category as steroids
"Diversion of veterinary products for purposes of misuse is a longstanding issue, which also should be tackled," Dr Brett said.
Cyclist Alberto Contador was stripped of the 2010 Tour de France title after testing positive to the drug, which is banned by the International Olympic Committee and World Anti-Doping Agency.
Australian cyclist Michael Rogers was last year provisionally suspended after testing positive to clenbuterol, but he denies deliberately taking the substance and fears he is the victim of contaminated Chinese meat.
In 2011, East Perth WAFL player Kane Goodwin was banned for two years after testing positive to clenbuterol.