The Food and Drug Administration in the U.S. is warning consumers to immediately stop taking a weight-loss product sold on the internet.
Que She is marketed as a "slimming factor capsule" and "an all natural blend of Chinese herbs."
According to the FDA, it contains four ingredients that could result in serious health problems.
Among them is ephedrine, an ingredient in some cold medications that is also a major ingredient in the production of crystal methamphetamine.
'Ephedrine in combination with caffeine and other stimulants may have serious, possibly fatal, adverse effects.' — Health Canada advisory
Health Canada issued its first warnings about the use of ephedrine for weight loss in 2002, and followed up with strict controls on its use and sale in Canada.
"Use of products containing Ephedra or ephedrine in combination with caffeine and other stimulants may have serious, possibly fatal, adverse effects," says a Health Canada advisory on ephedrine.
In the case of Que She, an analysis by the FDA found the drug does combine ephedrine with another stimulant and two other drugs that can be harmful when used improperly.
The stimulant drug in Que She is fenfluramine which was banned in 1997 after studies found it caused serious heart valve damage.
Another ingredient of concern is propranolol, a prescription beta blocker that can pose a risk to people with asthma or heart conditions.
The final ingredient in Que She is sibutramine, a prescription weight-loss drug. A recent study showed an association between sibutramine use and the increased risk of a heart attack or stroke in people with cardiovascular problems.
The FDA says people using Que She should not only stop using it immediately but also seek medical attention.