Single Dose of Diet Pill May Cause Harm
Ephedra-Caffeine Diet Pills May Cause Immediate Spike in Blood Pressure and Heart Arrhythmias
WebMD News Archive
Jan. 13, 2004 -- A single dose of a dietary supplement
containing the recently banned ingredient ephedra and caffeine may be enough to
trigger potentially deadly changes in heart rhythms.
A new study shows the popular dietary supplement Metabolife
356, which contains both ephedra and caffeine, caused almost immediate
increases in blood pressure as well as changes in heart beats that could be
The FDA announced a ban on the popular diet supplement
ingredient ephedra, also known as Ma Huang, on Dec. 30, 2003 and warned consumers to immediately stop buying and using ephedra
One Dose May Be Deadly
Researchers say many people are drawn to herbal weight-loss
preparations, such as those containing ephedra, because natural products are
perceived as safe.
"Unfortunately, the perception of safety may be the result
of a lack of data," write researcher Brian F. McBride, PharmD, of the
University of Connecticut Schools of Pharmacy, and colleagues.
Questions regarding the safety of ephedra products had been
raised by anecdotal cases of sudden cardiac death and stroke, but few studies
have examined the safety of these products.
In the study, published in the Jan. 14 issue of the Journal
of the American Medical Association, researchers looked at the effects of a
single dose of Metabolife 356 containing 12 milligrams of ephedra and 40
milligrams of caffeine in 15 healthy adults. Researchers measured the
participants' heart rates and blood pressure before taking the supplement or a
placebo, then again one, three, and five hours afterward.
The study showed that after taking a single dose of the
supplement the volunteers had higher systolic (the top number of a blood
pressure reading) blood pressure (123.5 vs. 118.83 mm Hg) compared with those
who took the placebo.
In addition, those who received the single dose of ephedra
supplement had a longer QTc interval, which is a measured interval on an
electrocardiogram. When prolonged this can lead to abnormal heart
A QTc interval of longer than 30 milliseconds has been cited as
a possible cause of potentially fatal irregular heartbeats that result in
sudden cardiac death. Researchers found that 53% of the participants had QTc
intervals of at least 30 milliseconds while taking the dietary supplement
containing ephedra and caffeine.
Researchers say that since the actual ingredients in Metabolife
356 responsible for these results are not known, people should avoid these and
other similar dietary supplements until more information is known about their