Can You Combine Two Weight Loss Supplements?

There are so many weight loss supplements available but not one is that perfect magic bullet you need.  Some will just help you block hunger cravings, others will turn you into a fat-fighting machine, whereas others boost your performance – or any other of the many purported benefits.  If you want to lose weight with ease, you would obviously want a combination of all of these benefits.  So should you be doubling (or tripling) up on different weight loss pills?

In the pharmaceutical world, taking more than one weight loss drug – or combo pilling – is very common.  Drug companies, doctors and patients are very aware that no single pill is going to help overcome all of the struggles associated with weight loss.  According to a study published in the journal Obesity, 65% of weight-loss doctors are prescribing combinations of weight loss drugs to be used together.

In 1984, the doctor Michael Weintraub got the idea to combine together the weight loss pills phentermine and fenfluramine.  His theory was not only would the combined benefits of these pills further weight loss, but that their contradictory side effects would cancel each other out.  Phentermine is known to cause jitteriness whereas fenfluramine has a calming effect. These two drugs eventually got approved together and marked as Fen-Phen.  By 1997, after numerous incidents of health complications, including several deaths, the FDA removed Fen-Phen from the market.

As any first-year medical student should be able to tell you, drugs simply cannot “cross out” each other’s side effects.  If you take a stimulant drug for weight loss, a calming drug is not going to make all the adverse effects of the stimulant go away. Instead, it is more likely to result in an interaction.

Now, a new combo pill is in development.  It combines the stimulant weight-loss drug phentermine and the anti-epilepsy drug Topamax (topiramate) into one pill called Qnexa.  The company which makes Qnexa, Vivus, petitioned the FDA for approval in 2011 but were denied because of inadequate safety information.  However, both phentermine and Topamax are available individually and any doctor who sees fit can prescribe them together for weight loss.  Already, many people are taking this combination of weight loss pills.  Since it is not approved by the FDA and thus not monitored, we will not be able to find out the potential risks of these combos.

But what about over-the-counter weight loss supplements? OTC supplements are safer than prescription drugs, right? So it must also be safer to combine two OTC weight loss products together.

Before you take any supplement, it is important to realize that supplements are not regulated by the FDA in the same way that prescription drugs are.  Supplements do not have to prove their efficacy nor have their safety backed up by significant research.  The only aspect which the FDA really seems to crack down on is misleading advertising, such as claiming that a supplement is “proven” to give a certain benefit.

Just because a weight loss pill is available OTC, it doesn’t necessarily mean it is safe.  We have seen numerous weight loss pills getting removed from the market years after their appearance because of serious health complications and fatalities – like the notorious ephedrine. By loading up on the weight loss pills, you are putting yourself at risk of serious side effects and may still not get any better results.

There are some cases when it is okay to combine weight loss pills.  “Stacking” is particularly popular in bodybuilding where athletes want to lose weight while also gaining muscle mass.  The same principle can apply to people who are serious about long-term weight loss since muscle mass supports a faster metabolism.  Unfortunately, there is no way to determine for certain whether two safe weight loss supplements will still be safe when used together.  Many of the ingredients in weight loss supplements have not been thoroughly studied and their long-term risks are unknown.

You are almost always going to be taking a risk when you combine two weight loss pills together.  Before you start doubling or tripling up on supplements, you should ask your doctor or nutritionist for advice.  Also, don’t dismiss any unusual symptoms from weight loss supplement combos.  It isn’t worth destroying your health just to speed up the weight loss process. The most potent and proven safe combination treatment for weight loss is, and always has been, diet and exercise.


Sloane, Matt. “Study: Weight-loss combo pill shows promise.” TheChart.Blogs.cnn.com. CNN.  10 April 2011. Web.

Brody, Liz. “Are two diet pills better than one?” Today.msnbc.msn.com. MSNBC. 3 Aug 2011. Web.

“New weight loss pill trialled.” NHS.uk. NSH. 11 April 2011. Web


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