Combo-Pilling for Weight Loss: Diet Pills and Drug Interactions

So on Thursday, I felt the urge to go down and pick up the mail. The day before, both of my housemates had arrived home on the same bus, so the housemate that usually picks up the mail on Wednesdays didn’t pick it up. Of course, since we’re all students who need to go buy food every single week, we needed to know what’s on sale on certain places, so I decided to go down and pick up the mail for them.

And lo and behold, there was a bundle of advertisements just sitting in the box!

One of the advertisements was advertising diet pills. Being a science-literate college student, I was prepared to ignore it. After all, I don’t think I have to explain that the laws of thermodynamics makes it so that you have to use more energy than you consume to lose weight.

Then a header caught my eye. “‘Combo-Pilling’: America’s Hottest Fat Burning Solution!”

Uh oh.

So what is “combo-pilling”?

From the advert:

The highly controversial practice of Combo-Pilling is truly an underground phenomenon. Odds are, if you know someone who’s losing lots of weight, and losing it fast, you probably know someone who’s Combo-Pilling… Why? Because it allows people to attack multiple facets of weight loss — like dropping fat, overcoming stress eating, and having enough energy to work out — at the same time.

A group of pills can make you stop eating when you’re depressed? Really now.

The first thing that I was thinking of after reading that was drug interactions. To use a common example of drugs that should not be mixed, ever, there’s a reason why you can’t drink alcohol and take Tylenol: because of drug-drug interactions. In the case of alcohol and acetaminophen (Tylenol), taking both of these drugs combined can and will wreck havoc on your liver and possibly kill it.

The thing with mixing acetaminophen and alcohol together is that the effect of acetaminophen and the effect of the alcohol aren’t added together. They’re actually interacting in such a way that their effects are multiplied (known as a synergistic effect). As such, the two drugs working together have a much large effect than what you’d expect, because of this multiplication. Hence, more damaging to your liver, which means you can accidentally kill it. Oops.

Other drug interactions can cause antagonistic effects (as in one drug is rendered less effective). An example of an antagonistic effect is the interaction between oral levothyroxine and oral iron supplements; the two drugs interact in such a way that levothyroxine is not as readily absorbed in the gut. (Incidentally, this is the reason why I can’t take iron supplements, ever.) Still others can combine to have effects that are not found in the drugs individually.

This is why you should always tell your doctor what drugs/supplements that you’re taking: because many of these interactions are undesirable and potentially harmful.

Knowing this, encouraging people to just mix drugs/supplements together without checking to see if it was safe to do so isn’t exactly wise. If anything, it’s reckless.

So what does this diet pill advertisement say in terms of mixing drugs/supplements together?

Ever wonder how some people manage to get so thin… so fast? It could be “Combo Pilling”… the über trendy, “underground” practice of combining two or more diet pills to create “supercharged” weight loss.

Oh <bleep>.

Face, meet table. Table, meet face.

Okay, this presupposes a few things.

  1. That weight loss is inherently desirable.
  2. That rapid weight loss is better than slow, steady weight loss.
  3. That mixing two or more diet pills will always lead to faster weight loss.
  4. That mixing two or more diet pills will never have any negative effects, whether with each other or with food or other drugs.

Does anyone see any problems with these presupposed conditions? Any at all?

Our favorite diet pill combination is Zantrex® 3 (the high energy fat burner) and Relacore® Extra (the calming, feel good, “belly fat” pill). One pill picks you up, the other pill calms you down… both of them help you lose weight… but together, oh my goodness!

I feel like I’m currently in Anastasia Steele’s head, hanging out with her subconscious and her inner goddess. And Ana’s squealing over diet pills because she would hate to be fat because being fat means that her abusive asshole of a boyfriend lover and husband, Christian Grey, would hate her forever, even though he forces her to eat all the damn time because she doesn’t eat enough.

Sorry, I’m digressing.

Knowing about drug interactions, this does bring up an interesting question. What the hell is in this stuff?

After some quick Googling, I finally found the lists. Here’s the one for Relacore. And here’s the one for Zantrex.

Now, the links I just put up also did the research on these ingredients for me (and the conclusion is that individually, they’re probably pretty safe, although none of the ingredients have really been shown to have any weight loss properties).

None of these will help you lose weight, so there are absolutely no benefits of taking these individually. But together, you’d be risking serious interactions.

Now, if you’re like me, you tried to plug in their ingredients into some sort of drug interactions database thing. Here’s one from MedScape. And here’s one from

One problem. Some of the ingredients that I’ve typed in are not in their database. These are mostly herbal extracts, so I don’t know what’s in them.

Nevertheless, I did type in all of the interactions that I could, and this is what MedScape gave me (they had a wider dictionary):

Significant – Monitor Closely

  • green tea + caffeine

    green tea increases effects of caffeine by Other (see comment). Significant – Monitor Closely. Comment: Potential for increased risk of CNS stimulation due to caffeine component of green tea. Caution advised.


  • caffeine + thiamine

    caffeine decreases levels of thiamine by inhibition of GI absorption. Applies only to oral form of both agents. Minor or non-significant interaction. Coffee, tea are high in anti-thiamine factors.

  • yerba mate + caffeine

    yerba mate increases effects of caffeine by pharmacodynamic synergism. Minor or non-significant interaction.

  • guarana + caffeine

    guarana increases effects of caffeine by pharmacodynamic synergism. Minor or non-significant interaction.

  • caffeine + calcium carbonate

    caffeine decreases levels of calcium carbonate by increasing renal clearance. Minor or non-significant interaction.

  • ascorbic acid + cyanocobalamin

    ascorbic acid decreases levels of cyanocobalamin by inhibition of GI absorption. Applies only to oral form of both agents. Minor or non-significant interaction.

  • green tea + panax ginseng

    green tea, panax ginseng. Other (see comment). Minor or non-significant interaction. Comment: Use caution when combining green tea with herbs that exhibit antiplatelet effects or anticoagulant activity.

  • green tea + guarana

    green tea, guarana. Other (see comment). Minor or non-significant interaction. Comment: Concurrent administration of guarana to patients taking caffeine may produce excessive caffeine-like side effects, such as nausea, irritability or nervousness. Caution in patients consuming large amounts of caffeine.

Oh dear. The majority of these are “minor” interactions, but still. That’s eight different interactions. and this list is still yet incomplete.

And then you have to imagine these interactions with the other things that people consume, such as alcohol and painkillers and prescription drugs and food and whatnot. This type of thing gets complicated very, very fast. Just adding alcohol and aspirin (two things quite common in most households) brings up the number of interactions to nineteen, with four significant interactions and fifteen minor ones.

So all of the risk, and none of the benefits.

Now does this sound like a good idea to even attempt?

Here is the Feminist Skeptic recommendation: do NOT try this at home. Ever. The risk of drug interactions is too great, and there is absolutely no benefit to be derived. Furthermore, because the FDA does not regulate supplements, you’re pretty much hoping that the manufacturer of any supplement (not just diet pills) are going to act on good faith and not kill you. If you know about laetrile, this is not always the case.

Consumer beware.


3 thoughts on “Combo-Pilling for Weight Loss: Diet Pills and Drug Interactions

  1. afslankpillen

    Dear Alice Sanguinaria,
    Speaking of which, I have been taking Phentermine pills prescribed by my doctor for weight loss. I’ve been doing good so far, except I’m going into the 4th month on them and my body is becoming immune to the pills. My doctor told me this usually happens after a few months. I’m still losing, but barely. Last week I went for my checkup and my doctor prescribed me Topamax to take with the Phentermine. He says there have done studies that when taking the Topamax and the Phentermine together, it can with help the weigh loss. I got a free trial for the Topamax from him so I’m not out any money for trying this PLUS the Topamax is typically prescribed for migraines so it can help with my headaches I’ve been having. My questions is, has anyone else tried this combo? Have you tried any other combo with Phentermine? Results??

    Keep up the good work

  2. Alice Sanguinaria Post author

    I don’t actually take diet pills. I’ve no use for them and think it’s honestly a waste of money, given the fact that the vast majority of ingredients used are 1. unsupported by well done studies and 2. extremely unrealistic.

    You should honestly ask your doctor on what studies zie’s using to claim efficacy. I’m not a medical doctor, I cannot give any medical advice, and even if I were, I wouldn’t be giving them over the Internet either.

    So I’ll be happy to do the research on this topic when I have the time (you’ll have to remind me to do it if I don’t get to it in about a month), but in the end, I’m not a doctor, and if you’re an adult, you don’t have to listen to my opinion.

    If you’re worried about potential harmful drug interactions between Phentermine and Topamax, then I’d start by using either’s or Medscape’s drug interaction checkers. I used Medscape’s for this post because the latter includes a large variety of herbs, something that’s lacks.

    I wish you the best of luck.

  3. Cinzia La Strega

    First, glad to have stumbled into your blog. This post is personally interesting to me, a good reminder of how we need to consider the potential interactions of drugs and supplements. I’m of an age where I’m starting to be prescribed multiple medications, and I’m starting to become concerned about how well my doctor can monitor the potential dangers or side-effects of these combinations..

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