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Medications Can Cause Smelly Gas

Flatulence is rarely mentioned as a drug side effect. But many medications can cause smelly gas. Here are some examples. What should you do?

No one likes to talk about flatulence. That includes your doctor, nurse practitioner (NP) or physician associate (PA). It’s one of those things that everyone pretends doesn’t happen. And yet we all make gas. It is a natural biological process. The average is about 14 “events” a day. One of the world’s leading flatologists (an expert on flatus) has written that anything less than 22 flatus passages per day is normal and requires no medical intervention. Most folks blame their gas on food. Little do they know that many medications can cause smelly gas.

Has Your Doctor Warned You About Flatulence As a Drug Side Effect?

Most health care professionals are not likely to cop to causing flatulence. And yet many of the drugs they prescribe can contribute to gassiness. When was the last time you were told that a medicine you are taking could make you gassy?

This is just a hunch, but I would bet that a lot of folks have been blaming their gas problems on dietary indiscretion while ignoring the medicines they swallow every day.

Let’s start with lactose. It is found in many pills because it is an inexpensive and convenient “filler.” If there are only a few milligrams of active drug in a pill, it will need something else to bulk it up. People who are lactose intolerant could experience gas and other digestive woes from a relatively small amount of lactose. You will have to get your pharmacist to check the “inactive” ingredients to make sure there is no lactose in your pills if you are in fact incapable of digesting milk sugar (lactose).

Readers Tell About Medications That Can Cause Smelly Gas:

There are hundreds of drugs that can cause flatulence. Here are a few stories that reveal how big a problem this can be:

SC describes what happens to him with the diabetes drug metformin:

“I’ve taken metformin to control blood sugar. Since the beginning I’ve experienced extreme diarrhea, incapacitated for days on end. I cannot plan my day. I Cannot take my meds until after I do my errands. I cannot go out to dinner with anyone for fear of having a digestive episode.

“I have a lot of smelly gas and bloating and painful stomach aches. Socializing with friends is out of my life these days. I’ve always been told by the doctors, when I complain about it, that most people don’t have those side effects. Now I know that isn’t true.”

N.S. experienced flatulence from hormone replacement therapy (HRT):

“For all the years I was on hormone replacement (Prempro), I was troubled by terrible smelly gas. I was embarrassed to go out in public. This and similar drugs are not being used widely anymore. Since being taken off of Prempro I have had no problem with gas.”

Franko suggests a flatulence cushion:

“Taking medication like metformin, and many others, disrupts the digestive system. They will cause excessive smelly gas. Taking other medicine to try to cure it just causes more gas. The best simple solution does not affect body function.

“Try a Flatulence Deodorizer pad from www.flat-d.com. It is an activated charcoal cloth pad that is placed in your own underwear. It absorbs the odor from the intestinal gas. It works for everyone. And you don’t have to wear it when you dont have bad gas or when you are at home. Just put it on when out in public. They have many solutions for different people, even one for people with Horrendous gas when in bed. I use them religiously for many years. They are a wonderful company to deal with.”


Flatulence is not the sort of side effect that is frequently mentioned when your doctor hands you a prescription. And it is unlikely that your pharmacist will mention it either.

Would you be surprised to learn that there are lots of commonly prescribed drugs that cause flatulence? Here are just a few examples:

These Medications Can Cause Smelly Gas:

  • Aciphex (rabeprazole)
  • Ambien (zolpidem)
  • Augmentin (amoxicillin – clavulanate)
  • Avapro (irbesartan)
  • Chantix (verenecline)
  • Cipro (ciprofloxacin)
  • Depakote (divalproex)
  • Diovan (valsartan)
  • Eligard (leuprolide)
  • Effexor (venlafaxine)
  • Evista (raloxifene)
  • Fosamax (alendronate)
  • Hyzaar (losartan)
  • Klonopin (clonazepam)
  • Lamictal (lamotrigine)
  • Lexapro (escitalopram)
  • Lipitor (atorvastatin)
  • Lyrica (pregabalin)
  • Mevacor (lovastatin)
  • Naprosyn (naproxen)
  • Paxil (paroxetine)
  • Premarin (conjugated estrogens)
  • Prinivil (lisinopril)
  • Vytorin (ezetimibe & simvastatin)

Fight Back Against Flatus:

Many health professionals may assume (incorrectly) that gas is no big deal. As you have read above, some people have a hard time socializing because of uncontrollable flatulence. We keep learning that social isolation is a huge health problem. If drug-induced gas prevents people from interacting with friends and family, then this so-called minor side effect can actually contribute to mortality.

What is the answer? First, ask your pharmacist or your physician whether your medicine can cause flatulence. Make sure they actually check since this is not something that is commonly considered.

Find Out About Lactose!

Some people are so susceptible to lactose (the milk sugar in dairy products), even the relatively small amount in some pills can trigger gas. Generic products may not always reveal whether they contain lactose as a filler (a so called inactive ingredient).

Ask if there is an alternate medication that does not cause flatulence.

If you absolutely must take a medication (like metformin to control blood sugar), you may want to follow Franko’s advice. The activated charcoal traps unpleasant odors. Not only are there attractive cushions that you can sit on unobtrusively (on your office chair, for example), but they also make cloth pads that can be used with underwear.

Here is a link to their page.

Flatulence has been a taboo topic for far too long. It is time to open the windows and let in some fresh air and be honest about this problem.

You can also learn more about flatulence and what to do about it (especially if caused by food) in our Guide to Digestive Disorders.

Share your own story about dealing with flatulence below.

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About the Author
Joe Graedon is a pharmacologist who has dedicated his career to making drug information understandable to consumers. His best-selling book, The People’s Pharmacy, was published in 1976 and led to a syndicated newspaper column, syndicated public radio show and web site. In 2006, Long Island University awarded him an honorary doctorate as “one of the country's leading drug experts for the consumer.”.
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