Diarrhea is your gut’s way of defending itself against invaders. Sometimes they’re germs like E. coli or salmonella. Others times they’re drugs.

An astonishing number of medications can cause digestive tract upset and diarrhea. We’re not talking about loosely formed stool, but rather the mad dash for the bathroom kind. Our readers have shared some extraordinary stories.

One woman wrote:

“My partner, a man in his sixties with ED, began taking Cialis daily. This improved his erectile problem, but a little while later he began experiencing diarrhea of an uncontrolled nature; often he didn’t make it to the bathroom in time.

“Needless to say, he was overwhelmed by this issue and started on a medical journey to nowhere. His primary doctor recommended a gastroenterologist who put him through a maze of tests from colonoscopy to endoscopy (through the mouth), blood tests for parasites and other arcane problems, a scan for ulcers, Crohn’s and countless others.

“Absolutely everything proved negative. He was a seemingly healthy man suffering severe, chronic diarrhea that caused him to lose 30 pounds. He changed his eating habits, trying gluten-free, lactose-free diets, but nothing made a difference.

“The quantity of medications he was taking to stop each of the symptoms was impressive and did not help. His life was changed and he was severely depressed.

“Finally he looked up the side effects of Cialis, since it was the only new medication that coincided with the onset of his diarrhea. He noticed that the information mentioned ‘stomach upset.’ That didn’t exactly describe the tsunami that his problems presented!

“He decided to quit taking his beloved Cialis. Lo and behold! His digestive tract improved: No more Questran, no more Reglan, Librax, or other drugs.”

Drugs for erectile dysfunction like Cialis, Levitra and Viagra can cause diarrhea as a reported side effect. It’s uncommon, but not unknown.

Hundreds of other medications can also cause diarrhea. In some cases it can be extremely disruptive. In other cases it can be life threatening.

“My husband took the drug clindamycin for an infection on his leg. He developed non-stop diarrhea as a result of the antibiotic. He was eventually diagnosed with a C. difficile infection in his intestines.

“He spent nine days in critical condition and 41 days total in the hospital and rehabilitation. He lost his large intestine and gall bladder and has an ileostomy now. The clindamycin complications drastically changed his life.”

Clindamycin can be a helpful antibiotic for certain hard-to-treat infections. But it can also disrupt the ecology of the digestive tract. This allows the dangerous bacteria called Clostridium difficile (C diff) to take over. C diff has developed resistance to common antibiotics and can be hard to cure.

Diarrhea can have many different causes, from tainted food to irritable bowel syndrome. When diarrhea is caused by a medicine, however, it may be difficult to diagnose. People who suspect that their digestive woes are a side effect of their medication should check with the pharmacist and the physician. There may be an alternative treatment less likely to cause the runs.

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  1. Garrett

    I found this page after looking up severe, sudden diarrhea caused by medication on Google. I was interested in information regarding a general cause rather than information about a specific medication and was primarily concerned that my diarrhea may be a direct indicator of a more serious problem with my liver, pancreas, or digestive lining.

    The simple explanation that diarrhea is a way for the body to purge a harmful substance makes perfect sense. Like rinsing soap out of a glass or bowl my body flooded my digestive tract with fluid and opened all the valves. The immediate concern is dehydration.

    To many of those who have commented on this page previously and to others reading in the future, in my experience, adding more chemical substances (medications) to my body when I have been ill has rarely caused an improvement in my condition and has almost exclusively made things worse. When we were children, we ate food, we drank water, we moved about more, and for the most part we didn’t get sick unless there was an immediately identifiable cause. This remains true as we age. I urge anyone reading this to consider your habits, the things you have been doing to and putting in your body and compare them to the good old days of food, water, and exercise to find the cause of your health issue.

  2. John

    If anyone is severely lactose intolerant, you will get severe diarrhea from many medications containing lactose/lactate. Go to https://pillbox.nlm.nih.gov and type in your medication to rule this out.

  3. Dee

    My sister died on Feb. 4th, she had severe diarrhea for a couple of days and when they found her on her apartment floor, they found feces everywhere (she was always so very neat and clean, so she must have been very sick) when they got her to the hospital she was unresponsive and dehydrated. Her Doctor had had her on Tramadol daily and then on Dilantin as she would have sesiures. She also had other meds, but I am really upset to think she had Tramadol twice a day which causes sesiuers and then Dilantin because of the problems. Dee

  4. M. U. M.

    What should be the treatment of sore throat with productive cough with no fever, has taken 2 doses of Augmentin 625mg, which made me develop diarrhea.

  5. steve

    For those with IBS D, Rifaxmin may be your answer. Google current studies. Unfortunately it isn’t prescribed so insurance won’t cover usually, it is very expensive, but generic is avail. in Canada that your dr can fax to.
    PEOPLE’S PHARMACY RESPONSE: Rifaxamin has done well in some early tests, but it is not approved by the FDA. Stay tuned.

  6. mb

    this is mb again and I also have chronic fatigue from all of this with my body from all that started from taking clindamyacyn. I have to take an amphenamine to stay awake to take care of my two children and I don’t eat much either and I cant get rid of this big belly. please help, mb. thank you if you can help me in the right way and what to do…

  7. mb

    I am forty yrs. Old and I had clindamyacin for a little burn that the doctor gave me for infection. And after taking medicine I had gotten the diarrhea and got cdiff. Then I had gotten antibiotics for that after they took me off of the clindamyacyn. Well the cdiff went away but I still have to go to the bathroom at least for 3 to 4 times. and all there doing is now after almost 3 yrs. They did an upper gi now and telling me I have an hyhernia on top of my or above my belly and its very uncomfortable. I feel like I’m pregnant and I’m not pregnant. It’s so uncomfortable I don’t know where or what to do bc I feel so fat. please help, what do I do now?

  8. Chris S.

    Can you tell me which medication(s) for Type II diabetes will cause the least amount of diarrhea? (Having trouble with Metformin)

  9. Eric

    Or the physician will refuse to acknowledge the severity of a reported side effect. I control Daytrana (extended release transdermal methylphenidate)-induced diarrhea with a slew of supplements. I’ve come to terms with the fact that as long as Daytrana is the best solution to my problem that I know of, then I have to accept taking fiber, probiotics, and pancreatic enzymes with every meal to avoid chronic symptoms of IBS-D.

  10. Liz

    Unfortunately, it’s not unusual for doctors to be unaware of drug side effects, even the most common ones. You’ll often get a more knowledgeable response from your pharmacist.

  11. RHS

    Both medicines I was given for type 2 diabetes, Metformin and Glipizide, caused bad diarrhea. I went to the internet to find out whether others were troubled with this problem and found it was a common side effect controlled by taking Immodium with each dose of those medicines.
    When I brought this problem up with my doctors none of them was helpful in recommending a remedy.

  12. S

    I take a mood stabilizer, Depakote ER. They put me on the generic, Valproic Acid. The result was I spent a lot of time running to the bathroom about 20 times a day with diarrhea and internal bleeding. None of my medicines got into my system. I was bleeding from it, and I could not get my shrink to change it to extended release for about three months.
    I drank lots of water the whole time, and finally after I kept losing weight (about 60 lbs.) and wasn’t stable at all they changed it to extended release. I guess I was somewhat non-compliant, which is grounds for involuntary commitment, but I refused to take it anymore.

  13. Karin G.

    I have had the same problem, and I would visit the bathroom 10-12 times a day, always diarrhea. I eat well and exercise, take vitamins, bla bla, so I attributed this to the food allergies I had as a child (to everything). For me, this has gotten worse with age but I do recall having diarrhea all my life. Make a long story short I watched a Discovery Health show in March of 2009 where a middle aged healthy active woman had this embarrassing problem although for her it developed suddenly.
    They called it Habba “syndrome” for chronic sufferers of diarrhea. The man responsible for this discovery is Dr. Saad F. Habba of Summit, NJ.
    People with previously unexplained diarrhea were found by Dr. Habba to have abnormal gallbladder function. Apparently the people afflicted with what is now called Habba Syndrome have gallbladders that pump out way more bile than is necessary for normal digestion.
    Because this syndrome is so newly discovered, most doctors are unaware of it and can overlook running tests on gallbladder function if not prompted to do so by other common gallbladder symptoms.
    It appears that the patients were “cured” of their afflictions simply by taking a drug usually prescribed for lowering cholesterol levels. The medicine is called Cholestyramine.
    As soon as I saw this I paid a visit to the gastroenterologist who wanted to take yet another colonoscopy on me, because now I was having bleeding with each bathroom visit. She agreed to give it to me although didn’t think it would have an effect. Let me tell you on my first dose, my diarrhea stopped! I take it 3 times a day and now I have one, maybe 2 a day, solid forms. If I forget to take it as I did when I went away on vacation, it comes back within 1 day. So it’s something I will likely need for life but it saved me and it feels so good to be “normal”. I hope it works for you too!
    Karin G

  14. gwen w.

    I have had diarrhea for the past 7 years. I have had tests,
    been to three gastro doctors. I have micro, collagenous collitis they tell me.
    They say I am not gluten or food triggered but no matter what I eat,
    I visit the bathroom 4-14 times a day. I did slow down a bit but in
    April I had a dental implant and received antibiotics.
    I have haddiarrhea since April 28. Medicines I have tried but made the problem worse are flagyl, vancomycin hel 125 mg puvulevir, asacol, Lialda, Entocort EC.
    Any suggestions?

  15. RMD

    Come on folks, if you start on a drug and get a reaction like severe diarrhea it’s just common sense to contact your physician immediately and ask to stop taking the drug and see what happens or switch to a different drug. At the very least your doctor should be able tell you if this drug has any contraindications like stomach upset or diarrhea. If you take any drug and notice a change in your body that you were not expecting you should immediately suspect the drug as the problem.
    It is also a very good idea to ask your doctor before you take any new drug if there are any side effects. If he says there aren’t any or he doesn’t know and you experience side effects, get a new doctor.

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