Giardia Diarrhea and IBS

Find out how the giardia parasite might cause you permanent damage!

Giardia parasites
They’re almost pretty aren’t they? Until they are inside your intestines where giardia can cause intense IBS symptoms and may cause long term damage.
© Can Stock Photo

Giardia diarrhea is caused by a parasite called giardia intestinalis, or giardia lamblia.

Recent studies show that people who get a giardia infection can later develop chronic bowel symptoms, such as diarrhea, constipation, cramps, etc.  Sound familiar?

I wrote on another page about how certain kinds of infections can lead to IBS, but I wanted to cover this little beastie, because I think this is how I got irritable bowel syndrome.

What is a giardia infection?

A giardia infection is called giardiasis by doctors. It used to be called beaver fever, because it was believed that beavers were the transmitters of the disease.

As it turns out many animals can transmit a giardia infection (for instance, dogs can get it). Humans usually get it by drinking or otherwise swallowing contaminated water (like brushing your teeth with the water from a stream, like I did).

Giardiasis symptoms:

Many people can get the parasite and have no symtoms, for others, the symptoms usually show up after about two weeks.

The main symptoms of giardia are intense watery stool and bowel cramps, that can come and go for a few weeks. Here’s the full list of common symptoms:

Giardia symptom list:

  • Young blonde woman with diarrhea from giardia lamblia.
    A few days after hiking the beautiful trails, and being exposed to contaminated water, giardia diarrhea strikes!
    © Can Stock Photo

    Watery stool that may have a horrible smell

  • Abdominal cramps
  • Bloated belly
  • Feeling tired (fatigue)
  • Nausea
  • Weight loss

Hmm. Those sound a lot like IBS symptoms. And yes giardia diarrhea smells particularly nasty. Sorry to mention it, but I thought you should know, if that’s what is happening to you.

How giardia leads to IBS:

This isn’t really known, but it is thought that, like other infections, giardia causes changes to the way the nerves of the bowels work. Somehow this leads to visceral hypersensitivity, bowel cramps, diarrhea, bowel spasms, trapped gas, and constipation.

In other words giardia can lead to chronic IBS symptoms.

Research into how it actually happens is ongoing.

Giardia treatment:

I never got my giardia diarrhea treated. I didn’t know how serious it was.  Treatment is simple, and I’m sorry I didn’t have it.  Don’t make my mistake.

The standard treatment for giardiasis is a prescription for antibiotic medicine. The commonly used antibiotic for this parasite is Metronidazole (I have no idea how to pronounce THAT :).

When to see a doctor:

If I were you, and I thought I had giardiasis, I’d seek treatment right away.

If you don’t have IBS, you might get it. And who knows, it might make your IBS worse if you already have it.

Whether you think you have a giardia infection or not, you shouldn’t go more than a week with the symptoms mentioned above (at least in my amateur opinion).

You can get dehydrated or have other complications.

Get help if you need it, even if it means talking about your bathroom problems!

What about you? did you ever have giardiasis?

Do you think it led to your IBS symptoms?

Let people know in the comments section below!


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  1. P hancock says

    My son and I had giardia, probably from the baby pool of our neighborhood pool. We both have stomach issues often. We were treated for giardia at the time, yet we still suffer ongoing stomach problems after eating. Bloating, discomfort, diarrhea. Can we be retreated with the antibiotic?

    • says

      I would think the first thing to do is to check for a giardia infection. Your doctor would have to decide if antibiotics are required. Sorry I couldn’t answer you question one way or the other.

  2. Ben says

    I was treated for a giardia infection 20 years ago at the age of 6. Ever since, I have had chronic IBS. 20 years later and it persists!

  3. vicki says

    Six years ago I got guardian from grand daughter who most likely caught it kindergarten. I have been lactose intolerant ever since but not the child. I have ibd symptoms and am convinced that it damaged the villi and ability to make many enzymes. I am now 18 pounds underweight and also developed allergies. Albendazole is better to take according to the doctor. Tests did not prove giardia. It is gard to see in tests. I also had cdiff which can also damage the colon and some similar symptoms. Anyone’ if you think you might have this evil parasite get help asap. There is now some report Online of guardian not getting better due to mala sorption of oral mess and treatment needed by iv.

  4. iamkinghenry says

    I got chronic giardia and had it for like 2 years before treatment. It’s been 8 months after treatment and my bowels are still messed up. I had O&P samples tested at 3 & 6 months that were negative after treatment so it looks like my system is damaged. I guess only time will tell if it returns to normal.

    I think I got it simply by wiping my hand across my mouth after getting it wet by playing fetch in a stream with my dogs.

    • says

      Something so small, you can’t see it. In a passing droplet of water. And yet all the misery this can cause. I hope time is kind, and you get some relief.

  5. says

    I had ibs most of my life. For some reason it stopped about 12 years ago. After a recent bout of giardia it has returned. I was treated for the giardia and those test are now showing neg for the bug. I am not looking forward to ibs again or being told to just eat more fiber and it should clear up. I hope the treatments for ibs have improved.

    • says

      THAT SUCKS. After 12 years, you’d think a person would be safe. I can’t say I’ve seen many improvements in care, but that’s just from the outside looking in. Maybe the doctors have something up their sleeves. So far I haven’t seen much of that though. That doesn’t mean you can’t find the right person to get you fixed up! Good luck! – Shawn

  6. Sam says

    I got Giardia in 2009 in India, I carried it for about 6 months before diagnosis (mainly due to UK doctors being very disinterested). I dont experience extreme IBS symptoms, but it comes in bouts, not particularly painful, just uncomfortable and inconvenient. I think that these bouts do seem to relate to moments of emotional stress, changes (like moving house – as i am doing now…)

    This research sounds interesting! Could also be worth experimenting with reducing Lactose. Are there any other foods or things that are suggested to cause OR aid IBS symptoms?

    • says

      While I’m not a medical proffessional, or even a dietician, I HAVE read in lots of places that stress can set off IBS.

      If I were you, I’d seriously consider a food diary to see if there is a connection between something you’ve eaten and bowel trouble. I’ve read about all kinds of foods that can trigger IBS, so giving you a few in a list won’t help. It depends on YOUR system. Please see the food elimination diet page.

      I’ve read that it can take a few days for foods to cause problems, so looking back over the last few days, may be worth something. If your ready to take it to the next level, I’d consider a naturopathic doctor and/or dietician. They can usually help you find foods that may be giving you trouble. All the best, and good luck! Shawn

    • beezwings says

      I too had Guardia twice while in India, and have noticed strange digestive issues similar to yours in the years following, particularly when stressed or emotional. Recently, I have been trying to follow a low FODMAP diet because I think I may have fructose malabsorption (linked with IBS). Even after cutting out high-fructose foods such as onions, apples, coconut milk, and honey for just a few days, I’m feeling so much better.

  7. Misti Piette says

    I caught Giardia in Rome. I had it for a year and developed IBS-D and food allergies. I have been taking Triphalla and it seems to have really helped. It is suppose to help your body heal its entire Bowel system. I would also look into candida overgrouth as it can flourish in a giardia enviroment. I am hoping to clear up my food allergies as they seem to be what is now triggering my IBS.

  8. Alex says

    I got giardia a year and a half ago, it showed up in stool tests. Majority of my symptoms remain nausia, ill feeling gets to me the most never really had diarrhoea from it which puzzled the docs. Had for a few month before treatment. Stools, duodenal biopsy are negative now. Hope I get better in time. Also suffer from fatigue and burning skin which developed slowly after infection just hoping doesn’t get any worse.

    • says

      Alex, I sincerely hope things don’t get any worse too. If the giardia is gone, hopefully things won’t get any worse. I believe some people develop problems with foods after a gut infection. Is it possible that you have something like that going on? I have a page here about . And there is also info called . Maybe there are clues there you can use.

      Thanks for letting other people know about your experiences. May you get well soon! – Shawn

  9. Jodie says

    I was infected with Giardia about a year and a half ago in Guatemala. I think I only had it for a few weeks but the symptoms were chronic, I have never felt so ill.

    Since then I have a really low tolerance for alcohol, even a little makes me so sick the next day. Do you think it could be connected?

    • says

      I do think so. I’m biased because of my own experience, and don’t have science to prove it, but yes I think that alcohol and other bowel sensitivities can start after such an intestinal trauma.

  10. stresssedmum says

    My son, who was 2, caught giardia after going to the London to the winter wonderland in Hyde Park. He was eating some food and fell over on some soggy food wearing his gloves, He refused to take his gloves off and carried on eating. The next day he was throwing up, his belly was bloated, he was getting belly cramps and this carried on for 3 – 4 months. We took him to various Drs explaining what had happened and that we thought that that was the trigger. They all told us that it was highly unlikely. He developed a dairy and gluten intolerance, lost confidence in eating because every time he ate he was sick and lost a lot of weight. Thankfully we saw a consultant who asked us what we thought was wrong with him and listened to us and treated him with some powerful antibiotics that wiped out all of the bacteria in his gut. We were told it would take a year for him to get better. We have been back to the Dr a few more times this year because our son had started getting belly cramps and have been told there’s a chance he’s either got IBS or abdominal migraines. I, personally, think it’s most likely IBS. I really feel for him being so young and having something like this, be it ibs or the abdominal migraine, that can at times be debilitating. I am also furious with the Drs for not having listened to me and for not having taken a stool sample to test for this. I did request one but was told that I was not a Dr and to let them do their job. Giardia is absolutely horrible and I just wish that Drs would make this a routine test when people come to them. It can make a big difference if it is caught early. The ironic thing about when my son fell on the dirt was that my sister was laughing at me because I was stressed because I’d left my hand gel at home, not sure if it would’ve made a difference but can’t help wondering..

    • says

      That is HORRIBLE! There is NO pain like watching your child suffer.

      First let me say that I’ve looked into this, and it seems that alcohol based hand sanitizer would NOT have helped against Giardia has an outer shell that protects it from a lot of things.

      Did the consultant or anyone ever test for giardia??? You don’t mention it.

      The reason I ask is because (I’ve read) that giardia symptoms don’t show up until at LEAST 5 days after exposure. So while your son may have had giardia, it likely wouldn’t be from the glove incident. I got that info here :

      As far as still being sick, I wonder if the the powerful antibiotics you mentioned wiped out important bacteria that your son needs for a healthy gut, or if the original problem (giardia or not) still remains to a lesser degree.

      I talk a bit about helpful bacteria on the page.

      I’m looking more into the many kinds of bacteria in a healthy gut, and I hope to have more info on that soon.

      I hope something here helps you find some answers. – Shawn

    • anna says

      Hi, I am just wondering how is your son doing? My 2 year old daughter got this bug from day care. I got it later on from my daughter since them my and my daughter stomach neve returned to the normal.
      My daughter sinc then have loos stool with undugested food in stool as well losted weight. She also slowed dow with her development.
      Also developed food sensitivity. I recently stop working as I can not keep enything down.
      It just break my heart to see my daughter suffer like this.

  11. Christine says

    I visit Zambia 4 times a year…Iam from UK I had Giardia 5 times in one year and it was Chronic..I started taking MSM along with Allicin tablets..and I was Giardia free for over a year..seemingly the MSM puts a coating on your intestine which makes it slippy therefore the cysts..which have small suction cups at the end of their feet are unable to stick to yr intestine and get flushed out…anyway I now have IBS have tablets for that and have to get endoscope as bloods and stool samples came back clear…glad I saw this link on the Topix Forum that I joined when I got Giardia…. It all makes sense. Thankyou.

  12. Laura says

    My son was 16 when he caught Giardia in a cold Texas lake while in a class trying to get scuba certified. It was several months later when a doctor finally caught it and eradicated it with homeopathy. During that time, he developed stomach issues, lung issues, and allergies to wheat, corn, and dairy. It’s 2 1/2 years later and he is hoping to go away to college in a couple months. We have gotten used to the food changes, but the fatigue is still a big issue. It’s terrible and we don’t know what to do to make him better. Any ideas?

    • says

      Hi Laura, I am not a big believer in homeopathy. Naturopathy yes. I would take him to a regular doctor (I like osteopaths). There are treatments for persistent giardia infections. I hope it helps.

  13. Barbara Osorio says

    I was infected with Giardia in Chile while in early stages of pregnancy. My ob/gyn sent me to see an infectious specialist who thought it best not to treat me because of the pregnancy. “In 6 months time it will be out of your system anyway.” Testing after 6 months indeed showed that I was no longer infected but in the 6 years since I have developed IBS, Chronic Fatigue, and Fibromyalgia (in that order). I have suffered unrelenting fatigue and pain. Had to be on disability for 2 years, and then willed myself back to work part time, while still struggling with symptoms. I am fat, lactose, fructose, and carbohydrate intolerant. The FODMAP diet helps control the gas and bloating associated with the intolerances. Digestive enzymes and bile salts taken with meals also helps. I recently came across a very good website that I feel accurately describes IBS, and provides a comprehensive list of lifestyle and treatment options based on the results of research trials, including diet, physiotherapy, probiotics, and medications to resolve gut motility problems. I am hopeful that this regime will help improve my condition.

  14. Kim Valade says

    I have no idea where I got my giardia infection. But I had severe diarrhea for over a month (started in late feb. until April when I was treated) and many visits to the doctor with many stool samples, but no answers. I literally couldn’t leave the bathroom. My husband had to stay home from work to take care of our son who was 8 months old at the time. At one point, I went to the ER and the doctor gave me a super strong version of immodium because he just figured I had a viral gastroenteritis infection that would pass in 10-14 days. That little pill worked great! But then I ran out. And I was back to where I started. My doctor finally acted on a hunch. She thought maybe I had giardia because she had just treated a 10 yr old boy for it so it was on her mind. It was never confirmed by stool sample but she gave me the drug anyways. Within 48 hrs, I was feeling much better and by the end of the medication I wasn’t living in the bathroom anymore and could leave the house. But now I’m left with ongoing digestive problems. I still gave loose stools every day (1-5x per day), some cramping, lactose, caffeine and alcohol intolerance. I don’t absorb anything that I eat. It’s really discouraging. I would give anything to be constipated for a few days haha. I am currently taking a probiotic and some glutamine stuff from my naturopath. So far nothing is helping. The doctor did tell me that it can take many years for bowels to return to normal after a giardia infection. Now I’m just trying to figure out how to cope with it I guess

    • Rosie says

      Hi I have had giardia and cured it but also got reinefected again. This parasite is a nightmare to shift. I do not believe in IBS that’s just a fancy made up name for Irritable bowel syndrome. Can I say if you catch pinworms you take Ovex but it will only kill the worms not the eggs, so it is recommended to take another dose 2 weeks later to kill the hatching eggs.
      Most people take Metronidazole for 7 days, I believe that the remaining cysts that metro does not kill, just hatch out and it all starts up again. I would say giardia works on the same system as pinworms. So taking another dose could possibly kill the remaining cysts when they hatch out. Finding out the circle of hatching would help so you know when to take the second dose.
      You can take 7 days of metronidazole and on the 8th day take pure OptiMSM flakes in water each day, you need to stay on it to remove any cysts buried in the small intestines in stomach lining. They can remain in there for years I read before hatching out. I have told quite a few people who have said they have giardia about using OptiMSM and they have come back to me saying all symptoms have gone.
      I buy mine from because it is the genuine pure OPTIMSM by Bergstrom. You can take Allicinmax capsules one a day to kill bad bacteria, you can buy them off the net or Boots online in uk.
      When I cured giardia I felt back to normal no after effects and I was clear for a year! So I do not believe in all this after IBS, I think the parasite is still there. How can doctors say after treatment oh your test is nagative now, you are cured. You can not reply on these test results, you can get a nagative but still have giardia, so no way can they say you are clear by a test after medication and be 100% correct, these tests are so hit and miss, so they can only guess or hope by saying you are clear. or they then just say IBS. I believe if you still have symptoms you could still well have the giardia. Nothing to date kills these cysts inside you, they can only kill the parasite.
      My advice would be take the Optimsm and stay on it until all symptoms are gone and if the symptoms return go back on it.
      Scroll down this website to parasites and read the uses of MSM
      There are no guarantees on anything, you can only try these things and see if they work for you. I am not a doctor but I have experience of this horrible parasite and it is not good. My son had 6 faeces tests for giardia and all were negative, the doctors told him you DO NOT have giardia it was all in his head, 7th test came back positive. He suffered years all kind of tests they gave him pipe down his throat and samples taken were clear you DO NOT have giardia. A vet told me she goes by symptoms because these tests are so unreliable as they only take a small part of the faeces and test it, so by not doing the whole sample these cysts can be missed as they are also intermittent shedding, so could be in one sample but not another.
      Cut sugar out, high fibre low carbs, cut out junk food, eat healthy fresh green veg and chicken or meats. Drink plenty (bottle water) can add fresh lemon to it as high in vit’C’ lemons act as stomach acid, so if low on stomach acid can cause you not to get rid of parasites and stomach bloat (read up on low stomache acid) Take a good powdered probiotic eat plenty of organic yogurts no added sugar natural bio yorgurts. A good vitamin & mineral per day. You must build up your immune system. Fresh coconuts give your body a boost and contain MCFA which is only found in mother milk and this kill giardia.
      I hope this helps you!

  15. sharmane says

    hi my son who is 4 was diagnosed and treated for giardia when he was 2 , he’d unfortunately had it approx 6 months before getting treated :( he has has consistent diarea since , he cant control his bowels and I am reconsidering whether to put him into kindy next year as he isnt toilet trained and ofen nervousness and stress make him more vulnerable and frequent in passing diarea. the other thing that I cant seem to find many cases of are that in every poo sample I have done (at least 7 since he had giardia) other common bacteria shows positive (eg so he has had another 4 antibiotic treatments for blastocystis and others I cant pronounce) we are now at the point of changing to a different antibiotic as he has had metrizinole too many times :( although the giardia has not returned we have no doubt that this terrible disease has caused this chain of reactions and nothing gets better or easier for him. after a few elimimation diets, we are now gluten free, although it cant return him to normal it certainly helps, we stay home most the time as this is where he feels most comfortable. I hate that I cant take this away for him and let him live a normal life that every 4 year old deserves, I will never give up fighting for my baby boy ..

  16. Jeanette says

    I think iv got giardia, i have been suffering nearly three months and my doctor does not keep on top of test and symptoms. Im getting far worse as time goes on. My mouth is pure ulcered as my gut n bowel are , i also have a duodenal ulcer and is effecting me more with this infection. The more i read on this infection the more i dread trying get shut of it. I have 2 cats and 1 dog, my cats
    Are not behaving the usual , 1 kind of loose pale ugly smelling poo and the other cat awful smelling poo and constantly hungry omg

  17. Art says

    I had a litter of puppies 5 years ago and they had Giardia. I kept one of the puppies and for the past year, I had all of the symptoms described for this parasite. I remember that the vet told me it’s often a false negative, but the oily, smelly stool was the give away. Treatment included metronidazole (aka Flagyl). After having food poisoning several times, and constant cramping in my lower abdomen, I decided to self medicate. Flagyl is available over the counter in Canada, and not too costly. I took it and was much improved. I recently had some oral surgery that was treated with Ampicillin and prednisone. For the first time in a VERY LONG time, my bowels are working as they should, normally! If they doctors can’t find it, they aren’t going to treat it! I decided that it was worth a try, and it worked for me.

  18. Aaron says

    I had giardia from a lake trip, Iwas on Flagyl for several months bc i kept testing positive for Giardia. Ever since my stomach has been a living nightmare. Burping, belching, horrible smelling gas, loose yellow stool or diarhea. Major indigestion, and heartburn. Headaches and extreme fatique. I’m an otherwise heathly 27 y/o male. I’ve developed all kinds of allergies and have a lot of inflamation throughout my body. After living with the stomach problems now for a few years, now all my joints and muscles are causing me problems.

  19. Penelope says

    I’m one of those self treaters also. I did go to the doctor and was thrown in the IBS catch all. I felt strongly that it wasn’t IBS. Mine started after I had knee surgery. Standard symptoms of horribly smelly gas and loose bowel movements (the only advantage is I lost 10 pounds). After a year and half I came across an article about giardia and IBS. I felt that I’d rather just try a course of the medication rather than specialists, blood and fecal tests (I did get a colonoscopy, it was time) that would not necessarily show anything. Within 4 days I was better and stayed that way for 3 years! I did another course just recently. The symptoms slowly sneaked up on me until I was getting completely embarrassed about the smells I was exuding. Again, within 4 days I was completely better. I’ve told other friends about it but until doctor’s stop throwing everyone into IBS without confirmed diagnoses of possible other pathogens then people will suffer. I’m back to eating my beans, broccoli, cabbage, milk and all the other gas makers without making my family want to kick me out the door :) (I have dogs who play in streams and I garden and sometimes eat raw meat but not as much as I did). Good luck to anyone who is looking for something other than the IBS catchall.

  20. matoca says

    I was exposed to Giardia during a visit to the Adirondacks in 1989. We stayed at a very old B&B that had well water and the property was on a mountainside near many streams. After returning home, within a few days, I developed sudden and explosive diarrhea. I went from perfectly normal to abnormal. I knew, from my visits to the Adirondacks, that “beaver fever” was well known to hikers, this was not some mysterious disease to me. But to all the physicians I saw it was as rare as a tropical disease.

    Visits with physicians were frustrating as they were really “accusing” me of having IBD and claimed that I had probably had it since I was young. I stood firm and said no, I have never had a problem until this visit to the Adirondacks. The gastroenterologist I first saw refused to treat me with metrondiazole and gave me Metamucil instead. One gastroenterologist was willing to give me Donnatal for a long time. But I otherwise have really been treated very badly by the medical community.

    That has been my story continually since then. My colonoscopies always show diverticulosis and the attending surgeons always admonish me to eat more fiber. I have always eaten a very healthy diet but I also have suffered for a very long time with problems. I am tired of being blamed for my illness.

    Several years ago I developed left sided abdominal pain and reluctantly made a doctor’s appt. I saw the nurse practitioner. I was startled when she prescribed metrondiazole and another antibiotic! Within a few days I was feeling better than I had in many many years. I was unwilling to share all this history with her and just kept quiet about how “much better” I was. That single treatment made some permanent improvements in me, but not 100%. I knew for many years that metrondiazole would help me, but no one would prescribe it to me.

    Now I read that Giardia is finally recognized as the most common associated condition for long term IBD. I am still leery of visiting any physician again because of the shame and embarrassment these visits cause. What should I do? That PA is no longer available to me. Are there any significant improvements that can be made now after this much time has elapsed? Should I just accept where I am with this now?

  21. Jennifer says

    I believe I caught Giardia from drinking water in a cabin in Colorado that said it was spring fed. The belching, bloating, diarrhea, cramping etc. went on for 5 years. My husband drank the same water but was fine. So much depends on your immune system at the time. Doctors just said I had irritable bowel. When I complained that I was doing everything they said with no improvement, they had no explanation except irritable bowel. I finally went to an integrative doctor who did more stool testing and the Giardia was found. I think a lot of damage was done in those 5 years. My symptoms were very similar to someone with Celiac disease which I did not have but it also damages the villi of the small intestine. I took massive doses of Metronidazole for double the length of time. I wanted that protozoa gone! Unfortunately, I have been left with many food intolerances and digestion issues to foods like dairy, gluten, fats, high fiber, and sugar. I actually did not lose weight with giardia but boy did I feel bad. The fatigue was unbelievable. I would have to rest on the couch in the middle of washing dishes. I could get up in the morning and want to go right back to bed which is not me at all. I am very active and like to run and ride horses. My giardia was treated in 2012 and the IBS type issues still persist. The severity of the cramping, diarrhea, constipation, and bloating varies. I may have a month that I have cramping diarrhea every morning and then it will subside for a few weeks. I may get constipated for a week or two and then return to relatively normal. My fatigue is gone along with the muscles aches and pains. I feel much better but have a bad feeling these GI issues will probably be a challenge the rest of my life. I did not have much luck with GI doctors listening to me but the Integrative doctors took the time to actually listen to my story. When I had the giardia I had 2 surgeries for endometrioma’s. The OB doc would tell me to go to GI and the GI would tell me to go to OB. My advice to someone trying to figure out symptoms is do as much research as you can, talk to lots of people, and get in with a good integrative doctor who will look at the whole picture of your health and not just try to stuff you in their box. Because if you don’t fit in their box, then you get no help or treatment. Doctors started treating me like I was crazy. When I had all this going on with giardia and endometriosis, I went to a doctor for a purplish area by my belly button that hurt and would come and go. The doctor wanted me to admit that I tried to pierce it. That purple spot ended up being endometriosis growing at my belly button which was biopsied during one of my surgeries. If a doctor treats you like this, then find another one. If this post can help one person out there, then it was worth typing.

  22. JaMario says

    I was infected with giardia when I was in the military. I was infected for over a year before finding out the problem and now I have IBS. Mostly episodes of both constipation then diarrhea.

Please let others know what YOU think!