coke zero and diarrhea

My previous post in praise of diet coke elicited this comment:

Diet Coke is fine, but steer clear of the Coke Zero. 6 ounces of it and it’s like I injected olestra straight into my body.

I haven’t explored this with scientific rigor, but I too had serious distress stemming from my first 20 oz of Coke Zero.

This post is also serving as my test of Technorati tags:

UPDATE: The passing of time had made me curious about whether this was an anomolous incident or not. Plus my interest was piqued by the trivia that is Diet Coke (regular) is actually New Coke diet, and Coke Zero is classic Coke diet.

So anyway, in a relatively controlled experient, a coworker and I who both had feedback in this first incident tried again. We ate the same exact lunch as several other coworkers to ensure that it would not be related to food. I ate the exact same stuff I normally eat and we both downed a 20oz Coke Zero.

My coworker experience almost immediate trouble. I thought I might have been in the clear, but the next morning I dealt with almost an exact reaction as the last time way back in June. Ruined my whole morning — I almost had to call in Coke-Zero!

Why haven’t more people noticed this? Why isn’t this a bigger deal?



  1. Interesting, I have tried and really liked Coke Zero. Now that I think about it though, I’ve had some "episodes." Maybe I’ll try one more serving and look for a correlation!

  2. I first noticed that half a coke zero results in a "colon cleansing" complete with cramps and loose bowels. Over the last 2 days, four other friends/family have experimented and come up with the same results. What is the ingredient that causes this?

  3. Interestingly, I have an allergic reaction to almost anything with any quantity of Splenda in it. My airway becomes constricted and I my throat swells up.


    Coke zero has no noticable effects in me though.

  4. You guys are full of it. I have been drinking on average of 2 12 oz cans a day of Coke Zero since it came out, and I have not noticed any negative side effects. I have always loved Coke, but I couldn’t stand the taste of Diet Coke. Coke Zero is perfect for me, I could sell the stuff door-to-door.

  5. I love COKE ZERO i have lost 30 lbs in the past 3 days because of coke zero and amphetamines…me and my girlfriend drink it from the moment we wake to the time we sleep……I simply love it.

    -Coke zero fan

  6. i just drank some today for the first time tasted good… but 30 minutes later i started having violent diarrhea… still have it 4 hrs later… I was totally fine earlier today… not blaming it totally on coke zero but its kinda strange…

  7. 2nd time i drank it. no diarrhea but ive been dizzy and shaking and very high lol. Phenylalanine an ingredient of coke zero a teaspoon of it before a meal will make you lose as much as 300g of weight or sumthin. I NEED MORE COKE ZERO!!!!

  8. I wanted tp get my 13 year old son off the high sugar coke he’s addicted to,

    so I bought coke zero instead. A few weeks later after noticing flatulance (farts) that were hard to miss, I puts the two together and on the off-chance it was this change in his diet, I bought caffeine-free diet coke instead (why doesn’t zero come caffeine free?). After a week on diet coke (he switched a lot easier than I thought and does drink it) he says the ‘gas’ has stopped. Interesting… coke must have done studies, I guess flatulence and diarrhea aren’t something you’d want to share with the buying public.

  9. I would have to agree about the diarrhea statement, earlier today being febuary 9 2006 i had a can of coke zero on my way to work, all day i had no problems but shortly after haveing the coke zero i noticed this reaction ( bloating stomach ache etc…) and put it soley on somthing that i had ate.

    after watching a video on the adverse effects of aspertaine on the human body and studies done on animals my interest peak and i found this site….(if youa re interested in aspertaine as well visit

    I have just had my last coke zero, now that i see there are others having these effects as well i can only imagine what else is out there that are affecting me in other ways.

    glad to have this heads up



  10. You had to get you son off regular coke so you bought coke zero instead. Hmmm. Did you ever consider not buying coke for him? And telling him to drink water.? In case you didn’t know – your son is your boss it seems.

    Incidentally, you talk about his ‘addiction’ to coke as if he’d a heroin junkie. Tacit support if you ask me.

  11. has anyone else had the same icky feelingi have since converting to coke Zero????? its almost like i have morning sickness without the actual vomitting..(deffinalty not pregnant!…like a greasy yuck feeling in my throat…and an upset feeling in my stomach..ive decided to give coke zero a miss for a while and see what happens..its horrible..grrr..j

    ust when we thought we found something that would be better that that diet drink taste..i drink 3 litres of water a day but its nice to have coke as a change..but not when i read the things in here..anyone with the same syptoms let me know..maybe its just coincidental…hmmmm but i dont think so…..let me know

  12. I have felt very uncomfortable in my stomach since drinking coke zero…

    it just feels tight and cramped and i dont have diarrhea but its just very uncomfortable bowels and some of the stool is diarrhea like but not all of it…

    i didnt have any coke zero for a few days and these symptoms went away.. i just had two yesterday and now this morning my pains are back.. could it be?

  13. I can also confirm this phenomenon with Coke Zero. It’s like clockwork, and only from Coke Zero in my experience. I can’t believe a bigger deal isn’t being made about this because it’s a really nasty side effect to a seemingly innocuous drink. Coca Cola should be accountable for this and apologize to consumers for not disclosing the side effects, for they surely know about them. Oh well, I guess it’s back to coffee in the mornings.

  14. wow does it really make you loose weight?

    but the thing is i tried a diet which involved just drinking 3 cans of coke zero

    for 2 days and only having a banana in the morning!! but i haven’t lost wieght!

    do i need to do it for longer??

  15. I have a coke zero machine in my office i have about 3-4 cans/ day no side effects here i love the stuff.

  16. Can’t say I’ve noticed any side effects, but as a diabetic who lives on sugar free drinks I have to say that to me Coke Zero is plain awful – it’s ‘thin’, has a metallic taste (even out of plastic bottles) and is not a patch on Pepsi Max (or even regular diet coke/pepsi). Now, I’ve had Pepsi Cino (the one with coffee in it) and that was ‘interesting’, but I got half way through a bottle of Coke Zero and chucked it away as it was so vile.

  17. That’s malarky! I drink 2 liters of this stuff a day and I lost 241 pounds in 1 week (top that Jon!) And yes, I did experience some mild flatulence and diarrhea, but I believe that’s what caused the extreme weight loss. Viva Coca-Cola!

    P.S. This what the alphabet would look like if you took out q and r.

  18. I’ve just had 2 cans of coke zero and I’m definitely having an allergic reaction to it! There is nothing else that could be causing this – my eyelids and throat have swollen (not severly, but noticeably) and my skin feels tingly. This never happened with Diet Coke! I’m intrigued, confused and off to find an antihistamine.

  19. I agree with Steveo, first off your son’s 13 and already addicted to coke( your words) why havent you been buying him juices or gatorade products…and then to get him on diet fat is your son? Sodas and junk food is the downfall of our yourth incase you havent heard any news clips within the last few yrs.
    I have never drank coke zero nor will I it contains aspertain and aspertain has been linked to diabetis amoung other health issues. Your better off to let him have his coke!

  20. I had my first experience with aspertain this past Sunday. Having consumed 8-10 ounces of a sparkling water product, my bowels suddenly let loose. I did not connect with the aspertain till the next day, when, once again I had the 8-10 ounces of the same product and the action repeated itself. Never again.

  21. wow i didnt know coke did that 😮 . ive only drank diet coke 1ce no effects. its weird i tell ya
    how can u lose 241 pounds!?!?!? u must wat 500 :I . :\

  22. Coke Zero rocks my world! i have around 4 cans a day plus a 600ml bottle in there somewhere too…..does it make me poo? i dunno, i guess….i usually have no trouble doing that normally…..

  23. Just loved coke zero! Drank them from the time I woke and even through the night. I also started having explosive watery diahrrea but didn’t connect it for several months. My Blood count was even dropping to anemic levels. Got off all artificial sweeteners and the diarrhea has regressed by 80 % within the first week.
    This can’t be good for your pancreas. I also stay borderline diabetic in spite of NOT using sugar I work in research and am now suspecting that the artificial sweetners even though they are devoid of calories still affect the pancreas into over producing insulin is my guess. I will know in about 3 months when I repeat my AC1 value. I am off for good it’s KILLING ME!

  24. Well Ive been having strange diarrhea for the past few weeks… feels like i have gas, but instead a little watery diarrhea instead…had a few accidents and thought there was something wrong. I started thinking about what changed in my diet and just realized it started at the same time i started drinking coke zero. Bingo. Decided to google coke zero diarrhea and came across many pages of similar comments. How can they sell this stuff with no warnings??? At least the olestra potatoe chips were well publisized. Shame on Coke

  25. I detest Diet Coke, but I can tolerate Coke Zero. It took me a while to put 2 and 2 together, but Coke Zero is definately upsetting my stomach with diarrhea. I’m not drinking it anymore. I’m back to regular Coke, darn it. Water is the answer.

  26. I couldn’t figure out why I was having lots of gas and diarrhea and as a wild guess Googled coke zero and diarrhea. I AM NOT ALONE. I AM A 65 Y/O male and I’ve been drinking +/- 2 cans a day.No more!!!

  27. I wanted to keep drinking Coke Zero for the Zero calories, but it’s leaving me with (-) calories, which could be a good thing, but sometimes I feel like I’m bleeding.
    It tastes great, but the trade-off seems kindda extreme.

    I just had one with my meal, about 10 minutes ago and I already feel liek my A-hole is about to rupture

  28. I recently started drinking Coke Zero. I actually like the taste. It’s sweet, but doesn’t leave me feeling like a “sugar bomb” like regular Coke. I immediately started having stomach cramps and diarrhea, however I didn’t think of this as terribly unusual until my diarrhea continued for several days.. all the while I was drinking Coke Zero.

    I searched google for “health problems coke zero” and found this blog. This confirms it for me. It’s the Zero that’s making me ill. I am actually pretty pissed at Coca-Cola for selling a product that apparently causes mild to severe stomach cramps and diarrhea in a certain percentage of people.

    I have also read that Aspartame, the artificial sweetener in Diet Coke and Coke Zero is a toxic carcinogen. However I blame the FDA for that..

    I really thought it was a great product but my sister was complaining how it caused her stomach upset and heartburn feeling after she drank it. I didn’t have such trouble but I drink occassionaly, yesterday I had to COKE ZERO’s in a span of 6 hrs and my goodness the whole day after that was horrible with stomach cramps and diarehea , what did they put in this thing??
    Funny think is I didn’t have much trouble with DIET COKE which tastes like crap but doesnt upset stomach. There are some real health warning this Coke zero should be displaying on its can, maybe FDA should get involved. Its unfortunate it tastes great but the immediate FOOD POISONING kind of feeling and symptoms are serious health risks

  30. I am SOOO disappointed. I FINALLY found a diet soda that I can tolerate. I have been having the explosive diarrhea and upset stomach. Thought I had eaten something bad. I have narrowed it down to the Coke Zero….unfortunately. Anybody have an idea what is causing the gastric upset?

  31. I drank about 20-30 ounces of Cherry Coke Zero yesterday afternoon and today (afternoon) I am having diarrhea. I can’t attribute it to any food I ate because my fiance ate the same things (except the Coke Zero) and she is fine.

    Great product Coca Cola.

  32. I haven’t experienced the diarrhea, but I have been dealing with some of the worst gas and bloating of my life. And we’re not talking normal, everyday gas. This stuff was toxic! I am a diet soda junkie and instantly fell in love with Coke Zero because it tastes so much like regular Coke. It’s going to be hard to give up!

  33. Yesterday was the second time I drank coke 0, I noticed the bloating and cramping the two times……but I am not used to drinking soda at all, so I thought I was sensitive to the gas….this morning I had diahrrea and regular stool, what was most upsetting and me extremely concerned is that the part that was diahrrea was orange and had drops of oil ……looked liked orange drops of oil……soooo weird….I am definately concerned….did that happen to anyone???? I might go to the doctor….

  34. I have been reading all these blogs about diarrhea and etc. I drink Coke zero, not a lot never really noticed any probs. Matter of fact have lots of it in the fridge right now. Does any one actually know what ingredient is causing the reactions. I’d really like to know. Wonder why coke cola hasnt released any info about this, since its been going on for a while. Mandy Turner

  35. I have not had diarrhea from drinking coke zero but have experienced awfull feelings after drinking it, feelings of strong anxiety sensations, light headiness, irregular hart beat, aces & pains, dull head aces, and if I knew what dyeing felt like I would say it felt how I was. My doctor give me blood tests and other tests and found nothing wrong with me, then he said it was stress but I didn’t feel under stress, he gave me, Trankimazin, to make me relax but the feelings still came so I looked at other things like my diet and as I did I remembered I had started drinking “Coke Zero” normally with “Jack D, Old No 7” at a night time and thats when the feelings normally came or at their strongest (I was not drinking heavily just one or two) I also was not sleeping properly because the feelings that I got I thought I was Diying, I stop drinking the drink streight away and the tablets my doctor gave me now three weeks on I haven’t once had the feelings and can say 99% of me is sure that “Coke Zero” was to blame. this product should be banned.

  36. what the hell is rong with most of people? i drink so much CZ that i prity much live on it! and befor that i was hooked on diet coke and iv never had any problems with it i drink sumtimes if im havin a good day 6Ls a day. i get my coke in australia so i dono if ur coke is bein brood diferently but if ur get the runs from it then uv got problems and stop drinkin it like seriously! stop wingin and just dont do it! ur not being forced!

  37. I have never been an addictive type, but since trying my first Coke Zero two days before Christmas, I have had 1-2 cans a day. Before this, I NEVER drank soda at all. Maybe it’s a coincidence, but at a routine visit to the doctor yesterday, my blood pressure is up for the first time ever in my life! I don’t have any of the symptoms discussed here, but I almost wish I did so I would have even a better reason to get off it!!! I am alarmed that some you feel that diarrhea is a good diet tool! Yeah, that’s right up there with vomitting!!!

  38. Had a Coke Zero this evening, followed by the gnarliest farts of my life. Seriously, I could probably kill people with them. Haven’t had diarrhea yet, but sounds like I might have something to look forward to…

  39. Guys, its called artificial sweetner and caffeine all rolled into one. Alot of people have stomach upset from artificial sugar or too much caffeine. I generally find the degree of upset depends on how much i have had to drink and how sensitive your tummy is.

    Coca Cola wont put a warning out, it’s up to you bright sparks to figure it out sadly. They wont put a warning on sugar free lollys (which give you diarrhea if you eat too many) or alcohol, which can certainly upset your tummy also after a few. So why would coke be any different?

  40. @Lucy, I just wanted to make one point about this… I can drink 10 cans of “regular” diet-coke, no problem. A *single can* of Coke Zero does bad things. Clearly it isn’t just the amount of caffeine or Nutrasweet involved. There is something specific to the Zero formula that causes problems for me, and apparently a bunch of other people as well.

  41. Well, I finally figured it out. I’ve been sick for days and when my husband handed me a Coke Zero this morning, I came in a typed in “Coke Zero and Gas” and found this. No more for me. I loved the taste but can’t stand feeling like this. Bloated, gassy….simply AWFUL. Oh well it was fun while it lasted.

  42. I have that problem whenever I drink zero or regular coke. Pepsi products, RC, Cherry coke, or diet coke in a can are fine. I have eaten the same foods both at home and out at our favorite restaurants. Within 20 min I am about to explode. I am trying to figure out what is in those so I can avoid foods with whatever it is I am allergic to. Interested to see what others say.

  43. i’m so glad other people are getting sick from this. my boyfriend drinks coke zero all the time with no problems. meanwhile, i have 3 sips of it and i start burping and progress to a wretched stomach ache.

    what is it in coke zero that is causing this reaction?

  44. Had a most unpleasant experience with lunch the other day. Gas galore, abdo pain and the most foul diarrhea . Others with me ate the same stuff yet no probs. Only I had the coke zero. Had to be the coke zero ! Thanks to this blog I now know to keep away from the stuff. Many other pleasant drinks out there – why punish yourself.

  45. Not too much to say…i was a great fan of diet coke n coke in general ..but zero is simply intolerable for my stomach even if its only a sip of it….now m more relaxed that i seen its not only me having same problems cause of it…something is definetly wrong with CZ

  46. I love Coke Zero. But I’ve had stomach problems over the last few months and my gastroenterologist cannot find anything wrong. He has suggested that artificial sugars like aspartame could cause this, but I’ve been using Equal for years and drinking other diet sodas with no problems for years. I cannot know if the problems are related to Coke Zero, but I’m going to have to stop drinking it and see if these chronic problems go away.

  47. Bizarre. I just had a can of coke zero about an hour ago, and right now I feel completely bloated. Hasn’t happened before. Anyway, it’s weird how I google this and find your blog dated back to exactly the same day three years ago.

  48. Ive drank coke zero off and on for awhile and it wasnt untill recently when i started feeling that i was having stomache problems. For the past month or two I have been drinking diet coke or coke zero instead of regular sodas and starting last week for about 4 days I had massive stomache cramps, bloating, and of course diarrhea like…. happenings in the bathroom. I have also just felt kind of off. I didnt drink any of it over the weekend and I was fine, than today i had two coke zeros and within 10 min of my 2nd one…. straight to the bathroom. Does anyone know what ingrident causes this? Is it the aspertame?

    … im pretty much done with diet sodas, im gonna stick to regular soda just on ocassion. Id rather have sugar than some artificial chemical.

    in reply to: miss perty:

    It is completely unhealthy to eat one bananna in the morning and drink 3 coke zeros to try to loose weight. Thats like borderline annorexia…… thats an insane diet idea…. just try eating healthier…. your body needs about 2000 calories a day… if u starve it, anything you eat it will just hold on to because your body thinks its starving

  49. Coke Zero was just launched in South Africa. I have been having about a glass per dad for the past week. i have also start suffering from terrible stomach ache for the past week. i even wake in the middle of the night with severe pain. i stopped drinking it about 24 hours ago and the pain is fading!!

  50. I’m so relieved to have found this thread. I’ve had a constantly upset stomach for months and have finally clicked that it started when I started drinking Coke Zero. I haven’t touched the stuff for a week, and I am FINE. The upset stomach is gone. I will never touch that poisonous stuff again. Or any other Coke products for that matter. They will never get another cent of mine.

  51. Dude same here. I had it for the first time and had some “trouble” and didnt even think of it being the coke zero. Then the next day I had another one and it happened again almost immediately. That stuff is has some fucked up stuff in it

  52. I had my first coke zero today and had the exact same immediate trouble. It took about 3 hours to hit and I’ve been havin problems for 5 hours straight. I wanted to try coke zero to decrease the ware on my teeth. Think ill be sticking to regular coke and a straw.

  53. I love the taste of Coke and lay off because I am fat. I found Coke Zero and enjoyed the taste and felt it was closer to regular Coke. However I developed terrible diarrhea. They say to hydrate when you have diarrhea so I drank more Coke-Zero. Diarrhea medicine was no help. I finally realized it was causing my problem and never touch the stuff anymore.

  54. I am suspect also about Coca Cola Zero-Caffiene Free.. I have woken up with the Hershey squirts in my underwear and bed-spread the last 2 nites.. I am 51 years old, and have never had this before.. The only thing I can remember is that I drank a lot of Coca-Cola Zero Diet before bedtime the last 2 nites… I am not 100% sure, but am close to being sure.. I only started drinking this about 2 weeks ago, but I had ALOT before bed the last 2 nites. Maybe 35 ounces

  55. My boyfriend became I’ll on 2/28/17 after drinking coke zero. He is still sick on 3/3/17. How long will this last? He has loss appetite and upset stomach. I’m very concerned.

Leave a comment

Your email address will not be published. Required fields are marked *