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Lactase and Upset Stomach: What Users Say

Brand names: Lactaid, Lactaid Fast Act, Lactrase, Dairy Ease, Colief, Dairy Digest, Lac-Dose, Lactaid Extra Strength Lactaid Ultra

Upset stomach: mentioned by 16 users (12.1%)

Based on user experiences from 132 Lactase reviews, the following table shows the most commonly mentioned side effects.

All user comments are moderated by Drugs.com. Each review is verified for relevance and screened for inappropriate content. Side effects are user-reported and not clinically verified.

vomiting 44.7%
diarrhea 41.7%
nausea 32.6%
stomach pain 14.4%
upset stomach 12.1%
bloating 10.6%
chills 9.8%
cramps 6.8%
gas 6.8%
sweating 6.1%

Reviews for Lactase

Commonly mentioned side effects
  • She...
  • Taken for less than 1 month
  • November 8, 2020

Lactase for Lactose Intolerance "Absolutely horrible! This is the only thing I’ve done different: try these tablets, and I’m so sick! Awful stomach pains, nauseated, hard bloated stomach, just downright awful feeling! Even by the next day, I’m still hurting! These need to be taken off the market immediately!"

1 / 10
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  • Che...
  • January 13, 2021

For Lactose Intolerance "I started taking lactase pills to help with the effects of lactose intolerance. The first three or four times I took them, they didn't seem to do much in the way of easing the symptoms of lactose intolerance, and my stomach felt a little nauseous. The next time I took it, I became so ill I thought I had the flu. When I took it again, I became sick again with an upset stomach, diarrhea, headache, and muscle aches. So much worse than the symptoms I get from eating lactose. I will never take this again!"

1 / 10
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22 Report
  • Stu...
  • Taken for less than 1 month
  • June 23, 2014

Lactase for Lactose Intolerance "My 10-year-old son would get stomach cramps and diarrhea every time he tried milk. We tried Lactaid on two different occasions a few weeks apart, and both times it caused vomiting. Obviously, something in the pills does not agree with him."

1 / 10
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Frequently asked questions

  • Mz ...
  • Taken for less than 1 month
  • December 27, 2017

Lactase for Lactose Intolerance "This is my second time trying this pill. The first was about ten years ago. Therefore, I brushed the side effects to the side and thought it was just me. This time, I took two pills, and all I can say is that I will never try them again! Maybe it’s just me, but I vomited, had diarrhea, and my stomach hurt for hours. I prayed to the porcelain queen like no other. All I wanted was a mini bar of ice cream, but after feeling so bad, I’d rather deal with the side effects from having the ice cream."

2 / 10
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  • Phi...
  • June 9, 2020

For Lactose Intolerance "I so, so wish I had read these experiences. Have taken this maybe 3 times in an attempt to get less gas and bloating with a bowl of ice cream. The 3rd time, a few hours after the dose, I was asleep and woke up to gnarly stomach cramps. Soaked in sweat, pale green, gagging with nausea during diarrhea. Really horrible. Very dizzy, thought I would pass out. Never again. These pills always gave me weird stomach feelings, but I attributed it to the little bit of dairy. Nope, I’d much rather have some gas pains, lol."

1 / 10
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12 Report

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  • Chl...
  • November 3, 2020

For Lactose Intolerance "I’ve used Lactaid before and can’t remember having symptoms from it. I recently went on vacation and decided to buy some in case I ended up having any dairy. Looking back at just a couple of days ago, I understand why my stomach hurt and why I was nauseous. Today I had just a little bit of cheese and decided to take a Lactaid. I all of a sudden felt nauseous and had stomach cramps. I went on a walk and my cramps wouldn’t go away. I was getting chills and almost some cold sweats. Then, the diarrhea... It didn’t add up that my stomach would hurt that bad from half a slice of cheese. It sounds like so many people have experienced similar symptoms. I won’t be taking this again... I have tried the Equate brand and I don’t remember ever having issues, so I’m curious if there’s a difference in ingredients causing this problem. I’m too scared to try again now!"

1 / 10
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  • Blo...
  • Taken for less than 1 month
  • September 15, 2020

Lactase for Lactose Intolerance "I have been noticing a gradual increase in my sensitivity to dairy. I decided I was going to try Lactaid to see the effect. The first time it seemed fine. So I started using them when I would have a large amount of dairy. This last week I used them 5 out of 7 days, and my stomach started feeling worse and worse each day. Yesterday, I had urgent bowel movements, which have continued almost 24 hours later, and I have had the worst stomach ache. I will not be taking these again."

1 / 10
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  • Ann...
  • Taken for less than 1 month
  • October 19, 2018

For Lactose Intolerance "I have a pretty mild lactose intolerance usually. A big dairy meal can result in an upset stomach, cramping, and gas. I tried a lactase enzyme to hopefully relieve my minor symptoms. Upon taking the pill, my symptoms seriously escalated! I’ve tried it twice now, and both resulted in a terrible upset stomach, diarrhea, and vomiting. Googling the enzyme reveals no side effects, but after looking through these reviews, I’d recommend using it with caution!"

1 / 10
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  • Shi...
  • Taken for less than 1 month
  • July 4, 2021

For Lactose Intolerance "Do yourself a favor and don’t buy these pills. They won’t help you and only give you false hope. I tried these pills out in an attempt to help me wean dairy out of my diet since I usually get an upset stomach when I eat it, but I figured I could treat myself every once in a while by using these. They worked for the first 4-5 times, and then I took two to eat a pizza. Worst mistake of my life. I ended up running to the bathroom and nearly pooping my pants and then projectile vomiting eight times into my bathtub. I seriously felt like my stomach was just a super soaker full of stomach acid and pepperoni. At the time, I figured I had just gotten food poisoning, so I took another one tonight in order to eat an ice cream cone. Tonight is when it clicked that it was the pill, I’ve been toilet-bound for the last three hours and once again find myself vomiting into my tub. Please do not buy these. Save your money and try other milk alternatives if you can."

1 / 10
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  • Coc...
  • Taken for less than 1 month
  • February 22, 2023

For Lactose Intolerance "Tried these about six months ago, and within a few hours, was vomiting along with profuse cold sweating. Thought it was a bug or perhaps the pills were past their expiration date. Tossed that bottle and worked up the nerve to try them again. Big mistake. Two hours after taking them, nausea and stomach cramps set in. Vomiting and the worst diarrhea ever set in soon after. Will not be taking these again."

1 / 10
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  • nic...
  • May 9, 2021

For Lactose Intolerance "I just got done throwing up three times from this product. I have used this maybe 5-6 times, and it has always worked until tonight, where I had a milkshake. I had an upset stomach the entire night and threw up pink cheesecake milkshake. I'd rather have it come out of the other hole instead of my mouth. This product is awful and needs to be removed off the market. I’ll stick with almond milk."

1 / 10
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  • Emi...
  • October 6, 2021

Lactase for Lactose Intolerance "The first time I took this, I experienced extreme stomach ache, believing that my body was just not used to it. A few hours later, I experienced diarrhea. I was very confused, but I used it again the next few days, and the second time, it did the same thing. The only difference was I experienced horrible vomiting, my throat was burning so bad I was in horrible pain. After doing some research about it, many people have experienced the same thing. DON’T BUY THEM, NOT WORTH IT."

1 / 10
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  • Wal...
  • January 6, 2020

For Lactose Intolerance "The first time I took this pill, I didn't experience any side effects. Then I took the chewable a week later, and I had the worst experience that I have had in my life! I was extremely nauseous, weak, shaking, had the chills, and had severe diarrhea. I thought I had gotten sick or something, so I tried the pill again, this time, the side effects were way worse and extreme. I was vomiting so badly, had stomach cramps, couldn't sleep from the pain, weak, shaking, I felt like I was going to pass out. I would recommend this product to anybody."

1 / 10
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  • Jop...
  • Taken for less than 1 month
  • July 21, 2021

Lactase for Lactose Intolerance "I have a mild lactose intolerance. I had a cheeseburger a few days ago, which usually only gives me a small stomachache, but about 15 minutes after taking this, I had a MASSIVE one. The next day, I thought that maybe it didn’t work because I chewed it. So I tried it again with some yogurt (which gives me a pretty bad stomachache but not crazy), and once again, MASSIVE stomachache. DO NOT TAKE THIS!"

2 / 10
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  • Ari...
  • Taken for less than 1 month
  • October 16, 2021

For Lactose Intolerance "Was recommended lactase tablets by a friend that seems incredibly lucky that they don't have side effects. I took one pill before having some ice cream and spent the next day with the worst stomach cramps, nausea, and diarrhea that I've ever had. It's now 6 days later, and I still have a slight stomach ache. This is awful, do not ever take these pills."

1 / 10
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3 Report
  • Ari...
  • Taken for less than 1 month
  • October 16, 2021

For Lactose Intolerance "Was recommended lactase tablets by a friend that seems incredibly lucky that they don't have side effects. I took one pill before having some ice cream and spent the next day with the worst stomach cramps, nausea, and diarrhea that I've ever had. It's now 6 days later, and I still have a slight stomach ache. This is awful, do not ever take these pills."

1 / 10
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Reviews may be edited to correct grammar/spelling or remove inappropriate content. Reviews appearing to come from parties with a vested interest are not published. This information is not intended to endorse any medication and should not replace the expertise and judgment of healthcare professionals.