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Does colostrum cause diarrhea?

Written by the Full Measure editorial team, which sells supplements. Approved for publication by the Full Measure owners. Updated .

Drafted with AI assistance from the sources listed below. How we write these

Quick answer

It can for some people, mildly and early on. Researchers describe nausea, diarrhea, bloating and abdominal pain from colostrum taken by mouth, usually fading after a few days. In a 107 day trial at 0.5 to 1 g a day, digestive symptoms were no more common than with placebo. Ask your doctor if you have a milk allergy.1,2

Key facts

  • Nausea, diarrhea, bloating and abdominal pain are the side effects described for colostrum taken by mouth, usually early in use and fading after a few days.1
  • In a 107 day trial of 0.5 to 1 g a day, digestive symptoms were no more common than with placebo, and no serious adverse events were reported.1
  • In a 20 day trial in athletes, no one taking colostrum reported important digestive side effects, while four of the eight on a whey placebo reported loose stools, bloating, nausea or poor appetite.2
  • Colostrum contains lactose, about 2 to 3% of fresh colostrum, and MedlinePlus lists gas, diarrhea and stomach swelling as results of not digesting lactose.3,4
  • A reviewer estimated that about 120 g a day, the amount one heat study used, would add 70 g of protein and 35 g of lactose a day and could upset the gut.5

What do trials and reviews report?

Nausea, diarrhea, bloating and abdominal pain are the side effects described for colostrum taken by mouth, usually early in use and fading after a few days.1

Mild stomach problems were reported in one trial, in women only, and generally faded with time. The other trials in the same review reported no side effects or did not say.6

In a 107-day trial at 0.5 to 1 g a day, digestive symptoms were no more common than with placebo, and no serious adverse events were reported.1

In the first low-dose trial, no one taking colostrum for 20 days reported important digestive side effects, while four of the eight on the whey placebo reported loose stools, bloating, nausea or poor appetite.2

These trials were small, and at least one author disclosed a payment from a colostrum maker. Reviewers note that side effects were poorly reported, so a quiet result tells us less than it seems to.1,5

Why might a milk product loosen the stool?

Colostrum contains lactose, about 2 to 3% of fresh colostrum against about 5% in mature milk.3

MedlinePlus explains that people who cannot digest lactose may feel sick to their stomach and get gas, diarrhea and swelling in the stomach after foods that contain it. Colostrum has less lactose than mature milk, which is not the same as none. A person with a milk allergy has a different problem, since colostrum keeps the proteins of cow's milk.3,4

Does the amount matter?

At about 120 g a day, the amount one heat study used, a reviewer estimated an extra 70 g of protein and 35 g of lactose a day and warned that this could upset the gut.5

No upper limit has been set for colostrum. Most trials used 10 to 20 g a day for up to 12 weeks, and a few used 60 g a day for 8 to 9 weeks. Reviewers describe it as generally well tolerated while noting that side effects were poorly reported.5,6,7,8

Could diarrhea mean something else?

It could. FDA's page on raw milk lists vomiting, diarrhea and abdominal pain among the symptoms of foodborne illness, and says anyone who becomes ill after raw milk or products made from it should see a health care professional. Colostrum straight from the cow is raw milk until someone pasteurizes it, so a product's processing is part of the picture.3,9

Who should ask their doctor about colostrum and stomach upset?

  • Anyone with a milk allergy should ask their doctor before using colostrum, because it is a milk product with milk proteins.3
  • Anyone who is lactose intolerant should ask their doctor, because colostrum contains lactose.3
  • Anyone whose diarrhea lasts, or comes with vomiting, fever or belly pain, should ask a doctor rather than put it down to the supplement, because FDA lists those among the symptoms of illness from unpasteurized milk.9
  • Anyone who takes prescription medicines can ask their pharmacist, because no official source documents interactions with colostrum, which is not the same as none existing.

Questions people ask

Does colostrum cause diarrhea?

It can for some people, usually early in use and fading after a few days. In one 20 day trial, loose stools were reported by the group on a whey placebo and not by the colostrum group. Ask your doctor if it lasts.1,2

Does colostrum cause bloating?

Bloating is among the side effects researchers describe for colostrum taken by mouth, usually early in use. Colostrum also contains lactose, which can cause bloating in people who cannot digest it.1,3

Does colostrum cause gas?

The trials we read do not list gas on its own, but MedlinePlus lists gas among the results of not digesting lactose, and colostrum contains lactose.3,4

Does colostrum cause constipation?

The trial reports and reviews we read list nausea, diarrhea, bloating and abdominal pain, and did not list constipation.1,6

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Sources

  1. Baśkiewicz-Hałasa M, Stachowska E, Grochans E, et al. Moderate Dose Bovine Colostrum Supplementation in Prevention of Upper Respiratory Tract Infections in Medical University Students: A Randomized, Triple Blind, Placebo-Controlled Trial. Nutrients. 2023;15(8):1925. Opened 2026-10-01.
  2. Hałasa M, Maciejewska D, Baśkiewicz-Hałasa M, et al. Oral Supplementation with Bovine Colostrum Decreases Intestinal Permeability and Stool Concentrations of Zonulin in Athletes. Nutrients. 2017;9(4):370. Opened 2026-10-01.
  3. Playford RJ, Weiser MJ. Bovine Colostrum: Its Constituents and Uses. Nutrients. 2021;13(1):265. Opened 2026-10-01.
  4. MedlinePlus. Lactose Intolerance (health topic summary from the National Institute of Diabetes and Digestive and Kidney Diseases). U.S. National Library of Medicine. Opened 2026-10-11.
  5. Davison G. The Use of Bovine Colostrum in Sport and Exercise. Nutrients. 2021;13(6):1789. Opened 2026-10-01.
  6. Jones AW, March DS, Curtis F, Bridle C. Bovine colostrum supplementation and upper respiratory symptoms during exercise training: a systematic review and meta-analysis of randomised controlled trials. BMC Sports Sci Med Rehabil. 2016;8:21. Opened 2026-10-01.
  7. Duff WR, Chilibeck PD, Rooke JJ, Kaviani M, Krentz JR, Haines DM. The effect of bovine colostrum supplementation in older adults during resistance training. Int J Sport Nutr Exerc Metab. 2014;24(3):276-285. Opened 2026-10-07.
  8. Brinkworth GD, Buckley JD, Bourdon PC, Gulbin JP, David A. Oral bovine colostrum supplementation enhances buffer capacity but not rowing performance in elite female rowers. Int J Sport Nutr Exerc Metab. 2002;12(3):349-365. Opened 2026-10-07.
  9. U.S. Food and Drug Administration. The Dangers of Raw Milk: Unpasteurized Milk Can Pose a Serious Health Risk. FDA consumer page. Opened 2026-10-07.

This page is information, not medical advice. Talk to your doctor or pharmacist about your own situation.