Man stepping on bathroom scale wondering about Ozempic and diarrhea side effect

Ozempic® and Diarrhea: What to Know

Written on October 30, 2023 by Lori Mulligan, MPH. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

Table of contents

Ozempic®, whose active ingredient is semaglutide, is a glucagon-like peptide-1 (GLP-1) receptor agonist (RA) labeled for the treatment of type 2 diabetes mellitus in adults.[1]

Ozempic® is available as a liquid that comes in a prefilled pen. It is injected once weekly under the skin of the abdomen, thigh, buttocks, or upper arm. Ozempic® may be used alone or in combination with other FDA-approved diabetes medications such as metformin, sulfonylureas, thiazolidinedione, and insulin.[2]

In addition to treating diabetes, Ozempic® has received a lot of attention as a miracle drug for weight loss. However, many doctors are now cautioning that it is not the magic bullet that it has been hyped up to be. This is because of the side effects, such as diarrhea, loss of appetite, nausea, stomach pain, and vomiting. Other, more serious side effects include allergic reactions, changes in vision, dehydration, gallbladder problems, heart palpitations, kidney injury, pancreatitis, and thyroid cancer.[3]

Let’s consider the unpleasant side effect of diarrhea from Ozempic® that affects a large percentage of people taking the drug.

The exact reason for diarrhea is unclear, but it is assumed to result from the way Ozempic® influences the absorption of nutrients and gut transit time. If certain nutrients are not absorbed, this can lead to diarrhea due to increased water moving into the bowels, a phenomenon known as osmotic diarrhea. On the other hand, malabsorption of nutrients because of slowed gastric motility due to Ozempic® can also cause diarrhea.

The slowing of bowel motility influences diarrhea while on Ozempic®. The stretching of the stomach is known to cause a reflex known as the gastrocolic reflex, which impacts the movement of the muscles in the colon. The prolonged stretch of the stomach due to Ozempic® can cause the activation of this reflex, leading to increased motility in the lower gastrointestinal tract and causing diarrhea.

Research has demonstrated around 32% of people taking Ozempic® for weight loss experience diarrhea.[4]

Research Supports Adverse Gastrointestinal (GI) Events from Semaglutide

In a review article published in Frontiers in Endocrinology, the authors summarize previous research on adverse GI complaints from semaglutide. They found that GI complaints are the main adverse-event-related cause of drug discontinuation in phase-3 trials, with rates up to 12%. In one retrospective study comprising 189 patients with type 2 diabetes who started injectable semaglutide, 9.5% discontinued therapy because of GI complaints. In an additional 5.8% of patients, such adverse effects limited dose escalation.

In another cohort where 164 type 2 diabetes patients were switched from a different GLP-1RA therapy to semaglutide, 10.4% discontinued semaglutide because of adverse GI effects. Combined, data from clinical trials and clinical practice suggest that approximately 10% of patients will discontinue semaglutide because of GI complaints, which may be a bit higher compared to other GLP-1 analogues.

Apart from gradual dosing, data on how to prevent or treat GI disturbances with GLP-1RA are limited. Patients can be advised to eat slowly with reduced portion size per meal, stop eating when they are full, and avoid high-fat food.

The mechanisms behind diarrhea are not completely understood, as studies are lacking. In one study, osmotic diarrhea occurred eight hours after injection of GLP-1. Additionally, GLP-1RAs have been shown to reduce intestinal uptake of glucose and lipids. Semaglutide could induce diarrhea by altering nutrient absorption or intestinal motility.[5]

As reported in Nature Medicine, gastrointestinal disorders, namely nausea, diarrhea, vomiting, and constipation, were the most frequently reported adverse events and occurred in more participants treated with semaglutide than with placebo (82.2% versus 53.9%, respectively). Most GI adverse events were mild-to-moderate and transient but did lead to permanent treatment discontinuation in six (3.9%) participants in the semaglutide group and one (0.7%) participant in the placebo group.[6]

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The home-collection hemoglobin A1c test is an easy way to measure how well you have been maintaining your blood sugar levels for the past 90 days. Routine monitoring with HbA1c testing is important for individuals who have been diagnosed with prediabetes, diabetes, or gestational diabetes.

HbA1c is a measurement of the amount of glucose bound to the heme found in red blood cells. Blood glucose (commonly referred to as blood sugar) levels tested as a single measurement can vary significantly throughout the day based on many factors, including a recent meal or physical activity. An A1c test measures your average blood sugar over a span of 2-3 months. This test is used by healthcare providers to help diagnose conditions that result in too much sugar in the blood, such as diabetes, prediabetes, and gestational diabetes. If you have prediabetes, diabetes, or other related conditions, this test can tell how well your treatment may be working for you.

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Ozempic® Nausea Relief: What to Know

Can You Drink Alcohol While Taking Ozempic® for Weight Loss?

Can You Take Ozempic® While Pregnant?


  1. Semaglutide (Ozempic®) for type 2 diabetes mellitus. American Family Physician. Accessed on 10/10/2023.
  2. Drug trial snapshot: Ozempic®. Food and Drug Administration. 8/20/2020. Accessed on 10/10/2023.
  3. Semaglutide injection. Cleveland Clinic. Accessed on 10/10/2023.
  4. Possible Side Effects of Ozempic® (semaglutide) Injection. Novo Nordisk. Accessed on 10/10/2023.
  5. Smits MM, Van Raalte, DH. Safety of semaglutide. Front. Endocrinol., 07 July 2021. Sec. Clinical Diabetes Volume 12 - 2021.
  6. Garvey, W.T., Batterham, R.L., Bhatta, M. et al. Two-year effects of semaglutide in adults with overweight or obesity: the STEP 5 trial. Nat Med 28, 2083–2091 (2022).
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