If you’re taking or considering taking GLP-1 medications for weight loss, you may already be aware of the possible side effects like nausea and constipation. But let’s take a moment to look at the bigger picture—the overall gut-GLP-1 connection—and how GLP-1 medications may affect your digestive health.

Digesting Food: GLP-1’s Impact on Gut Motility

One of the main ways GLP-1 medications work is by slowing the rate at which your stomach empties into the small intestine. Because food stays in the stomach longer, you feel full faster and potentially eat less. 

However, this slowing action is also why you may feel nauseous or constipated. In addition to food emptying more slowly from the stomach, GLP-1 medications can also reduce the frequency of muscle contractions in the small intestine that are needed to move food through the digestive tract.¹

Even though this slowdown in gut motility is by design, it also may be the reason many people on GLP-1 medications experience some initial digestive disturbances and discomfort. 

If you experience mild to moderate digestive-related side effects from GLP-1 medication, some over-the-counter remedies you’ve likely been using on and off for years may help. For example, Fleet® Liquid Glycerin Suppository and Fleet® Stimulant Oral Laxative may provide relief from GLP-1 related constipation. 

Consult your doctor to make sure the remedy you choose fits your personal health needs or if you have severe or concerning symptoms. 

Digestive Health: GLP-1’s Impact on Gut Microbiota

Gut health relies on a mixture of bacteria, fungi, viruses, and other microorganisms living in your digestive tract that are unique to you. The food you eat, medications you take, and environmental exposures can all influence the balance of this ecosystem resulting in a positive or negative effect on your digestion, immune system, and more.

Obesity shifts the balance of gut microbiota in a harmful way, which can lead to more weight gain and changes in metabolism. This condition can also weaken the intestinal barrier allowing bacteria to enter the bloodstream and trigger inflammation throughout the body. What this means is being overweight can create a physical cycle of dysfunction that can increase cravings for unhealthy food and make it hard to lose weight and improve gut health.²

GLP-1 medications can promote a healthier balance in your gut, and have the potential to decrease harmful bacteria, increase beneficial bacteria, and reverse the unhealthy shifts caused by obesity.² 

Understanding Acute versus Chronic Constipation

In general, many people experience acute constipation due to a change in diet, medications, or lifestyle. Stools may become infrequent and harder to pass. You may have three or fewer bowel movements a week. With a little attention, the constipation can be short-lived and may leave almost as suddenly as it arrived. 

Having constipation as you adjust to a GLP-1 is an example of acute constipation. You may need to change your diet, drink more fluids, change your eating and exercise schedule, or try an easily found remedy like the Fleet® products mentioned above. Your doctor may want to temporarily lower the dose of your medication, as well, until your body adjusts. 

Chronic constipation is having constipation symptoms for three months or longer. But please don’t wait three months to take action, because the straining while trying to go could cause damage to sensitive tissue in and around your anus. And chronic constipation can be a sign of another health issue.

You may be able to find relief for chronic constipation on your own by making changes to your fluid and food intake, keeping easier digestion in mind. However, if you have constipation that lasts three weeks or longer, contact your doctor to be safe. 

¹ Bellavance, D., Chua, S. & Mashimo, H. Gastrointestinal Motility Effects of GLP-1 Receptor Agonists. Curr Gastroenterol Rep 27, 49 (2025). https://doi.org/10.1007/s11894-025-00995-3

² Singh K, Aulakh S K, Nijjar G, et al. (July 17, 2024) Rebalancing the Gut: Glucagon-Like Peptide-1 Agonists as a Strategy for Obesity and Metabolic Health. Cureus 16(7): e64738. doi:10.7759/cureus.64738