Diarrhea on a GLP-1: what to eat, what to drink and when to call

How common is diarrhea on a GLP-1?

Common enough that it's printed near the top of every label. The FDA-approved Wegovy label lists nausea, diarrhea, vomiting, constipation and stomach pain among the most common side effects. In the Wegovy injection trials for weight reduction, 30% of people on Wegovy reported diarrhea, compared with 16% on placebo.

The Zepbound label shows a similar picture: diarrhea was reported by about one in five people on Zepbound in its weight trials, compared with 8% on placebo. The label adds that most nausea, vomiting and diarrhea happened while the dose was being raised and decreased over time.

MedlinePlus lists diarrhea among the side effects of both semaglutide and tirzepatide, and says to tell your doctor if it's severe or doesn't go away.

So diarrhea on a GLP-1 is usually expected and usually temporary. It still deserves attention, because the main risk isn't the loose stools themselves. It's the fluid you lose.

Why fluids come first

Both labels carry a warning about acute kidney injury tied to dehydration. The Wegovy label says there have been reports of kidney injury, in some cases needing dialysis, in people whose nausea, vomiting or diarrhea led to dehydration. Its patient information puts it plainly: it's important to drink fluids to lower your chance of dehydration, and to tell your provider right away if nausea, vomiting or diarrhea doesn't go away.

The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) says that when you have diarrhea you need to replace lost fluids and electrolytes. It suggests:

• Water, plus drinks that contain electrolytes, such as broths and sports drinks.
• Oral rehydration solutions, which contain glucose and electrolytes. You can buy them at most pharmacies.

NIDDK adds that older adults and people with diabetes, kidney disease or a weak immune system should check with their doctor before using oral rehydration solutions, since a specific product or amount may suit them better. That matters here, because many people on a GLP-1 have diabetes.

MedlinePlus suggests drinking at least 1 cup of liquid every time you have a loose bowel movement, and says water is best. If your appetite is low on the medicine, sipping steadily through the day is easier than trying to drink a lot at once.

What to eat when you have diarrhea on a GLP-1

You don't need a special diet. NIDDK says most experts don't recommend a restricted diet or fasting for diarrhea, and that once your appetite returns you can usually go back to your normal diet, even if the diarrhea hasn't fully stopped.

What helps is choosing foods that are gentle and easy to digest. MedlinePlus suggests:

• Small meals through the day instead of three large ones. This also suits the smaller appetite many people have on a GLP-1.
• Lean protein that's baked or broiled, such as chicken, turkey, fish, beef or pork, and cooked eggs.
• Refined grains, such as white rice, pasta, white bread, cream of wheat, oatmeal and cornflakes.
• Cooked vegetables like carrots, green beans, squash and peeled zucchini, and baked potatoes. Removing seeds and skins helps.
• Some salty foods, such as pretzels or soup, to help replace sodium.
• Some high-potassium foods, such as bananas and potatoes. If you have significant kidney disease, check with your provider first.
• Low-fat milk, cheese or yogurt, unless dairy seems to make things worse.

Protein still matters on a GLP-1, even on a rough day. Our guide to getting enough protein on a GLP-1 has ideas that are easy on the stomach, like eggs and yogurt.

If you're having trouble keeping track of what you've eaten and drunk on a bad day, a health companion app can help. Olive checks in with you every day, looks at what you eat, and helps you build small habits that actually hold. It doesn't diagnose or treat anything, so ongoing side effects are still a question for your prescriber.

What to avoid for now

NIDDK and MedlinePlus point to the same short list of foods and drinks that can make diarrhea worse:

Sugar alcohols deserve a special mention. NIDDK's examples are sugarless gum and candies, but many "sugar-free" snacks use them too. If your diarrhea started around the same time as a new sugar-free product, check the ingredient list.

NIDDK notes that trouble digesting lactose after diarrhea can last up to a month or more, so a slow return to dairy is reasonable.

When diarrhea on a GLP-1 needs a call

NIDDK lists warning signs that mean you should see a doctor right away. These include:

• Signs of dehydration: extreme thirst, dry mouth, urinating less than usual, dark urine, feeling tired or dizzy, sunken eyes, or skin that doesn't flatten back when pinched.
• Diarrhea lasting more than 2 days.
• Six or more loose stools in a day.
• Severe pain in the belly.
• Black, tarry or bloody stools.
• A high fever, frequent vomiting, or a change in mental state such as confusion.

NIDDK also says people who are pregnant, over 65, taking antibiotics or living with a weakened immune system are more likely to have health problems from diarrhea and should keep in touch with their doctor.

MedlinePlus adds a few more: blood or mucus in the stool, a fever that doesn't go away, and stomach pain that won't go away.

On a GLP-1, there's one more reason to call: the label warnings. MedlinePlus says to get medical help right away for ongoing pain that begins in the upper left or middle of the stomach but may spread to the back, with or without vomiting. Diarrhea that keeps you from drinking enough is also worth a call, because of the kidney warning above. Your prescriber may want to adjust how you're taking the medicine. Don't change your dose or skip doses on your own.

If nausea is the bigger problem for you, our guide to eating with GLP-1 nausea covers that side.

A simple plan for a bad day

• Morning: Start with water or broth. If you're hungry, try toast, oatmeal or a cooked egg.
• Through the day: Sip something after every loose stool. Eat a small plain meal every few hours instead of one big one.
• Evening: Keep dinner simple: baked chicken or fish, white rice or a baked potato, and a cooked vegetable.
• Skip: Coffee, alcohol, fizzy drinks, fried food and sugar-free sweets.
• Watch: How often you're urinating and what color it is. Less often or darker means you need more fluid.

If diarrhea keeps coming back week after week, keep a simple log of what you ate and when symptoms started. NIDDK suggests a food diary for chronic diarrhea, and it gives your prescriber something real to look at. Longer-term eating changes can also affect your nutrients, which our guide to nutrient gaps on a GLP-1 covers.

This guide is general information, not medical advice. Talk with your prescriber about side effects, and don't start, stop or change any medicine without them.

Steady meals, even on rough days

Getting through side effects is easier when meals and fluids stay steady. Olive checks in with you every day and notices what's keeping your body stuck.

If steady habits haven't moved stubborn weight, Olive's Protocol is one option to look into. Prescriptions are only written after a medical consultation with a licensed provider. Not everyone qualifies.

See how Olive works →