Life on GLP-1, read closely

GLP-1 medications compared: side effects of every FDA-approved option

Wegovy, the Wegovy pill, Zepbound, Foundayo, Saxenda, Ozempic and Mounjaro, side by side. How each is taken, and how often the common side effects show up, straight from the labels.

Updated October 2026 · 11 sources cited

Quick answer

Are the side effects the same for every GLP-1? Mostly, yes. They all list the same main side effects (nausea, vomiting, diarrhea, constipation) and the same safety warnings. What differs is how often they happen: it depends on the drug, the dose, and how quickly the dose goes up.

Approved for weight management

Weight-loss GLP-1 medications

Percent of people in the main trials who reported each side effect at the doses studied. Placebo rates are shown so you can see how much is the medication.

Medication	How it’s taken	Nausea	Vomiting	Diarrhea	Constipation	Placebo (N / V / D / C)	Notes
Wegovysemaglutide · Novo Nordisk	Injection, once weekly	44%	24%	30%	24%	16 / 6 / 16 / 11%	2.4 mg dose. A higher 7.2 mg dose was approved in March 2026.
Wegovy pilloral semaglutide 25 mg · Novo Nordisk	Pill, once daily, on an empty stomach	See note	See note	See note	See note	n/a	Approved December 2025. In the OASIS 4 trial, 74% had a GI side effect vs 42% on placebo; nausea, vomiting and constipation were most common.
Zepboundtirzepatide (GIP + GLP-1) · Eli Lilly	Injection, once weekly	25–33%	8–12%	19–23%	12–17%	10 / 2 / 7 / 6%	Range covers the 5, 10 and 15 mg doses (SURMOUNT-1).
Foundayoorforglipron · Eli Lilly	Pill, once daily, with or without food	26–35%	13–24%	21–25%	20–27%	10 / 4 / 11 / 9%	Approved April 2026. First non-peptide GLP-1 pill. Range covers 5.5 to 17.2 mg.
Saxenda (and generic liraglutide)liraglutide 3 mg · Novo Nordisk; generic since 2025	Injection, once daily	39%	16%	21%	19%	14 / 4 / 10 / 9%	Older daily option. Injection-site reactions in 14%.

These numbers come from separate trials, not head-to-head comparisons, so they can’t rank one drug over another.

Approved for type 2 diabetes

Diabetes GLP-1 medications

Same medicine class, often at lower doses. Some are prescribed off-label for weight.

Medication	How it’s taken	Common side effects in the label
Ozempicsemaglutide	Injection, once weekly	Nausea 16–20%, diarrhea about 9% (0.5 to 1 mg).
Mounjarotirzepatide	Injection, once weekly	Nausea 12–18%, diarrhea 12–17%, vomiting 5–9%, constipation 6–7%.
Rybelsusoral semaglutide	Pill, once daily, on an empty stomach	Same class pattern: GI effects most common. See the label.
Trulicitydulaglutide	Injection, once weekly	Same class pattern: GI effects most common. See the label.
Victoza (and generic liraglutide)liraglutide	Injection, once daily	Same class pattern: GI effects most common. See the label.

What they share

Side effects common to every GLP-1

All of these medications slow how fast the stomach empties and turn down appetite. That is why the most common side effects are in the gut, and why they tend to show up after starting or raising a dose, then ease over time.

Nausea Vomiting Diarrhea and fluids Constipation Fullness and indigestion Fatigue Headache and dizziness Hair shedding

Safety warnings in the labels

Thyroid C-cell tumors: a boxed warning based on rodent studies. Not for people with a personal or family history of medullary thyroid cancer or MEN 2.
Pancreatitis: severe stomach pain that may spread to the back.
Gallbladder problems: more likely with fast weight loss.
Kidney injury from dehydration: usually after vomiting or diarrhea.
Low blood sugar: mainly when combined with insulin or a sulfonylurea.
Anesthesia: tell your care team before surgery or sedation, because food can stay in the stomach longer.

What differs

What actually changes from one GLP-1 to another

Dose and pace

Higher doses and faster dose increases bring more stomach side effects. Most labels raise the dose every 4 weeks for that reason.

Pill vs. injection

Injections can cause injection-site reactions. The Wegovy pill must be taken on an empty stomach; Foundayo can be taken with or without food.

Daily vs. weekly

Daily options (Saxenda, Foundayo, Wegovy pill) and weekly shots (Wegovy, Zepbound) differ in schedule, not in the type of side effects.

What about compounded semaglutide or tirzepatide?

Compounded versions are not FDA-approved, so the FDA has not reviewed them for safety, quality or effectiveness, and doses may not match the branded products. Ask your prescriber where your medication comes from.

Call your prescriber right away if

You can’t keep fluids down, or vomiting won’t stop
Severe stomach pain, which may spread to your back
Signs of dehydration: dizziness, very dark urine, very little urine
Yellowing skin or eyes, or pain in the upper right belly

Common questions

Do all GLP-1 medications have the same side effects?

Mostly the same kind, at different rates. Every GLP-1 medication lists stomach and gut effects as the most common side effects, and they share the same safety warnings. What changes is how often they show up, which depends on the drug, the dose and how fast the dose is raised.

Which GLP-1 has the fewest side effects?

There is no fair ranking from these numbers. Each rate comes from a different trial with different people and doses. Lower doses usually cause fewer side effects, and most stomach side effects happen while the dose is being raised. Your prescriber can help match a medication and pace to you.

Are GLP-1 pills easier on the stomach than injections?

Not necessarily. Pills avoid injection-site reactions, but the stomach side effects are similar. The Wegovy pill and Foundayo both list nausea, vomiting, diarrhea and constipation as common.

Is Zepbound different from Wegovy?

Zepbound (tirzepatide) acts on two hormone receptors, GIP and GLP-1. Wegovy (semaglutide) acts on GLP-1 only. Both list the same main side effects. Their label rates differ, but they come from separate trials.

Are compounded semaglutide or tirzepatide the same?

No. Compounded versions are not FDA-approved, so the FDA has not reviewed them for safety, quality or effectiveness. Dosing can also differ from the branded products. Talk to your prescriber about where your medication comes from.

When should I call my prescriber?

Call if you can’t keep fluids down, have severe stomach pain that may spread to your back, signs of dehydration, yellowing skin or eyes, or any symptom that feels severe or unusual.

Sources

Rates are from FDA prescribing information or the pivotal trial for each product, at the doses listed. Labels change; check Drugs@FDA for the latest version. This page is information, not medical advice.