Side effects
When to call your doctor on Foundayo
The Medication Guide names the moments. Severe stomach pain that will not go away, sometimes felt through to the back: stop and call right away. Stomach problems that are severe or do not go away: tell your provider. Nausea, vomiting or diarrhea that does not stop: fluids and a call. Upper stomach pain, yellow skin, fever, clay colored stools: call. A lump in the neck, hoarseness, trouble swallowing: call. Swelling of the face, trouble breathing, a severe rash: stop and get help.
DM, the one who read the label
Sources checked Oct 7, 2026
Published Oct 26, 2026
Updated Oct 7, 2026 · 2 min read
The short answer
The Medication Guide names the moments. Severe stomach pain that will not go away, sometimes felt through to the back: stop and call right away. Stomach problems that are severe or do not go away: tell your provider. Nausea, vomiting or diarrhea that does not stop: fluids and a call. Upper stomach pain, yellow skin, fever, clay colored stools: call. A lump in the neck, hoarseness, trouble swallowing: call. Swelling of the face, trouble breathing, a severe rash: stop and get help.
What the Medication Guide says
Every Foundayo bottle comes with a Medication Guide, and its list of serious side effects is the one to keep. These are its words, shortened only where it repeats itself.
Possible thyroid tumors. Tell your healthcare provider if you get a lump or swelling in your neck, hoarseness, trouble swallowing, or shortness of breath. Do not take Foundayo if you or your family have had medullary thyroid carcinoma or MEN 2.
Pancreatitis. Stop taking Foundayo and call your healthcare provider right away if you have severe pain in your stomach area that will not go away, with or without nausea or vomiting. Sometimes the pain is felt from the abdomen to the back.
Severe stomach problems. Tell your healthcare provider if you have stomach problems that are severe or will not go away.
Dehydration leading to kidney problems. Diarrhea, nausea and vomiting can cause a loss of fluids, which can cause kidney problems. Drink fluids. Tell your provider right away if nausea, vomiting or diarrhea does not go away.
Low blood sugar, especially with insulin or a sulfonylurea. Signs: dizziness, blurred vision, anxiety or mood changes, sweating, slurred speech, hunger, confusion, shakiness, weakness, headache, fast heartbeat, feeling jittery.
Serious allergic reactions. Stop and get medical help right away for swelling of the face, lips, tongue or throat, fainting or dizziness, problems breathing or swallowing, a very rapid heartbeat, a severe rash or itching.
Changes in vision, for people with type 2 diabetes: tell your provider.
Gallbladder problems. Pain in the upper stomach, yellowing of skin or eyes, fever, clay colored stools: tell your provider right away.
Food or liquid getting into the lungs during surgery or procedures with anesthesia or deep sedation: tell all your healthcare providers that you are taking Foundayo before a procedure.
What this page is not
A way to decide whether a symptom is serious. The guide's rule is simpler: the symptoms above are calls, and a doubt is a call. If you think you have an emergency, call your local emergency number.
What people actually do
The forums hold ordinary side effects and few serious ones, which is as it should be. What people describe struggling with is the line between a bad stomach week and the guide's warnings, and the guide draws it for them: pain that stays and reaches the back, vomiting that does not stop, the four gallbladder signs.
The surgery line is the one people most often have not read, and it is the one that matters on the morning of a procedure.
Oolite prints the guide's list in the app, word for word, and keeps a dated journal so that a symptom that is getting worse over days is visible as a line. It never judges a symptom; the number to call is the prescriber's.
Questions people ask
How do I tell everyday nausea from the pancreatitis warning?
The guide describes pancreatitis as severe pain in the stomach area that will not go away, with or without nausea or vomiting, sometimes felt from the abdomen to the back. Everyday nausea comes and goes and has no such pain. In doubt, the guide's answer is to stop and call.
What are the gallbladder signs?
Pain in the upper stomach, yellowing of the skin or eyes, fever, clay colored stools. The guide says to tell your provider right away.
What does the guide say about surgery?
That Foundayo may increase the chance of food getting into the lungs during surgery or procedures with anesthesia or deep sedation, and that you should tell all your healthcare providers you are taking it before a procedure.
What about my eyes?
The guide asks people with type 2 diabetes to tell their provider about changes in vision during treatment.
Sources
- Foundayo Medication Guide, Eli Lilly, issued 07/2026 · Serious side effects: thyroid tumors, pancreatitis, severe stomach problems, dehydration leading to kidney problems, low blood sugar, serious allergic reactions, vision changes in type 2 diabetes, gallbladder problems, aspiration during anesthesia.
Sources checked Oct 7, 2026. This page is information, not medical advice: read the medical disclaimer, and talk to your prescriber or pharmacist about your own treatment.
Written by
DM, the one who read the label
I make Oolite. I read every label revision the day it comes out and rewrite these answers when they change.
How these pages are madeOolite
The GLP-1 tracker for the pill and the shot.
The 30 minute timer, your shot day, the level chart and the dose reminder, on iPhone, with Apple Watch to log. Free to download, then a 14-day free trial.
