Most common side effects in the label
The label’s table pools two placebo-controlled trials of up to 72 weeks in adults with obesity or overweight. The label presents doses of the investigational trial formulation as equivalent Foundayo™ doses, which is why the 6, 12 and 36 mg arms in the publications appear here as 5.5, 9 and 17.2 mg [1].
In the pooled trials, digestive side effects were reported by 60–69% on Foundayo™ depending on the dose vs 37% on placebo; of those, 60% were mild, 36% moderate and 4% severe. Nausea, vomiting and diarrhea were more frequent during dose escalation and decreased over time, and 3–6% stopped because of digestive reactions vs 0.7% on placebo [1].
| Adverse reaction | Placebo (N=1,576) % | 5.5 mg (N=1,051) % | 9 mg (N=1,055) % | 17.2 mg (N=1,049) % |
|---|---|---|---|---|
| Nausea | 10 | 26 | 34 | 35 |
| Constipation | 9 | 20 | 27 | 24 |
| Diarrhea | 11 | 21 | 23 | 25 |
| Vomiting | 4 | 13 | 21 | 24 |
| Dyspepsia | 4 | 12 | 16 | 13 |
| Abdominal pain | 7 | 13 | 14 | 14 |
| Headache | 7 | 8 | 9 | 9 |
| Abdominal distension | 3 | 7 | 9 | 8 |
| Fatigue | 4 | 6 | 7 | 9 |
| Eructation (belching) | 1 | 6 | 8 | 8 |
| Gastroesophageal reflux disease | 2 | 6 | 6 | 7 |
| Flatulence | 2 | 5 | 6 | 6 |
| Hair loss | 2 | 4 | 4 | 5 |
A reaction makes it into the label table only when at least 5% of people taking the medicine reported it and placebo users reported it less often; the placebo column shows how often the same complaint was reported without the medicine. The label also says these rates cannot be compared directly with other medicines’ trials [1].
Serious side effects the label warns about
Foundayo™ carries a boxed warning, drawn from rodent studies, on thyroid C-cell tumors; whether this happens in humans is unknown, and the label rules it out if you or a close relative have had MTC, or if you have MEN 2. Section 6 lists [1]:
- Risk of thyroid C-cell tumors (the boxed warning)
- Acute pancreatitis
- Severe gastrointestinal adverse reactions
- Acute kidney injury due to fluid loss (volume depletion)
- Hypoglycemia (low blood sugar)
- Hypersensitivity (allergic) reactions
- Diabetic retinopathy complications in people with type 2 diabetes
- Acute gallbladder disease
- Food or liquid entering the lungs (pulmonary aspiration) under general anesthesia or deep sedation
What the ATTAIN-1 trial reported
In ATTAIN-1, published in NEJM in 2025 (3,127 adults, 72 weeks), adverse events led to stopping treatment in 5.3–10.3% of people in the orforglipron groups and 2.7% on placebo. The most common events were gastrointestinal and mostly mild to moderate; the authors described the profile as consistent with other GLP-1 receptor agonists [2].
What happens if I stop Foundayo™?
The label does not describe what happens to side effects or weight after stopping [1], and we did not find a published orforglipron withdrawal trial among the sources checked for this page.
Stopping, pausing or restarting is a decision to make with your prescriber.
Foundayo™, pregnancy and birth control
Because Foundayo™ slows stomach emptying, it can change how well swallowed medicines, including birth-control pills, are absorbed. For that reason it covers two windows, the first 30 days of treatment and the 30 days that follow every step up in dose: during each, it suggests either moving to a contraceptive that is not swallowed or using a barrier method on top of the pill. Patches, rings, injections and other non-oral hormonal methods are not expected to be affected [1]. It also says to stop Foundayo™ when a pregnancy is recognized [1].
Plans for pregnancy or breastfeeding are worth raising with your prescriber before they happen.
Should I mention Foundayo™ before surgery or sedation?
Yes, according to the label. It describes rare postmarketing reports of food or liquid getting into the lungs (pulmonary aspiration) under general anesthesia or deep sedation in people taking GLP-1 receptor agonists, even when they had followed fasting instructions. The label says the data are not enough to recommend whether to change fasting or pause the medicine, and asks patients to tell their healthcare providers before any planned surgery or procedure [1].
Can I drink alcohol while taking Foundayo™?
The Foundayo™ label does not mention drinking alcohol [1]. Two related facts come from general medical sources: heavy alcohol use is one of the most common causes of pancreatitis [3], which the label lists as a serious risk [1]; and drinking too much alcohol without enough food can cause low blood sugar in people with diabetes [4]. How alcohol fits with your treatment is a question for your prescriber.
Is hair loss listed for Foundayo™?
Yes: the label table lists hair loss in 4–5% on Foundayo™ vs 2% on placebo. It was more frequent in women (7% vs 3% on placebo) than in men (0.9% vs 0.7%) and was associated with weight reduction [1].
For background, MedlinePlus describes a usually temporary kind of shedding (telogen effluvium) that can follow major physical stress, illness, surgery or crash diets [7]. A dermatologist or your prescriber can look at the cause.
Is burping listed for Foundayo™?
The label lists belching (eructation) among the main table: 6–8% on Foundayo™ vs 1% on placebo [1]. It does not describe the smell, so “sulfur burps” as such are not a label term; if burping comes with heartburn, vomiting or stomach pain that will not go away, the table below says who to contact.
Foundayo™ is a trademark of Eli Lilly and Company. PepLabo is not affiliated with this company. This page is not medical advice; percentages come from clinical-trial tables in the label and do not predict what you will experience.
When to get help
| Sign | Who to contact | How fast | Source |
|---|---|---|---|
| Swelling of the lips, tongue, face or throat, struggling to breathe or swallow, fainting or a racing pulse | Emergency services. According to the guide, Foundayo™ should be stopped and urgent medical help sought. | Emergency | Foundayo™ Medication Guide [1]; MedlinePlus [6] |
| Belly pain that is severe and does not ease, whether or not you vomit; it can reach through to the back | Your healthcare provider right away; the guide says to stop taking Foundayo™. If you cannot reach them, urgent care. | Emergency | Foundayo™ Medication Guide [1]; NIDDK [3] |
| Ongoing nausea, vomiting or diarrhea, or dehydration signs such as feeling very thirsty, a dry mouth, urinating less than usual, dark urine or dizziness | Your healthcare provider, right away: fluid loss can lead to kidney problems. | Today | Foundayo™ Medication Guide [1]; MedlinePlus [5] |
| Pain in the upper stomach, fever, yellowing of the skin or eyes, or clay-colored stools | Your healthcare provider (gallbladder problems). | Today | Foundayo™ Medication Guide [1] |
| Shakiness, sweating, confusion, blurred vision or a fast heartbeat; the risk is higher alongside insulin or a sulfonylurea | Follow the low-blood-sugar plan from your healthcare provider; the guide asks you to discuss it before starting. | Today | Foundayo™ Medication Guide [1]; MedlinePlus [4] |
| A new neck lump or swelling, a hoarse voice, difficulty swallowing or breathlessness | Your healthcare provider (thyroid section of the guide). | Today | Foundayo™ Medication Guide [1] |
| Changes in vision during treatment | Your healthcare provider. | Today | Foundayo™ Medication Guide [1] |
| A planned surgery or a procedure with anesthesia or deep sedation | Tell every healthcare provider involved that you use this medicine, before the procedure. | At your next appointment | Foundayo™ Medication Guide [1] |
| Mild nausea, constipation, heartburn or other common side effects that you can manage | Mention them at your next appointment; a dated log helps. | At your next appointment | Common reactions: label section 6 [1] |
