Orforglipron Side Effects, From the Label Itself
Foundayo is new enough that most of what is written about its side effects is guesswork from the drug class. It does not need to be. The approved label reports every reaction seen in 5% or more of patients, broken down by dose.
- 69%Had a gastrointestinal reaction at the top dose, against 37% on placebo
- 8%Stopped taking it because of side effects, against 3% on placebo
- 4%Of those reactions were severe — 60% were mild
- 3,155Adults in the safety population, followed for up to 72 weeks
The short version
The side effects are overwhelmingly digestive, they get more common as the dose rises, and they are worst while the dose is being increased. Nausea is the most reported, at roughly a third of people on the highest dose against one in ten on placebo.
Two things are worth holding alongside those numbers. The placebo column is not zero — one in ten people reported nausea without taking the drug at all, so the drug’s contribution is the gap, not the whole figure. And the great majority of reactions were graded mild or moderate: severe ones were 4% of those reported.
This page reports what the label reports. It is not a guide to managing side effects, and nothing here is a reason to change how you take a prescribed medicine. Background on the drug itself is on our orforglipron index.
Every side effect reported in 5% or more of patients
Pooled from the two placebo-controlled weight-management trials, in patients with and without type 2 diabetes. Figures are the percentage of each group reporting that reaction. Read across the row to see how it scales with dose, and compare every figure against the placebo column.
| Reaction | Placebo | 5.5 mg | 9 mg | 17.2 mg |
|---|---|---|---|---|
| Nausea | 10% | 26% | 34% | 35% |
| Constipation | 9% | 20% | 27% | 24% |
| Diarrhoea | 11% | 21% | 23% | 25% |
| Vomiting | 4% | 13% | 21% | 24% |
| Indigestion | 4% | 12% | 16% | 13% |
| Abdominal pain | 7% | 13% | 14% | 14% |
| Headache | 7% | 8% | 9% | 9% |
| Abdominal bloating | 3% | 7% | 9% | 8% |
| Fatigue | 4% | 6% | 7% | 9% |
| Burping | 1% | 6% | 8% | 8% |
| Acid reflux | 2% | 6% | 6% | 7% |
| Flatulence | 2% | 5% | 6% | 6% |
| Hair loss | 2% | 4% | 4% | 5% |
Note that headache barely separates from placebo at any dose, and several reactions do not rise between 9 mg and 17.2 mg — constipation and indigestion are actually reported slightly less often at the top dose. The dose-response is real for nausea and vomiting; it is not uniform across everything.
The digestive effects, and when they happen
Taken as a group rather than symptom by symptom, gastrointestinal reactions were reported by 60% of people on the lowest studied dose, 68% at the middle dose and 69% at the highest — against 37% on placebo. That is the headline risk of this drug, and the number most worth knowing before starting it.
It is worst early, not throughout
The label states that nausea, vomiting and diarrhoea were more common while the dose was being increased, and decreased over time. That matters for anyone reading the table above and assuming those percentages describe every week of treatment. They describe a period, concentrated at the start.
Severity is reported too, and it is the part usually left out. Of the people who had a gastrointestinal reaction, 60% were mild, 36% moderate and 4% severe. Digestive reactions were also the main reason people stopped: 3% at the lowest dose through 6% at the top, against 0.7% on placebo.
How many people stopped because of it
Across both trials, 8% of people taking Foundayo stopped permanently because of an adverse reaction, against 3% on placebo. That figure climbs with dose, and the climb is the useful part.
| Group | Stopped because of a side effect |
|---|---|
| Placebo | 3% |
| 5.5 mg | 6% |
| 9 mg | 9% |
| 17.2 mg | 10% |
One in ten people on the highest dose stopped taking it. That is worth setting beside the weight results from the same trials, where the highest dose also produced the largest reduction — the dose that works best is also the one people are most likely to abandon. Neither figure is meaningful without the other.
The serious warnings on the label
Separate from the common reactions above, the label carries a set of warnings about rarer but more serious events. These are not things most people will experience; they are things a prescriber weighs before prescribing, and worth recognising.
- Thyroid C-cell tumours — the boxed warning. Carried across this whole drug class. Uniquely, orforglipron’s label records that it produced no tumours in rodents and is not pharmacologically active in them; the warning is retained because human relevance is undetermined. It is contraindicated for anyone with a personal or family history of medullary thyroid carcinoma, or with MEN 2.
- Pancreatitis, gallbladder disease and severe gastrointestinal reactions. All three appear as distinct warnings. Persistent severe abdominal pain is the symptom the label flags for urgent attention.
- Kidney injury from dehydration. A consequence of the vomiting and diarrhoea rather than a direct effect — which is why the fluid loss is treated as serious rather than merely unpleasant.
- Low blood sugar. In the diabetes trial, hypoglycaemia was reported by 2% on the drug against 0.2% on placebo, with one severe case. The risk is materially higher for anyone also taking insulin or a sulfonylurea.
- Diabetic retinopathy complications, hypersensitivity reactions, and aspiration under anaesthesia. The last is why the label tells patients to mention this drug to anyone planning surgery or a procedure involving sedation.
Interactions, which are unusual for this class
This is where being a small molecule rather than a peptide changes things. Orforglipron is processed by the liver enzyme CYP3A4, which the injected peptides in this class are not — so it has drug interactions they do not have.
- Drugs that inhibit CYP3A4 raise its levels in the blood, which raises the chance of the side effects above. The label restricts the maximum dose when it is taken with a strong inhibitor, and tells prescribers to avoid combining it with inhibitors that also block a transporter called OATP1B — ritonavir is the example given.
- Drugs that induce CYP3A4 lower its levels, which may make it less effective. Strong inducers are to be avoided; with moderate ones the label tells prescribers to monitor whether it is still working.
- Simvastatin. Taking the two together doubled exposure to simvastatin’s active form, so the label sets a ceiling on the simvastatin dose. A common enough combination — a statin and a weight-management drug — that it is worth raising directly with a prescriber.
- Insulin and sulfonylureas. Combining them raises the risk of low blood sugar, and the label directs prescribers to manage that when starting treatment.
Why we have not printed the numbers
The label gives specific dose limits for these interactions. We have described what the limits do rather than reproducing them, because a dose ceiling published on a web page functions as an instruction however it is framed — and the person applying it needs to know your full medication list, which we do not. Take the list above to whoever prescribes for you.
What this site will not tell you
- How to reduce or manage these side effects. That is a conversation with a prescriber who knows your history, not a web page.
- Whether to lower your dose, pause, or stop. Nothing on this page is a reason to change a prescribed medicine without medical advice.
- The specific dose limits attached to the interactions above, for the reason given in that section.
- Anything about side effects of compounded or unapproved orforglipron. There is no approved generic, concentrations in compounded products vary, and figures from this label do not transfer to them.
Sources and method
- Every figure on this page. The approved prescribing information for Foundayo (orforglipron), NDA 220934, read in full from the FDA’s own document archive — the adverse reactions section for the incidence table, discontinuation rates and severity split, the warnings section for the serious events, and the drug interactions section.
- The safety population. 3,155 adults with obesity or overweight treated for up to 72 weeks across the two placebo-controlled trials, pooled. Mean age 49, 41% male, 31% with type 2 diabetes, mean BMI 36.5. Percentages describe that population and may not describe yours.
- What we could not verify. Anything about long-term use beyond 72 weeks, since the trials did not run longer. Postmarketing reports are still accumulating for a drug approved in 2026, so the picture here reflects trial experience rather than years of real-world use — and rare effects generally surface after approval, not before.
- Method. Every percentage is reproduced with its placebo comparison, because a side-effect rate without one is uninterpretable. Severity and timing are reported alongside incidence for the same reason. Where the label gives a numeric dose instruction, we describe its effect rather than reprint it.
Orforglipron index → GLP-1 medications → How we source and verify →
FDA label read 5 September 2026. We recheck this page whenever the label is revised, which for a newly approved drug can happen at short notice.