Scientific deep-dive
Foundayo (Orforglipron) Side Effects: Rates by Dose, Dropouts and Interactions
Foundayo's side effects are mostly digestive and rise with dose: nausea in 26% to 35% vs 10% on placebo, and 10% quit at the top dose. The FDA label's full table, when effects ease, serious risks, CYP3A4 interactions, and how it compares with the Wegovy pill and injections.
Part of Safety and side effects, separated from the headlines
Foundayo’s side effects are mostly digestive, and they rise with the dose. In the two trials behind its approval, nausea hit 26% of people on 5.5 mg, 34% on 9 mg and 35% on 17.2 mg, against 10% on placebo.[1] Vomiting climbed from 13% to 24%. One in ten people on the top dose quit because of a side effect, against 3% on placebo.[1] Most stomach trouble was mild or moderate and was worst while the dose was being raised.[1]
Foundayo side effects by dose
The label pools two 72-week placebo-controlled trials: one in adults without diabetes (ATTAIN-1) and one in adults with type 2 diabetes (ATTAIN-2). In all, 3,155 people took the drug.[1] The table lists every reaction that hit 5% or more of them and was more frequent on the drug than on placebo.
| Side effect | Placebo | 5.5 mg | 9 mg | 17.2 mg |
|---|---|---|---|---|
| Nausea | 10% | 26% | 34% | 35% |
| Constipation | 9% | 20% | 27% | 24% |
| Diarrhea | 11% | 21% | 23% | 25% |
| Vomiting | 4% | 13% | 21% | 24% |
| Indigestion (dyspepsia) | 4% | 12% | 16% | 13% |
| Abdominal pain | 7% | 13% | 14% | 14% |
| Headache | 7% | 8% | 9% | 9% |
| Bloating (abdominal distension) | 3% | 7% | 9% | 8% |
| Fatigue | 4% | 6% | 7% | 9% |
| Belching (eructation) | 1% | 6% | 8% | 8% |
| Acid reflux (GERD) | 2% | 6% | 6% | 7% |
| Flatulence | 2% | 5% | 6% | 6% |
| Hair loss | 2% | 4% | 4% | 5% |
Counting every kind of stomach or gut complaint, 60% on 5.5 mg, 68% on 9 mg and 69% on 17.2 mg reported at least one, against 37% on placebo. Among drug-treated people who had one, 60% rated it mild, 36% moderate and 4% severe.[1] Elsewhere the label puts severe digestive reactions at about 3% on orforglipron and 1% on placebo.[1]
The step from 5.5 mg to 9 mg is where vomiting and constipation jump. The step from 9 mg to 17.2 mg adds little to either. The label prints no figures for the 0.8, 2.5 or 14.5 mg tablets; the trials held people at only three target doses.[1]
When the side effects start and when they ease
The label says nausea, vomiting and diarrhea were most common during dose escalation and became less frequent over time.[1] ATTAIN-2 described the same pattern.[3] The slowing of the stomach that drives much of the nausea is strongest after the very first tablet and fades with continued use.[1]
| Step | Daily dose | Earliest move to the next step |
|---|---|---|
| 1 | 0.8 mg | After 30 days |
| 2 | 2.5 mg | After 30 days |
| 3 | 5.5 mg | After 30 days, if needed |
| 4 | 9 mg | After 30 days, if needed |
| 5 | 14.5 mg | After 30 days, if needed |
| 6 | 17.2 mg | Maximum dose |
- The climb is the tolerability tool. The label says the schedule exists to reduce the risk of digestive side effects. Above 5.5 mg, each step depends on response and tolerability, so staying on a lower dose is a standard option.[1]
- A missed week resets the ladder. Miss seven or more consecutive tablets and the label calls for restarting at a lower dose, not picking up at the old one.[1] Restarting at full strength invites the early nausea back.
- It clears in days, not weeks. Orforglipron’s half-life is about 29 to 49 hours, and steady blood levels arrive after roughly a week.[1] The Wegovy label estimates semaglutide lingers 5 to 7 weeks after the final 25 mg tablet.[10]
How many people stopped Foundayo because of side effects
Discontinuation is the hardest number in any side-effect record: it counts people for whom the effects outweighed the benefit. On Foundayo it rose with dose in the label’s pooled trials, and every trial found it higher than on placebo.
| Source | Population | Orforglipron | Placebo |
|---|---|---|---|
| FDA label, pooled trials (72 weeks) | Obesity, with or without type 2 diabetes | 6% (5.5 mg), 9% (9 mg), 10% (17.2 mg) | 3% |
| Label, same pool: stopped for a GI effect | Same | 3%, 6%, 6% | 0.7% |
| ATTAIN-1 (72 weeks) | Obesity without diabetes | 5.3% to 10.3% | 2.7% |
| ATTAIN-2 (72 weeks) | Obesity with type 2 diabetes | 6.1% to 9.9% | 4.1% |
| ACHIEVE-1 (40 weeks) | Early type 2 diabetes | 4.4% to 7.8% | 1.4% |
The label pool and the three trials agree.[1][2][3][5] Most of the people who quit did so over digestive symptoms.[1] In a diabetes trial against dapagliflozin, one in five stopped the top dose for any reason; that trial, and why the highest dose often adds side effects faster than benefit, is covered in the top dose keeps not being worth it. A second diabetes trial in which 36 mg did no better than 12 mg on blood sugar is in the dose that stopped helping.
Less common side effects in the label
Below the 5% line, the label reports several findings from the same pooled trials. Most are small in absolute terms, but a few matter for particular groups.
| Finding | Foundayo | Placebo |
|---|---|---|
| Fast heart rate (tachycardia) | 3% | 0.9% |
| Average change in heart rate | +4 to 5 beats per minute | +0.5 |
| Low blood pressure (hypotension) | 2% | 0.5% |
| Low blood pressure, on blood pressure drugs | 4% | — |
| Hair loss, women | 7% | 3% |
| Hair loss, men | 0.9% | 0.7% |
| Dizziness | 4% | 3% |
| Taste changes (dysgeusia) | 0.9% | 0.3% |
| Altered skin sensation (dysesthesia) | 1% at 17.2 mg, 0.3% at 9 mg, none at 5.5 mg | 0.1% |
| Allergic reactions, including anaphylaxis | 0.5% | 0.3% |
| Acute kidney injury | 0.2% | 0.05% |
- Heart rate. The rise of 4 to 5 beats per minute is larger than the label figures for the injections: 1 to 3 for Zepbound and 1 to 4 for Wegovy.[1][11][10] In the head-to-head ACHIEVE-3 trial, pulse rose 3.7 to 4.7 beats per minute on orforglipron and 1.0 to 1.5 on oral semaglutide.[6]
- Blood pressure. Weight loss lowers blood pressure, and among people on the drug, low blood pressure hit 4% of those already taking blood pressure medicine and 1% of those who were not.[1] Lightheadedness on standing is worth reporting.
- Hair loss tracked weight loss and was concentrated in women.[1]
- Dysesthesia, a burning or tingling skin sensation, was reported in 5% on the 25 mg Wegovy pill.[10] On Foundayo it was 1% at the top dose.[1]
- Pancreatic enzymes. Amylase rose 16% to 20% and lipase 26% to 31% on average, against 3% and 4% on placebo. The label says the meaning of these rises is unknown without symptoms of pancreatitis.[1]
Serious risks and warnings
Like every GLP-1 drug, Foundayo has a boxed warning about thyroid C-cell tumors. Its version has an unusual footnote: orforglipron does not act on the rodent receptor and caused no tumors in rats or mice, so the human question stays open.[1] The hub page reads that warning in full. It is ruled out for people with MEN 2, for people who have had medullary thyroid carcinoma or have it in the family, and for anyone who has had a serious allergic reaction to the drug.[1] The other warnings, with the trial figures behind them:
- Pancreatitis. Six adjudicated cases in six people on the drug (0.14 per 100 patient-years) against one placebo patient (0.04). Persistent severe belly pain, sometimes into the back, means stop the drug and get checked.[1] Class context is in GLP-1 pancreatitis and gallbladder risk.
- Gallbladder disease. Gallstones in 1% vs 0.7% on placebo, and acute gallbladder inflammation in 0.4% vs 0.3%. The label ties these events to weight loss.[1]
- Severe digestive reactions in about 3% vs 1%. Not recommended for people with severe gastroparesis.[1]
- Kidney injury from dehydration. Most reported cases followed nausea, vomiting or diarrhea. The label asks for kidney checks in people with those symptoms, especially early and after each dose increase.[1]
- Low blood sugar. In the diabetes trial, glucose under 54 mg/dL occurred in 2% on the drug vs 0.2% on placebo, and in 7% of those also taking a sulfonylurea.[1] The risk also rises with insulin.
- Diabetic eye disease. Rapid glucose improvement can temporarily worsen diabetic retinopathy; people with that history need monitoring.[1]
- Aspiration under anesthesia. Delayed stomach emptying can leave food in the stomach during sedation. Tell the surgical team you take it.[1]
- Pregnancy and breastfeeding. Stop on learning of a pregnancy. The label says Foundayo is not recommended while nursing.[1]
Because orforglipron is cleared by the liver, its liver safety was examined on its own. In a pooled analysis of seven Lilly-sponsored phase 3 trials covering 11,220 people, serious combined liver-test elevations occurred in 0.1% on orforglipron and 0.1% on comparators. Every drug-group case had another explanation, and none met the standard definition of drug-induced liver injury.[9] The label advises against Foundayo in severe liver impairment, where drug exposure was 4.6 times normal.[1]
Drug interactions: the part injections do not have
Orforglipron is a small molecule broken down mainly by the liver enzyme CYP3A4.[1] Medicines that inhibit CYP3A4 push Foundayo levels up, raising side-effect risk; medicines that induce it pull levels down. The label’s measured and modeled effects:
| Other drug | Effect | Label instruction |
|---|---|---|
| Clarithromycin (strong CYP3A4 inhibitor) | Orforglipron exposure up 3.5-fold | Foundayo capped at 9 mg with any strong CYP3A4 inhibitor |
| Ritonavir-type drugs (strong CYP3A4 plus OATP1B inhibitors) | Large rise expected | Avoid the combination |
| Cyclosporine (OATP1B inhibitor) | Exposure up 2.6-fold | — |
| Verapamil (moderate CYP3A4 inhibitor, modeled) | Exposure up 2-fold | — |
| Carbamazepine (strong CYP3A4 inducer) | Exposure down 82% | Avoid; Foundayo may not work |
| Efavirenz (moderate CYP3A4 inducer, modeled) | Exposure down 61% | Monitor response, raise the dose if needed |
| Simvastatin | Active form up 2- to 2.5-fold | Simvastatin no higher than 20 mg a day |
| Esomeprazole (acid reducer) | No effect | — |
| Oral birth control pills | Absorption may change | Use a non-pill method, or pair the pill with condoms, during the first 30 days and the 30 days after every dose increase |
In practice, a course of clarithromycin taken with 17.2 mg would raise orforglipron exposure about 3.5-fold, which is why the label caps the dose at 9 mg alongside such drugs. The contraception rule restarts at every step up, so on the standard schedule it covers at least the first three months, and longer for anyone who keeps climbing. The mechanism is in GLP-1s and hormonal birth control. Bring a full medication list, including over-the-counter and herbal products, to the prescriber before the first tablet.[1]
Foundayo vs the Wegovy pill and the injections
Each label reports its own trials, run in different people and years, so the figures below are indicative, not a ranking.[1] For the injections, the closest like-for-like figures are the rates of any digestive side effect and of quitting because of side effects.
| Drug | Any GI side effect vs placebo | Stopped for any side effect vs placebo | Stopped for a GI side effect vs placebo |
|---|---|---|---|
| Foundayo 17.2 mg (tablet, daily) | 69% vs 37% | 10% vs 3% | 6% vs 0.7% |
| Wegovy pill 25 mg (tablet, daily) | 74.0% vs 42.2% | 6.9% vs 5.9% | 3.4% vs 2% |
| Wegovy 2.4 mg (injection, weekly) | 73% vs 47% | 6.8% vs 3.2% | 4.3% vs 0.7% |
| Zepbound 15 mg (injection, weekly) | 56% vs 30% | 6.7% vs 3.4% | 4.3% vs 0.5% |
Sources: Foundayo,[1] Wegovy pill and injection,[10][12] Zepbound.[11] Raw GI rates run from 56% to 74%, but the placebo groups differ too, so the excess over placebo is the fairer read. Foundayo’s excess, 32 points, matches the Wegovy pill’s and tops the 26 points for each injection; how that pill compares with its own injection overall is in Wegovy pill vs injection. Its 10% top-dose dropout rate is the highest in the table. Nausea follows the same pattern: 35% vs 10% on Foundayo’s top dose, 44% vs 16% on the Wegovy injection, and 28% vs 8% on Zepbound 15 mg.[1][10][11]
Two studies go further than the labels, and both come from a company with a stake. ACHIEVE-3, a Lilly-funded trial, put orforglipron directly against oral semaglutide at 7 and 14 mg, its diabetes strengths, in type 2 diabetes. GI events hit 58% to 59% on orforglipron against 37% to 45% on semaglutide, and quitting for side effects ran 9% to 10% against 4% to 5%.[6] Details are in the first pill-versus-pill trial. A Novo Nordisk–authored indirect comparison of the obesity trials found higher odds of stopping on orforglipron 36 mg than on oral semaglutide 25 mg, both for any side effect (odds ratio 4.1) and for GI side effects (13.9), with wide confidence intervals.[13] No head-to-head obesity trial has reported. The Wegovy pill’s own record is on Wegovy pill side effects.
In the larger ACHIEVE-4 trial in type 2 diabetes, GI events were reported by 62.1% on orforglipron against 14.2% on insulin glargine. Low blood sugar was the reverse: 6.8% against 19.2%.[7]
Side effects after switching from an injection
ATTAIN-MAINTAIN moved people who had lost weight on tirzepatide (205) or semaglutide (171) injections onto orforglipron or placebo for a year. The most common adverse events were digestive and mostly mild to moderate.[4] The published abstract gives no rates, so whether switching causes more or less stomach upset than starting fresh is not established. Costs at each dose, for anyone weighing the switch, are on what Foundayo costs.
If side effects push you from a pill to an injection, or the other way, it is simpler when one prescriber can write both. Ro lists Foundayo beside Zepbound, Wegovy and compounded semaglutide. Alloy, a menopause care company, offers Foundayo, Zepbound, and Wegovy as a pen or a pill to women in midlife, while PrideRx sells only brand-name drugs, with Foundayo, the Wegovy pill and Zepbound fulfilled through LillyDirect and NovoCare. At Sesame Care, the provider you pick from its marketplace can prescribe Foundayo or the Wegovy, Ozempic and Zepbound injections, all brand-name and billed apart from its care subscription.
Because some people stop Foundayo for side effects, the billing terms deserve a look before the first tablet. Pallas Health bills Foundayo every 4 weeks and charges nothing until a clinician prescribes. PreventiveMD and Found bill a membership separately from the drug itself, and Näky adds a monthly membership to its brand-name pills. Immortals sells Foundayo as a three-month package paid up front, and its terms say all sales are final.
Frequently Asked Questions
References
- 1.Eli Lilly and Company FOUNDAYO (orforglipron) tablets: US Prescribing Information, Boxed Warning and Sections 2, 5, 6.1, 7, 8 and 12 DailyMed (FDA-approved labeling). 2026. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=8ac446c5-feba-474f-a103-23facb9b5c62
- 2.Wharton S, Aronne LJ, Stefanski A, et al.; ATTAIN-1 Trial Investigators Orforglipron, an Oral Small-Molecule GLP-1 Receptor Agonist for Obesity Treatment N Engl J Med. 2025. PMID: 40960239.
- 3.Horn DB, Ryan DH, Kis SG, et al.; ATTAIN-2 Trial Investigators Orforglipron, an oral small-molecule GLP-1 receptor agonist, for the treatment of obesity in people with type 2 diabetes (ATTAIN-2): a phase 3, double-blind, randomised, multicentre, placebo-controlled trial Lancet. 2025. PMID: 41275875.
- 4.Aronne LJ, Horn DB, le Roux CW, et al. Orforglipron for maintenance of body weight reduction: the double-blind, randomized phase 3b ATTAIN-MAINTAIN trial Nat Med. 2026. PMID: 42120723.
- 5.Rosenstock J, Hsia S, Nevarez Ruiz L, et al.; ACHIEVE-1 Trial Investigators Orforglipron, an Oral Small-Molecule GLP-1 Receptor Agonist, in Early Type 2 Diabetes N Engl J Med. 2025. PMID: 40544435.
- 6.Rosenstock J, Yabe D, Cox D, et al.; ACHIEVE-3 Investigators Efficacy and safety of once-daily oral orforglipron compared with oral semaglutide in adults with type 2 diabetes (ACHIEVE-3): a multinational, multicentre, non-inferiority, open-label, randomised, phase 3 trial Lancet. 2026. PMID: 41765029.
- 7.Klein KR, Wysham C, Tuttle KR, et al. Cardiovascular safety of orforglipron versus insulin glargine in adults with type 2 diabetes at increased cardiovascular risk (ACHIEVE-4): a phase 3, event-driven, randomised, open-label, non-inferiority, active comparator trial Lancet. 2026. PMID: 42815506.
- 8.Ma X, Li YG, Raha S, et al. Pharmacokinetic Bioequivalence of Orforglipron Tablets and Capsules in Healthy Participants With Obesity or Overweight Diabetes Obes Metab. 2026. PMID: 41994902.
- 9.Wharton S, Stefanski A, Chen J, et al. Hepatic Safety of Orforglipron in Adults With Obesity or Overweight and/or Type 2 Diabetes: A Pooled Analysis of the Orforglipron Phase 3 Clinical Trials Diabetes Obes Metab. 2026. PMID: 42338042.
- 10.Novo Nordisk Inc. WEGOVY (semaglutide) injection and WEGOVY (semaglutide) tablets: US Prescribing Information (revised June 2026), Sections 5, 6.1 and 12.3 DailyMed (FDA-approved labeling). 2026. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=ee06186f-2aa3-4990-a760-757579d8f77b
- 11.Eli Lilly and Company ZEPBOUND (tirzepatide) injection: US Prescribing Information, Sections 5 and 6.1 DailyMed (FDA-approved labeling). 2026. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=487cd7e7-434c-4925-99fa-aa80b1cc776b
- 12.Wharton S, Lingvay I, Bogdanski P, et al.; OASIS 4 Study Group Oral Semaglutide at a Dose of 25 mg in Adults with Overweight or Obesity N Engl J Med. 2025. PMID: 40934115.
- 13.Michalak W, Bøg M, Bendixen T, et al. Oral Semaglutide 25 mg Versus Orforglipron 36 mg in Obesity: A Population-Adjusted Indirect Treatment Comparison Diabetes Obes Metab. 2026. PMID: 42225305.
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