Orforglipron

Mechanism and effects

Orforglipron activates the GLP-1 receptor, helping regulate appetite and blood sugar. It is a small molecule rather than a peptide. Foundayo is the approved tablet.^538,539

Where it is approved

The US label covers long-term weight management in adults with obesity, or overweight with a weight-related condition. The UK also authorized it for type 2 diabetes in August 2026. Both approvals are for adults.^538,540

The pill and the trial capsule

Many papers report a 36 mg capsule. The corresponding marketed tablet is 17.2 mg. A study of 429 adults showed comparable drug exposure across six capsule/tablet pairs. The formulations have different strengths and absorption.^541,542

Food and water

The current tablet label allows use with or without food. Two small studies found that meals reduced drug exposure modestly; the authors judged the difference unlikely to affect clinical benefit.^538,543

Weight loss in the main trials

The pivotal weight trials lasted 72 weeks.

Without T2D		11.1%
Placebo (T1)		2.1%
With T2D		9.6%
Placebo (T2)		2.5%

Percentage of starting body weight. Trial 1 enrolled 3,127 adults without diabetes; Trial 2 enrolled 1,613 with type 2 diabetes. Active bars show the highest tablet-equivalent dose, 17.2 mg. These are the US label treatment-regimen estimates. All groups received lifestyle support.

Treatment-regimen and efficacy estimates

A treatment-regimen estimate includes people who stopped treatment or had other treatment changes. An efficacy estimate asks how the medicine performs if people remain on treatment under the study conditions. The published ATTAIN-1 treatment-regimen result was 11.2% at the highest capsule dose; the current label reports 11.1%. Keep each figure attached to its source.^545,538

How many lost at least 15%?

In the highest-dose arm of the label trial without diabetes, 35.9% lost at least 15% of their starting weight, compared with 6.0% on placebo. In the trial with type 2 diabetes, the corresponding proportions were 25.9% and 3.1%.⁵⁴⁴

Staying on treatment

Across the active groups in ATTAIN-1, 5.3% to 10.3% stopped treatment because of adverse events, compared with 2.7% on placebo. Stomach and bowel symptoms were the main tolerability issue.⁵⁴⁵

How it compares

A trial compared the oral medicines directly; other analyses pooled results across trials and populations.

The direct oral-semaglutide trial

ACHIEVE-3 randomized 1,698 adults with type 2 diabetes taking metformin. At 52 weeks, the higher orforglipron dose lowered HbA1c by 1.91 percentage points, compared with 1.47 points for oral semaglutide 14 mg. The orforglipron dose was a 36 mg trial capsule, corresponding to a 17.2 mg tablet. The trial was open-label.^546,542

The tolerability trade-off

In those higher-dose groups, stomach and bowel events occurred in 58% with orforglipron and 45% with oral semaglutide. Adverse events led 10% and 5%, respectively, to stop treatment.⁵⁴⁶

Two indirect comparisons

A published analysis in adults without diabetes favored oral semaglutide 25 mg by 3.2 percentage points of weight loss. A September 29 manufacturer analysis in type 2 diabetes favored orforglipron by 1.5 points. Both combined results from separate trials, with different populations and statistical adjustments. A direct trial against oral semaglutide 25 mg would give a clearer comparison.^547,548

After injectable treatment

ATTAIN-MAINTAIN randomized 376 people previously treated with tirzepatide or semaglutide. Among those whose weight had plateaued, orforglipron preserved an estimated 74.7% of the earlier weight loss after tirzepatide and 79.3% after semaglutide at one year. Placebo preserved 49.2% and 37.6%. The trial compared a switch to orforglipron with placebo; nobody was assigned to continue the injectable.⁵⁴⁹

Stopping orforglipron

No cited completed adult trial was designed to follow weight after stopping orforglipron. The maintenance trial above studied the switch from injectable treatment.^549,550

Side effects and longer follow-up

Common symptoms are well described. Rare and long-term effects need continued follow-up.

Common side effects

At the highest tablet-equivalent dose in the pooled weight trials, nausea occurred in 35%, diarrhea in 25%, constipation in 24% and vomiting in 24%. Placebo rates were 10%, 11%, 9% and 4%. Symptoms were most frequent during dose increases.⁵⁴⁴

Important warnings

The US label warns about pancreatitis, severe stomach problems, dehydration-related kidney injury, gallbladder disease, serious allergic reactions and aspiration around anesthesia. People with type 2 diabetes also need attention to hypoglycemia and changes in diabetic retinopathy.⁵³⁸

Thyroid warning

The US label carries the GLP-1 class warning about thyroid C-cell tumors and excludes people with a personal or family history of medullary thyroid carcinoma or MEN2. Orforglipron itself is not pharmacologically active in ordinary rats or mice. Its early animal work used humanized receptors and nonhuman primates.^544,551

Liver findings

A pooled analysis included 11,220 phase III participants followed for up to 104 weeks, including safety follow-up. It found no orforglipron cases meeting the authors’ drug-induced liver injury/Hy’s law criteria after alternative causes were considered. The trials excluded some people with high liver-enzyme values before treatment.⁵⁵²

Cardiovascular follow-up

In the 2,749-person ACHIEVE-4 trial, Lilly reported that orforglipron met the prespecified cardiovascular noninferiority test against insulin glargine. The MACE-4 hazard ratio was 0.84, with a 95% confidence interval of 0.59 to 1.20. As of September 30, 2026, these results were available in a manufacturer report. The lower observed mortality came from an analysis without adjustment for multiple testing.^553,554

Japanese trial evidence

ACHIEVE-J followed 401 Japanese adults with type 2 diabetes for 52 weeks. Across three trial-capsule groups, 85% reported an adverse event, usually mild or moderate. Discontinuation due to adverse events ranged from 5% to 14%. This was an open-label comparison of doses.⁵⁵⁵

Interactions, pregnancy and evidence gaps

The current product label is the reference for treatment decisions.

Birth control

The US label recommends non-oral contraception or an added barrier method for 30 days after starting and after each dose increase. It gives this precaution because orforglipron delays stomach emptying. The effect on oral-contraceptive absorption has not been tested in a clinical trial.⁵⁴⁴

Other medicines

Strong CYP3A4 inhibitors, some OATP1B inhibitors, strong CYP3A4 inducers and simvastatin have specific label restrictions. A medication review should use the local product information, since US and UK instructions differ.^544,542,556

Pregnancy and breastfeeding

The US label says to stop when pregnancy is recognized and advises against breastfeeding during treatment. Human pregnancy data are inadequate. FDA required further pregnancy and milk-transfer studies.^538,557

Evidence gaps

Most clinical evidence comes from the manufacturer’s development program. Longer-term outcomes, pregnancy, breastfeeding, pediatric use and weight after stopping treatment are important gaps. Cited Chinese and Russian records mainly repeated Western trials or described planned research. Official Japanese and Indian records added trial details.^{557,558,559,560,561}

Common questions

Results, cost, practical choices and safety.

01 How does Foundayo compare with oral semaglutide or injectable GLP-1 medicines?

ACHIEVE-3 directly compared oral orforglipron with oral semaglutide in 1,698 adults with type 2 diabetes taking metformin. At 52 weeks, the 12 and 36 mg study capsules, equivalent to the 9 and 17.2 mg commercial tablets, lowered HbA1c more than oral semaglutide 7 and 14 mg. Two indirect comparisons with oral semaglutide 25 mg pointed in different directions: a peer-reviewed obesity analysis favoured semaglutide by 3.2 percentage points for weight, while the September 29 sponsor analysis in type 2 diabetes favoured Foundayo 17.2 mg by 1.5 points. Neither was a randomized head-to-head trial, and no selected comparison tested an injectable GLP-1 medicine.^{546,542,547,548}

02 How much weight loss did the main trials show?

In the 72-week FDA label trials, the 17.2 mg tablet-equivalent arm averaged 11.1% weight loss versus 2.1% with placebo in adults without diabetes. In adults with type 2 diabetes, the corresponding averages were 9.6% and 2.5%. Both trials included diet and physical-activity support.^538,545,562

03 Does food or water timing matter?

The current Foundayo label says the tablet is taken once daily with or without food and has no post-dose food or water wait. Two small crossover studies in healthy adults found lower exposure in the fed state, but the authors judged the difference unlikely to change clinical efficacy.^538,543

04 What side effects were common in the trials?

In the pooled label trials, nausea occurred in 35%, diarrhea in 25%, constipation in 24%, and vomiting in 24% at the 17.2 mg tablet-equivalent dose. The placebo rates were 10%, 11%, 9%, and 4%. These effects were most frequent while the dose was being increased and usually decreased over time.⁵³⁸

05 Why do older studies say 36 mg while the current tablet says 17.2 mg?

The pivotal studies used hard capsules. A phase 1 study in 429 adults matched six capsule strengths with lower-numbered tablet strengths; 36 mg in the capsule corresponded to 17.2 mg in the tablet. The UK product information says the two forms are not interchangeable milligram for milligram.^541,542

06 What does Foundayo cost, and where is it available?

On September 30, 2026, Lilly listed a US self-pay starting price of $149 for a 30-day supply at 0.8 mg and temporarily at 2.5 mg; the 2.5 mg discount ends December 31, 2026. Higher strengths cost more, and insurance, eligibility and refill timing can change the total. Foundayo is approved in the United States and United Kingdom, but access differs.^563,564,540

07 What is orforglipron, and is it a peptide?

Orforglipron is a small-molecule, non-peptide GLP-1 receptor agonist. Foundayo is its authorized tablet product. Oral semaglutide also targets the GLP-1 receptor, but it is a peptide with different chemistry and administration rules.^564,539,565

08 Is Foundayo approved for diabetes as well as weight loss?

In the United States, the current label is for chronic weight management in the defined adult population. The United Kingdom authorized Foundayo for both adult weight management and insufficiently controlled type 2 diabetes. Approval depends on jurisdiction and indication.^538,540,542

09 How long does it take to feel an effect?

The label does not promise a day when appetite or weight will change. It starts with a low tablet strength and increases no sooner than every 30 days, while the pivotal weight results were measured at 72 weeks.⁵³⁸

10 Does it affect birth control or other oral medicines?

The US label says the effect on oral-contraceptive absorption has not been tested in a clinical trial. Because Foundayo delays gastric emptying, the label calls for a nonoral or added barrier method for 30 days after starting and after each dose increase. It also contains specific limits for strong CYP3A4 and OATP1B inhibitors, inducers, and simvastatin.^544,538

11 Can it maintain weight after switching from an injectable GLP-1?

ATTAIN-MAINTAIN randomized 376 people after prior tirzepatide or semaglutide treatment. At week 52, selected participants who had reached a weight plateau maintained more of their earlier weight reduction with orforglipron than with placebo. The trial did not include an arm that continued the injectable medicine.⁵⁴⁹

12 Was combining it with another GLP-1 studied?

The current Foundayo label says it should not be used with another GLP-1 receptor agonist. No cited trial tested orforglipron combined with semaglutide, tirzepatide, or another GLP-1 medicine.⁵³⁸

13 What is known about long-term heart, liver, kidney, eye, and cancer risks?

The US label warns about kidney injury from dehydration, diabetic-retinopathy complications in people with type 2 diabetes, and uncertainty about thyroid C-cell tumors in people. In ACHIEVE-4, the sponsor reported cardiovascular noninferiority versus insulin glargine, with a MACE-4 hazard ratio of 0.84 (95% CI 0.59 to 1.20), but no peer-reviewed primary paper or posted registry results were identified as of September 30, 2026. The approved weight trials lasted 72 weeks, a pooled liver analysis extended to 104 weeks including follow-up, and FDA required further cardiovascular, liver, pregnancy, lactation, thyroid and pediatric studies.^{538,553,554,557,552}

14 What does the label say after a missed dose?

The label says a missed dose may be taken as soon as possible and the next dose should not be doubled. After seven or more consecutive missed doses, it calls for restarting dose escalation at a lower strength to reduce stomach and bowel reactions.⁵³⁸

15 Who should not take Foundayo?

The US label contraindicates Foundayo for people with a personal or family history of medullary thyroid carcinoma, Multiple Endocrine Neoplasia syndrome type 2, or a previous serious hypersensitivity reaction to orforglipron or its ingredients. It separately says to stop when pregnancy is recognized and does not recommend use in severe gastroparesis.⁵³⁸