- In OASIS 1, adults without diabetes who took a daily 50 mg semaglutide pill lost 15.1% of their body weight on average over 68 weeks, vs 2.4% on placebo.1
- In OASIS 4, a lower daily dose of 25 mg led to an average loss of 13.6% at week 64, vs 2.2% on placebo.2
- Stomach and gut side effects were common with the pill, as they are with the weekly shot. Most were mild to moderate.1,2
Why a pill matters
Semaglutide is best known as a weekly injection. Some people would rather not inject, and some find a daily routine easier to keep than a weekly one. The OASIS trials asked whether the same medicine, taken by mouth once a day, could lead to similar weight loss.
Both trials described here were funded by the maker, Novo Nordisk, and both compared the pill with a look-alike placebo. Everyone in both groups also got lifestyle support, so the placebo group shows what that support achieved on its own.
OASIS 1: a 50 mg daily pill for 68 weeks
OASIS 1 enrolled 667 adults at 50 clinics in nine countries across Asia, Europe and North America. To join, people needed a BMI of at least 30, or at least 27 with a weight-related health problem. People with type 2 diabetes were not included. Half were assigned to oral semaglutide, raised step by step to 50 mg a day, and half to placebo.1
These averages count everyone who was assigned a group, including people who stopped the pill along the way. That makes them a fair picture of what happened in the trial as a whole, not just among people who took every dose.
How many people reached each milestone
| Weight lost at week 68 | Oral semaglutide 50 mg | Placebo |
|---|---|---|
| 5% or more | 85% | 26% |
| 10% or more | 69% | 12% |
| 15% or more | 54% | 6% |
| 20% or more | 34% | 3% |
About half of the people on the pill lost 15% or more, and about a third lost 20% or more. On placebo, very few reached those levels.
OASIS 4: a 25 mg daily pill
OASIS 4 tested half the OASIS 1 dose. It enrolled 307 adults without diabetes at 22 sites in four countries, with the same BMI rules. Two in three were assigned to oral semaglutide 25 mg a day and one in three to placebo. The main results were measured at week 64 of a 71-week trial.2
The gap between the groups was 11.4 percentage points. People on the pill were also more likely than those on placebo to lose at least 5%, 10%, 15% and 20% of their weight, and they reported better scores on a questionnaire about physical function.2
How the pill compares with the weekly shot
The best-known trial of the weekly semaglutide 2.4 mg injection is STEP 1. In a similar population of adults without diabetes, people on the injection lost 14.9% on average over 68 weeks, vs 2.4% on placebo.3 You can read more in our guide to STEP 1 and SURMOUNT-1.
| Trial | Form | Length | Medicine | Placebo |
|---|---|---|---|---|
| STEP 1 | Weekly injection, 2.4 mg | 68 weeks | −14.9% | −2.4% |
| OASIS 1 | Daily pill, 50 mg | 68 weeks | −15.1% | −2.4% |
| OASIS 4 | Daily pill, 25 mg | 64 weeks | −13.6% | −2.2% |
Side effects
As with other GLP-1 medicines, the most common side effects were in the stomach and gut, such as nausea.
| Oral semaglutide | Placebo | |
|---|---|---|
| OASIS 1 (50 mg): any gastrointestinal side effect | 80% | 46% |
| OASIS 1 (50 mg): any side effect | 92% | 86% |
| OASIS 4 (25 mg): any gastrointestinal side effect | 74.0% | 42.2% |
In OASIS 1, the gastrointestinal events were mostly mild to moderate.1 Notice that many people on placebo also reported stomach symptoms. In trials, some of what people feel is everyday background, not the medicine. For more on timing and what helps, see our article on GLP-1 nausea and stomach side effects.
Reading these results
- Who was studied. Both trials enrolled adults with obesity, or overweight plus a weight-related health problem, and without type 2 diabetes. Results may differ for people with diabetes, for teenagers, or for people with other conditions.
- Doses are not interchangeable. The pill doses tested here (25 mg and 50 mg a day) are set separately from injection doses. The milligrams cannot be compared across forms.
- Averages hide a wide range. In OASIS 1, about a third of people on the pill lost 20% or more, while about 15% lost less than 5%.
- Weight tends to return after stopping. These trials did not follow people after the pill was stopped, but trials of the injection did. See what happens when you stop a GLP-1.
Whether a pill, a shot or neither suits you depends on your health, other medicines, cost and access. That is a conversation for your prescriber.
Sources
- Knop FK, Aroda VR, do Vale RD, et al. Oral semaglutide 50 mg taken once per day in adults with overweight or obesity (OASIS 1): a randomised, double-blind, placebo-controlled, phase 3 trial. Lancet. 2023;402:705-719. PubMed · doi:10.1016/S0140-6736(23)01185-6
- Wharton S, Lingvay I, Bogdanski P, et al. Oral Semaglutide at a Dose of 25 mg in Adults with Overweight or Obesity. N Engl J Med. 2025;393:1077-1087. PubMed · doi:10.1056/NEJMoa2500969
- Wilding JPH, et al. Once-Weekly Semaglutide in Adults with Overweight or Obesity (STEP 1). N Engl J Med. 2021;384:989-1002. PubMed
