The semaglutide injection is a once-weekly prescription medication that is FDA-approved for chronic weight management, used alongside a reduced-calorie diet and more physical activity. It is started at a low dose and built up gradually over about four months to a maintenance dose of 2.4 mg, and in pooled clinical trials it produced average weight loss of roughly 11 percentage points more than placebo. What follows is the dosing schedule, the results from the major trials, and the full safety profile.
Semaglutide is prescription-only and is not right for everyone. Individual results vary, and the information here is educational, not a substitute for evaluation by a licensed healthcare provider.
Semaglutide is a GLP-1 receptor agonist, a medication that mimics a natural gut hormone to reduce appetite and slow stomach emptying, so you feel full sooner and eat less. The injectable version for weight management is sold under the brand Wegovy. The FDA has approved the semaglutide injection, as an addition to diet and physical activity, for chronic weight management in adults and in children aged 12 and older with obesity, and in adults with overweight who have at least one weight-related condition.
It also carries two further approvals: reducing the risk of major adverse cardiovascular events in adults with established cardiovascular disease who have obesity or overweight, and treating a form of fatty liver disease (noncirrhotic MASH with moderate to advanced fibrosis) under accelerated approval. As of December 2025, a once-daily oral 25 mg tablet of semaglutide was also approved for chronic weight management in adults, though the once-weekly injection remains the most established form. Whether any of these applies to you is a decision for a provider.
The semaglutide injection is deliberately started low and increased every four weeks. This slow titration is the main strategy for limiting the gastrointestinal side effects that are common early on. The standard schedule is:
| Phase | Dose (once weekly) | Purpose |
| Weeks 1 to 4 | 0.25 mg | Starting dose to let the body adjust; not a weight loss dose |
| Weeks 5 to 8 | 0.5 mg | First increase |
| Weeks 9 to 12 | 1.0 mg | Second increase |
| Weeks 13 to 16 | 1.7 mg | Third increase |
| Week 17 onward | 2.4 mg | Recommended maintenance dose |
If a dose is not well tolerated during the build-up, the provider may delay the next increase by four weeks rather than push ahead. If the full 2.4 mg maintenance dose is not tolerated, it can be reduced to 1.7 mg. The injection can be given in the abdomen, thigh, or upper arm on the same day each week, at any time of day, with or without food. If you miss a dose and your next one is more than 48 hours away, take it as soon as you remember; if it is less than 48 hours away, skip it. After missing more than two doses in a row, providers often restart with the escalation schedule rather than jumping back to the full dose.
The low starting dose matters: at 0.25 mg, semaglutide is not yet at a weight loss dose. That first month is about helping your stomach and gut adjust so that the higher, effective doses are easier to tolerate later. Trying to rush the schedule usually backfires, because it makes nausea and other gut symptoms worse without speeding up results. Patience through the titration phase is one of the better predictors of staying on treatment long enough to see the benefit.
Semaglutide has high-certainty evidence behind it. The American Gastroenterological Association recommends it for treating obesity, citing a pooled analysis of eight randomized trials in which semaglutide produced an average of 10.76 percent more total body weight loss than placebo, an absolute difference of about 10.8 kg. In that analysis, 82 percent of semaglutide-treated patients lost at least 5 percent of body weight, 65 percent lost at least 10 percent, and 46 percent lost at least 15 percent, all far above placebo.
The STEP trial program provides the core efficacy data:
A 2025 Cochrane systematic review of 15 studies and 8,651 participants confirmed the high-certainty finding, with semaglutide reducing body weight by about 10.7 percentage points more than placebo and making people more than five times as likely to lose at least 10 percent of their weight. These are trial averages, and your own results may be higher or lower.
Gastrointestinal side effects are the most common, affecting roughly 74 percent of semaglutide-treated patients versus about 48 percent on placebo in STEP 1. They are usually mild to moderate, tend to appear during dose increases, and most resolve without stopping treatment.
Stopping treatment because of side effects happened in about 7 percent of semaglutide patients versus 3 percent on placebo, mostly due to gastrointestinal symptoms. Other safety considerations include a modest rise in heart rate (about 10 to 19 beats per minute in 41 percent of patients), a higher rate of gallbladder problems such as gallstones, and rare cases of acute pancreatitis, for which the medication should be stopped if suspected and not restarted after a confirmed episode. Dehydration from significant vomiting or diarrhea can occasionally lead to acute kidney injury, so kidney function is monitored in anyone with persistent gastrointestinal symptoms. Side effects can often be eased with gradual titration, smaller low-fat meals, good hydration, and supportive medications when needed. Talk to a healthcare provider about managing any side effects you experience.
Semaglutide is not appropriate for everyone. It is contraindicated in people with a personal or family history of medullary thyroid carcinoma or the genetic condition multiple endocrine neoplasia type 2, based on thyroid C-cell tumor findings in rodent studies. It should be stopped at least two months before a planned pregnancy because of potential harm to a developing fetus. And in people who also take insulin or insulin-stimulating diabetes medications, semaglutide can increase the risk of low blood sugar, so those medications may need to be reduced.
This is why a full medical history and medication review are part of starting treatment, and why the injection is prescription-only. A provider will weigh your conditions, other medications, and goals before recommending it.
It also helps to know what semaglutide is not for. It is not approved for cosmetic or short-term weight loss in people without obesity or a qualifying weight-related condition, and using it that way falls outside the evidence and the label. It is also meant to work with changes to diet and activity, not in place of them. The trial results that make semaglutide so effective were all achieved with lifestyle support built in, which is part of why a structured, medically supervised program tends to produce better and longer-lasting results than a prescription on its own.
The evidence indicates that long-term use is generally necessary to keep the weight off. In a follow-up of people who completed 68 weeks of semaglutide and then stopped, participants regained an average of about 11.6 percent of body weight over the next 52 weeks. In the STEP 4 trial, people who switched from semaglutide to placebo after 20 weeks regained about 6.9 percent of lost weight over the following 48 weeks, while those who stayed on it kept losing.
In short, semaglutide manages obesity as a chronic condition rather than curing it, so the benefits depend on staying on treatment. Any decision to stop should be made with your provider, who can help plan a maintenance approach.
How often is the semaglutide injection given?
Once a week, on the same day each week, under the skin of the abdomen, thigh, or upper arm. The dose is increased every four weeks during the first months to a maintenance dose of 2.4 mg.
How much weight will I lose on semaglutide?
In trials, adults without diabetes lost an average of about 15 percent of body weight over 68 weeks, and pooled analyses show roughly 11 percentage points more loss than placebo. These are averages, and individual results vary.
What are the most common side effects?
Gastrointestinal symptoms, mainly nausea, diarrhea, vomiting, and constipation, are most common and usually mild to moderate. They tend to occur during dose increases and ease over time.
Who should not use semaglutide?
People with a personal or family history of medullary thyroid carcinoma or MEN2 should not use it. It should also be stopped before a planned pregnancy, and care is needed when combined with insulin. A provider will review your history.
Do you regain weight after stopping?
Yes, weight regain is common after stopping, which is why semaglutide is generally considered a long-term treatment. Your provider can help you plan for maintenance.
Learn more: FDD Weight Loss Program | Eligibility quiz
