As far as the trials reach, yes. The longest of them follow people for two to four years, and none has found a new safety problem building up with time. In SELECT, adults without diabetes took semaglutide or placebo for up to 208 weeks, and semaglutide was associated with fewer serious adverse events [1]. That is the best available answer. Four years is also where it stops.
The rest of this page sets out what each long trial found, and what it cannot say. The short-term picture is in the side-effect guide. What happens when treatment ends is in the regain guide.
Four years of semaglutide: SELECT
SELECT enrolled 17,604 adults with established cardiovascular disease and overweight or obesity, none with diabetes. Its main result was a 20% cut in major cardiovascular events. A prespecified analysis then looked at weight and safety by starting BMI.
At 208 weeks, weight was down 10.2% on semaglutide against 1.5% on placebo. Serious adverse events ran lower on semaglutide in every BMI group. Per 100 years of observation, the rates were 43.23, 43.54, 51.07 and 47.06 on semaglutide. On placebo they were 50.48, 49.66, 52.73 and 60.85.
The same analysis records the cost. Semaglutide was associated with more discontinuation of the trial drug, and discontinuation rose as BMI class fell.
Two years: STEP 5
STEP 5 randomized 304 adults to semaglutide 2.4 mg or placebo for 104 weeks [2]. Weight fell 15.2% against 2.6%. Of the participants, 92.8% completed the trial.
Gastrointestinal adverse events were reported by 82.2% on semaglutide and 53.9% on placebo. Most were mild to moderate. That is the trade-off stated plainly: a stomach cost that most people pay, for a weight effect that held.
A meta-analysis pooled four trials of at least 68 weeks, with 3,087 participants [3]. The risk of gastrointestinal events was higher on semaglutide, a relative risk of 1.47 (95% CI 1.28 to 1.68). The authors add that most were transient, mild to moderate, and did not require stopping treatment.
Three and a half years of tirzepatide: SURMOUNT-1
SURMOUNT-1 followed 1,032 adults with obesity and prediabetes on tirzepatide 5, 10 or 15 mg or placebo for 176 weeks, then 17 weeks off [4]. Weight was down 12.3%, 18.7% and 19.7% by dose, against 1.3% on placebo.
On safety, the most common adverse events other than COVID-19 were gastrointestinal. Most were mild to moderate, and they occurred mainly during dose escalation in the first 20 weeks. The authors report no new safety signals over the three years.
The warning that no trial has settled
The Wegovy label for semaglutide carries a boxed warning on thyroid C-cell tumors [5]. In rodents, semaglutide causes them, dependent on dose and treatment duration. Whether it does so in humans is unknown, because the label states that human relevance has not been determined.
The label’s rule is a condition, not a probability. Wegovy is contraindicated with a personal or family history of medullary thyroid carcinoma, or with MEN 2. Four years of trial follow-up does not resolve a question framed in those terms.
What the trials do not answer
Nothing past four years. Nothing about people who would not have qualified for a trial. And nothing about staying on treatment in ordinary life, where about a third reach one year.
What long term costs
A benefit that depends on continued treatment is a recurring bill. Tirzepatide’s median published figure across the sellers tracked here is $249.97 a month. The range runs 8.3 times, from $83 to $687, across 365 sellers. Set that beside what the whole market charges before a first order.
Dose matters to both halves. The 10 and 15 mg doses produced more weight loss than 5 mg, and sellers often publish nothing about what a higher dose costs. Over years, the gap between an advertised price and the billed one compounds. Price figures are computed from this site’s own records at build time, most recently read September 2026, across 408 priced sellers.