What Happens When You Stop a GLP-1 Medicine? What the Trials Show

If you are weighing up stopping GLP-1 medication, what happens next has been studied directly. In trials where people came off Mounjaro (tirzepatide) or Wegovy (semaglutide), much of the lost weight returned within a year on average, and improvements in measures such as blood pressure faded. In type 2 diabetes, blood sugar can rise. That does not rule out stopping; it means planning it with your prescriber.

This is information only, not medical advice. Mounjaro, Wegovy, the Wegovy pill and Foundayo are prescription-only, and a prescriber decides whether starting, continuing or stopping suits you.

Stopping GLP-1 medication: appetite and how the medicine clears

These medicines work mainly on appetite. The Mounjaro SmPC says tirzepatide cuts energy intake by increasing fullness and reducing hunger and cravings; the Wegovy SmPC describes semaglutide acting on brain areas that regulate food intake. We found no trial that measured appetite after stopping; what the withdrawal trials measured was weight. The STEP 1 extension researchers attribute the regain to physiological and behavioural factors and conclude that ongoing treatment appears necessary to keep the benefits.

The medicine clears gradually: according to the SmPCs, semaglutide has a half-life of about a week and tirzepatide about five days. That is why the product information advises stopping semaglutide at least 2 months, tirzepatide at least 1 month and orforglipron (Foundayo) at least 3 weeks before a planned pregnancy.

What the withdrawal trials found

The clearest evidence comes from three trials in adults with obesity or overweight and no diabetes. Two switched some participants, without their knowing, to a dummy injection (placebo); the third followed people after all treatment stopped.

• SURMOUNT-4 (tirzepatide). 783 adults started tirzepatide, building up to 10 or 15 mg; the 670 who reached that dose and completed 36 weeks had lost 20.9% on average. Over the next 52 weeks, weight rose by 14.0% in those switched to placebo; those who carried on lost a further 5.5%. At week 88, 89.5% of the tirzepatide group had kept at least 80% of their earlier loss, against 16.6% on placebo.
• STEP 4 (semaglutide 2.4 mg). 902 adults started semaglutide; the 803 who reached 2.4 mg during a 20-week run-in had lost 10.6% on average. Over the next 48 weeks, weight rose by 6.9% on placebo and fell by a further 7.9% in those who continued.
• STEP 1 extension (semaglutide 2.4 mg). 327 people were followed for a year after the medicine and the trial’s lifestyle programme ended at week 68. The semaglutide group had lost 17.3%; by week 120 they had regained 11.6 percentage points, about two-thirds, ending 5.6% below their starting weight (placebo group: 0.1%).

These are averages: in the STEP 1 extension, people who had lost more tended to regain more, but still kept more of it off overall. People who stopped still ended below their starting weight on average, by 9.9% in the SURMOUNT-4 placebo group. The trials tested the two weekly injections, Mounjaro and Wegovy; we have not seen comparable withdrawal results for the Wegovy pill or Foundayo.

Blood pressure, blood sugar and other health measures

In the STEP 1 extension, improvements on semaglutide in cardiometabolic measures such as blood pressure had moved back towards baseline for most measures by week 120. In STEP 4, waist size and systolic blood pressure were better in people who stayed on semaglutide than in those switched to placebo.

For people with type 2 diabetes, the Mounjaro and Foundayo leaflets warn that blood sugar can increase after stopping, and the NHS says stopping semaglutide could affect blood sugar. If you also take insulin or a sulfonylurea, those doses may have been lowered when your GLP-1 medicine started (the Mounjaro SmPC allows for this), so ask whoever manages your diabetes to review the plan first.

Why stopping should be planned with your prescriber

The UK leaflets for all four medicines say not to stop without talking to your doctor, and the NHS says not to stop suddenly, adding that your doctor may suggest reducing your dose gradually. Whether and how to taper is a prescriber decision.

A prescriber may also suggest stopping:

• Too little effect. The Mounjaro and Wegovy SmPCs and NICE require a decision on continuing if less than 5% of starting weight has gone after six months (for Mounjaro, six months after reaching the highest tolerated dose).
• NHS time limits. NICE recommends Wegovy within NHS specialist weight-management services for up to two years.
• Side effects. The MHRA says severe stomach pain spreading to the back that does not go away needs urgent help, as it can signal pancreatitis; the product information says to stop treatment if pancreatitis is suspected. Report suspected side effects through the MHRA Yellow Card scheme.

NICE’s obesity guideline says people stopping weight-management medicines should be offered support to maintain their weight loss, so ask what follow-up is available. If cost is the reason, private prices vary between regulated providers; the MHRA warns against buying from unregulated sellers such as beauty salons or social media.

Missed doses and restarting: the rules differ by medicine

A short gap is not the same as stopping. From the UK leaflets and SmPCs:

• Mounjaro: within 4 days, inject as soon as you remember; after that, skip the dose. Keep doses at least 3 days apart.
• Wegovy injection: within 5 days, inject as soon as you remember; after that, skip it and inject on your usual day.
• Wegovy pill: skip the missed tablet and take your usual dose the next day.
• Foundayo: take it as soon as you remember, never more than one tablet a day.

For restarting after a longer break, the Wegovy SmPC says a lower starting dose should be considered if more doses are missed, and the MHRA warns that switching between GLP-1 medicines without medical advice may increase side effects or reduce effectiveness. Check with your prescriber before restarting, and follow your own leaflet.

Habits that help after stopping

All four medicines are licensed alongside a reduced-calorie diet and increased physical activity, and those habits are worth keeping. The NHS recommends at least 150 minutes of moderate activity a week (or 75 vigorous) and strengthening activities on at least 2 days. Strength work matters because some lean tissue goes with the fat; see GLP-1 medications and muscle loss.

In STEP 4 and SURMOUNT-4, both groups had diet and activity advice throughout, yet weight still rose on placebo; the STEP 1 researchers said their findings confirm that obesity is a chronic condition. Agree with your prescriber in advance what to do if your weight climbs. See also our comparison and FAQ pages.

Frequently asked questions

Sources

1. SmPCs and leaflets (emc): Mounjaro KwikPen, Wegovy FlexTouch, Wegovy tablets, Foundayo.
2. NHS: Semaglutide, Tirzepatide, activity guidelines.
3. NICE: NG246, TA875 and TA1026.
4. MHRA: GLP-1 medicines: what you need to know.
5. Aronne LJ et al., SURMOUNT-4, JAMA 2024 (PubMed); Rubino D et al., STEP 4, JAMA 2021 (PubMed); Wilding JPH et al., STEP 1 extension, Diabetes Obes Metab 2022 (PubMed).

Related reading

• How do GLP-1 drugs cause weight loss?
• Managing GLP-1 side effects
• Who is eligible for GLP-1 treatment in the UK?