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What is the NICE 5% rule, and when does the NHS stop a weight-loss jab?

The 6-month review for Wegovy and Mounjaro, and Saxenda’s stricter 12-week rule. Plus the 2-year limit, and what tends to happen after stopping.

GLP Guidebook teamPublished 12 Oct 20264 min read13 sourcesWritten from published sources

Written for the UK. Reading from India? India version

The short answer

NICE asks for a review if you have lost less than 5% of your starting weight after 6 months. For Wegovy, NICE says to consider stopping; for Mounjaro, to decide whether to continue, counting from the highest dose you tolerate. For a 100 kg person, 5% is 5 kg. NHS Wegovy for weight also ends after 2 years.

Key takeaways

  • For Wegovy, NICE says to consider stopping if less than 5% of starting weight is lost after 6 months of treatment.1
  • For Mounjaro, NICE’s wording is softer: if under 5% is lost after 6 months on the highest tolerated dose, decide whether to continue.2
  • In STEP 1, about 90 in 100 people on Wegovy 2.4 mg had lost at least 5% by about 28 weeks; about 4 in 10 of the rest got there by week 68.3
  • Saxenda has a stricter rule in its UK licence: stop after 12 weeks on the 3 mg dose if at least 5% hasn’t been lost.4,5
  • NHS Wegovy for weight has a 2-year maximum in specialist services, while NHS Mounjaro currently has no specified time limit.1,6
Before you go further
  • GLP‑1 medicines are prescription-only medicines in the UK, never sold over the counter.7
  • Ozempic and Rybelsus are licensed for type 2 diabetes only, not for weight loss.8
  • A prescriber decides whether a medicine fits, which one and at what dose. Nothing here is a recommendation.
  • The risks are the same however you get it: see our side effects guide.
On this page
  1. What exactly does the 5% rule say?
  2. What does 5% mean in kilograms?
  3. Why does the review come at 6 months?
  4. What happens if the NHS stops the medicine?
  5. Is there a time limit as well?
  6. Questions people ask
  7. How we researched this
  8. Sources

What exactly does the 5% rule say?

NICE asks for a review when weight loss is under 5% of starting weight at a set point; the wording differs by medicine.5

MedicineReview pointNICE wording
Wegovy Semaglutide6 months of treatmentConsider stopping
Mounjaro Tirzepatide6 months on the highest tolerated doseDecide whether to continue, weighing benefits and risks
Saxenda Liraglutide12 weeks on the 3 mg daily doseStop
Orlistat Not a GLP‑112 weeksStop

Each row applies when less than 5% of starting weight has been lost. Source: NICE NG246, Table 1; TA875; TA1026.5,1,2

The UK labels carry the same idea. For Wegovy and Mounjaro, they say “a decision is required on whether to continue treatment”.3,9 Saxenda’s label says treatment “should be discontinued”.4

What does 5% mean in kilograms?

Your starting weight divided by 20: for someone who began at 100 kg (15 st 10 lb), 5% is 5 kg (11 lb).

4 kgStarting at 80 kg (12 st 8 lb): 9 lb
5 kgStarting at 100 kg (15 st 10 lb): 11 lb
6 kgStarting at 120 kg (18 st 13 lb): 13 lb
7 kgStarting at 140 kg (22 st 1 lb): 1 st 1 lb

Our arithmetic: 5% of starting weight, rounded.

NICE measures it against your “initial weight”, meaning your weight when treatment began.1 Our guide to weight and health explains BMI and waist measures.

Why does the review come at 6 months?

Because most people have shown a response by then: in STEP 1, about 90 in 100 people on Wegovy 2.4 mg had lost at least 5% by about 28 weeks.3

That leaves about 10 in 100 who hadn’t. Of those, about 4 in 10 (40.5%) still reached 5% by week 68.3 So roughly 4 in 100 people were slow responders, and about 6 in 100 never reached 5%.

For Mounjaro, the clock runs from the highest dose you tolerate.2 Doses rise in steps of at least 4 weeks.10 Say the dose rose every 4 weeks to 15 mg. The review would then fall about 46 weeks after the first injection.

In SURMOUNT-1, about 89 to 96 in 100 people on Mounjaro lost at least 5% over 72 weeks, depending on dose, against about 28 in 100 on a dummy injection.10 These are trial averages; your own response may differ.

RisksThe risks, in brief
  • Stomach effects. In the main trials, about 44 in 100 people on Wegovy 2.4 mg felt sick (nausea), against about 16 in 100 on a dummy injection. On Mounjaro it was about 25 to 29 in 100, against about 9 in 100 on a dummy injection. It mostly comes while the dose goes up.3,9
  • Gallbladder problems. Gallstones were reported in about 16 in 1,000 people on Wegovy 2.4 mg. Acute gallbladder disease affected about 20 in 1,000 on Mounjaro, against about 16 in 1,000 on a dummy injection.3,9
  • Pancreatitis (an inflamed pancreas): severe stomach pain that won’t go away and may spread to the back. The MHRA updated its guidance on it in January 2026.11
  • Dehydration from vomiting or diarrhoea can harm the kidneys.9,3
  • Surgery and pregnancy. Tell the team before any anaesthetic. The MHRA advises stopping semaglutide at least 2 months before a planned pregnancy, tirzepatide 1 month.8
Full detail in our side effects guide →
Get help now: call 999 or go to A&E for severe stomach pain that won’t go away, with or without vomiting. It can be pancreatitis. Not sure? Use NHS 111 (in Northern Ireland, your GP’s out-of-hours service).11,12
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What happens if the NHS stops the medicine?

NICE says to offer support to keep weight off, but trials show much of the lost weight tends to come back.5,13

The STEP 1 extension followed 327 people from both trial groups after all treatment stopped at week 68. Those on Wegovy had lost an average of 17.3% of their body weight. A year later they had regained 11.6 percentage points, a net loss of 5.6%, against 0.1% for the dummy-injection group.13 The authors called it two-thirds of the weight lost.13

NICE says people stopping weight medicines should be offered support to keep weight off.5 Our stopping post and stopping guide cover what helps.

Is there a time limit as well?

For NHS Wegovy, yes: a maximum of 2 years in a specialist service; NHS Mounjaro currently has no specified time limit.1,6

NICE says specialist weight services, where Wegovy and Saxenda are used, “are usually accessed for up to 2 years”.5 Mounjaro can be prescribed in primary care, and one ICB says there is currently no specified time limit.2,6

The 5% rules for Wegovy and Mounjaro appear in NICE guidance and in the UK labels. So private prescribers see them too.3,9 Our Wegovy on the NHS post explains the 2-year limit.

Questions people ask

Will the NHS stop my Mounjaro if I lose less than 5%?

Not automatically. NICE says to decide whether to continue, weighing benefits and risks, after 6 months on the highest tolerated dose.2

Does the 5% rule apply to private prescriptions?

The UK labels for Wegovy and Mounjaro call for a decision on continuing if 5% isn’t lost by 6 months. The prescriber makes it.3,9

When does the 6-month clock begin for Mounjaro?

From when you reach the highest dose you can tolerate, not from the first injection.2

What is the rule for Saxenda?

Its UK label says to stop after 12 weeks on the 3 mg daily dose if under 5% of weight is lost.4

How long can I stay on Wegovy on the NHS?

For weight, NICE recommends it for a maximum of 2 years in a specialist service.1

How we researched this

On 12 October 2026 we read NICE NG246 (Table 1), TA875 and TA1026. We also read the UK labels for Wegovy, Mounjaro and Saxenda. Trial figures come from the labels and the STEP 1 extension paper.

The kilogram and timing examples are our arithmetic.

Before you move on

  • Write down your starting weight and the date.
  • Know your 5% figure: starting weight divided by 20.
  • For Mounjaro, note when you reached your highest tolerated dose.
  • Ask what support is offered if the medicine stops.
  • For NHS Wegovy, plan for the 2-year end point.
Doctor questionsAlready on a GLP‑1Weight and health

More from the UK blog

UKUnited KingdomCan you get Wegovy on the NHS? Specialist services, the 2-year limit and the heart routeUKUnited KingdomStopping Mounjaro or Wegovy: weight regain, tapering and breaksUKUnited KingdomCan I get Mounjaro on the NHS in 2026? Who qualifies in England, Scotland, Wales and Northern Ireland
About GLP Guidebook

The monthly UK update

An independent guide to GLP‑1 medicines. We don’t sell medicines, take drug-company money, earn commissions or link to any provider. Once a month: NHS changes, approvals, list prices and safety alerts. How we write

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Sources

  1. NICE. Semaglutide for managing overweight and obesity, technology appraisal TA875, section 1. Published 8 March 2023, last updated 4 September 2023. Link
  2. NICE. Tirzepatide for managing overweight and obesity, technology appraisal TA1026, section 1 (recommendations and “What this means in practice”). Published 23 December 2024, last updated 1 September 2025. Link
  3. Novo Nordisk. Wegovy FlexTouch: UK summary of product characteristics (SmPC), electronic Medicines Compendium. Date of revision 09/2026. Link
  4. Novo Nordisk. Saxenda 6 mg/ml pre-filled pen: UK summary of product characteristics (SmPC), electronic Medicines Compendium. Date of revision 11/2025. Link
  5. NICE. NG246, section on medicines and surgery (Table 1: when to stop treatment). Link
  6. NHS Cheshire and Merseyside (integrated care board). Tirzepatide (Mounjaro) for obesity: information for patients from 1 April 2026. Link
  7. MHRA. UK first in Europe to authorise orforglipron for weight management and type 2 diabetes. Press release, 10 August 2026. Link
  8. MHRA. GLP-1 medicines for weight loss and diabetes: what you need to know. Guidance, published 5 June 2025, updated 5 February 2026. Link
  9. Eli Lilly. Mounjaro KwikPen: UK summary of product characteristics (SmPC), electronic Medicines Compendium. Date of revision 29 August 2026. Link
  10. MHRA. MHRA authorises diabetes drug Mounjaro (tirzepatide) for weight management and weight loss. Press release, 8 November 2023. Link
  11. MHRA. MHRA updates guidance for GLP-1 prescribers and patients. Press release, 29 January 2026. Link
  12. NHS. When to call 999. Link
  13. Wilding JPH et al. Weight regain and cardiometabolic effects after withdrawal of semaglutide: the STEP 1 trial extension. Diabetes Obes Metab 2022;24:1553–64. PMID 35441470. Link

Last checked 12 Oct 2026 · Next review due 12 Apr 2027 · Report an error

How this post was made. Written by the GLP Guidebook team from the sources above. It’s general information, not medical advice. Talk to your GP, pharmacist or prescriber before starting, stopping or changing any medicine. We don’t sell, prescribe or recommend any brand or provider. How we write