When weight-loss treatment is stopped, and why it differs

Almost every page written about stopping these medicines mixes up two separate things, and the confusion matters because they point in different directions.

The first is the discontinuation criterion in the medicine's own Summary of Product Characteristics — the licensed product information a prescriber works to. It asks a clinical question: is this medicine doing enough for this person to justify continuing it? That criterion applies to you whether your treatment is NHS or private, because it belongs to the medicine rather than to the funder.

The second is a NICE technology appraisal, which decides what the NHS pays for and on what conditions. It asks a different question: given the evidence and the cost, what should be commissioned, for whom, and for how long? A NICE condition binds NHS supply. It does not describe what is clinically appropriate for a private patient, and reading it as though it does is the single most common error in this subject.

All three licensed weight-management treatments use the same threshold — a loss of at least 5% of starting body weight — and all three frame the outcome the same way. Only Saxenda's licence says treatment "should be discontinued". For Wegovy and Mounjaro the wording is that "a decision is required on whether to continue", taking the individual benefit-risk into account. That is a review, not an automatic stop.

This is the detail that changes what the dates mean for a real person, and it is almost never spelled out.

Saxenda's 12 weeks are counted from reaching the 3.0 mg daily dose, which follows about four weeks of escalation. So the review point sits around four months after the first injection, not three.

Wegovy's six months run from the start of treatment, and the escalation to 2.4 mg takes about 16 weeks of that. A substantial part of the six months is therefore spent below the maintenance dose.

Mounjaro's six months begin only once you have reached the highest dose you can tolerate. Someone who escalates slowly because of nausea, or who holds at a lower dose for a while, reaches their review point later by the calendar than someone who escalates quickly — and that is the licence working as intended rather than a delay.

The practical consequence: if you want to know when your treatment will be formally reviewed, the question is not how long you have been taking it. It is how long you have been on the dose that counts.

Five per cent of starting body weight is a clinical threshold, not a target and not a disappointment. For someone starting at 100 kg it is 5 kg; at 120 kg it is 6 kg. It is set where it is because weight loss of that order is the point at which measurable improvements in blood pressure, blood glucose and lipids begin to appear, rather than because it represents a satisfying result.

It is also used as an early signal. The evidence behind Saxenda's rule is that people who have not reached 5% by that point are unlikely to reach a substantially larger loss later: among those below 5% at 12 weeks on the treatment dose, the great majority did not go on to reach 10% at one year. The rule exists to stop people continuing an injection, and paying for it, when the early response suggests it is not the right medicine for them.

Not reaching it is not a personal failure and it is not the end of weight management. It is information about how your body responds to one molecule, and a different one may behave differently.

NICE recommends semaglutide for weight management only if it is used for a maximum of two years and within a specialist weight management service. That limit is widely quoted without its context, and the context changes what it means.

NICE's own reasoning was not that semaglutide stops being safe or effective after two years. It was that specialist weight management services — the tier 3 and tier 4 services through which the NHS supplies it — are usually accessed for up to about two years, and that the longest trial evidence available ran to two years. The committee acknowledged that limiting treatment this way was not ideal.

So it is a commissioning boundary built from service capacity and evidence duration, not a clinical ceiling. It governs NHS supply. Tirzepatide, appraised separately, carries no equivalent maximum period.

If you are treated privately, the two-year figure is not your rule. Your treatment is governed by the licence and by your prescriber's judgement, reviewed at the points described above.

A review is a conversation about whether to continue, and weight is only one of the things in it. A prescriber is also looking at how the medicine has been tolerated, whether the dose was ever actually reached, what has changed in blood pressure or blood glucose, and whether anything in your circumstances has altered since the assessment.

Several outcomes are possible other than stopping. Someone who never reached the maintenance dose because of side effects has not really had the treatment tested, and a slower titration may be the answer. Someone close to the threshold with clear metabolic improvement may reasonably continue. Someone who has not responded may be better served by a different molecule.

What should not happen is a silent continuation. If nobody has reviewed your treatment against these points, the rule is not being applied — and the rule exists for your benefit, not the prescriber's.