Switching from 1mg Semaglutide to Tirzepatide: What Dose Comes Next?

You're at 1mg semaglutide and wondering if you've hit its ceiling

Here's a situation our prescribers see regularly: someone has been on semaglutide for several months, tolerated it well, reached the 1mg weekly dose, and now the rate of progress has slowed. The question arrives: is tirzepatide the logical next step, and if so, where does the dose begin?

The first thing to understand is that 1mg weekly is a maintenance step in the Wegovy titration schedule, not the top. The licensed maximum for Wegovy is 2.4mg weekly, and the recently approved 7.2mg pen raises that ceiling further for eligible adults. So if you haven't reached the full maintenance dose for semaglutide, the switch conversation might be premature — or it might be exactly right. That depends on side effects, tolerance, results so far, and your prescriber's assessment. Our guide on semaglutide equivalent dosing relative to tirzepatide sets out the broader clinical reasoning behind dose mapping.

Tirzepatide works through both GLP-1 and GIP receptors, while semaglutide activates only the GLP-1 pathway. That dual action produces a meaningfully different physiological response. SURMOUNT-5, published in the New England Journal of Medicine in 2025, showed greater average weight reduction with tirzepatide 15mg than with semaglutide 2.4mg over 72 weeks in adults with obesity and no diabetes. It's the most direct head-to-head evidence available, and comparing Wegovy and Mounjaro in detail shows where the trial numbers actually land.

If a switch is clinically appropriate, tirzepatide always restarts at 2.5mg regardless of the semaglutide dose you were taking. The first four weeks exist to let your system adjust to a new mechanism, not to provide therapeutic weight-loss effect. That reset can feel frustrating if you've built momentum, and it's worth being honest about that before you commit.

What a dose comparison between these two medicines actually looks like

Because the molecules are pharmacologically distinct, any dose table is a clinical approximation rather than a direct conversion. The figures below reflect the licensed UK schedules and the NICE appraisals for each medicine, not an equivalence calculation.

Sources: NICE Technology Appraisal 1026 (tirzepatide); NICE Technology Appraisal 875 (semaglutide). The table shows that the semaglutide dose you leave behind has no bearing on where tirzepatide begins. More detail on how prescribers approach this is covered in the guide to switching dosage from semaglutide to tirzepatide.

For those already on semaglutide at higher maintenance doses, the considerations shift slightly, the pages on switching from 1.7mg semaglutide and switching from 2.4mg semaglutide address those clinical pictures separately.

Side effects and practical differences worth factoring in

Both medicines share a broadly similar side-effect profile: nausea, loose stools, constipation, reflux and occasional fatigue are the most commonly reported, typically settling after a dose step rather than persisting throughout. Because tirzepatide is a new molecule to your system, some people find GI symptoms resurface even if they'd mostly resolved on semaglutide, the 2.5mg restart gives the body time to adapt.

There is one practical difference specific to tirzepatide that semaglutide users don't encounter. Women taking an oral contraceptive pill should use an additional non-oral method for the first four weeks of tirzepatide treatment and for four weeks after each dose increase, because gastric slowing can reduce pill absorption. Semaglutide doesn't carry the same MHRA guidance on this point. If you're using HRT, it's worth asking your prescriber whether transdermal preparations are more appropriate while on tirzepatide, NHS England's guidance on weight-management injections covers both points.

Storage is the same principle for both (refrigerated between uses) though the exact room-temperature window differs between products and should always be confirmed in the Patient Information Leaflet, not approximated.

How the prescribing decision is made at nume

If you're thinking about switching, the consultation is where the clinical reasoning happens. Our prescribers review your current treatment evidence, weight history and any side-effect pattern before recommending whether to continue titrating semaglutide or begin tirzepatide at 2.5mg. Neither option is better in the abstract; what suits you is a clinical decision our prescribers make with you, not a ranking we apply in advance.

For further context on how the two medicines sit relative to each other in terms of evidence and cost, the Mounjaro and Wegovy price comparison and the broader dose-conversion overview are worth reading before your consultation. You can also explore our weight-loss treatment options for a full picture of what's available through nume.

To speak to our prescribers about your specific situation, start your free consultation, it's reviewed the same day.