Is 0.5 mg Wegovy the Same as 5 mg Mounjaro?

You've switched treatments and the dose numbers don't line up, here's why

Imagine you've been on Wegovy for a few months, currently taking 0.5 mg weekly, and your pharmacist or a friend suggests trying Mounjaro instead. You look at the dose numbers and wonder whether 5 mg Mounjaro is the equivalent step. It isn't, and not because one is stronger per milligram, but because the two medicines measure different molecules acting through different biological mechanisms.

Semaglutide (Wegovy) and tirzepatide (Mounjaro) cannot be compared by milligram count alone. The 0.5 mg figure in Wegovy refers to the mass of semaglutide delivered per weekly injection. The 5 mg figure in Mounjaro refers to the mass of tirzepatide. These molecules have different molecular structures, different receptor targets, and different clinical dose ranges entirely. Wegovy's maintenance doses run from 0.25 mg up to 2.4 mg (or the newer 7.2 mg pen). Mounjaro's titration runs from 2.5 mg up to 15 mg. The sheer difference in numerical scale reflects the different potency and pharmacology of each molecule, not a meaningful strength ranking between the two.

If you are thinking about switching between these medicines, the question of dose conversion is one only a prescriber can properly answer. There is no published one-to-one equivalence table for clinical use.

Where 0.5 mg Wegovy and 5 mg Mounjaro actually sit in their respective titration schedules

Context matters here. Wegovy's licensed titration starts at 0.25 mg for the first four weeks (a period designed to let your body settle) then moves to 0.5 mg for the next four weeks. So 0.5 mg is the second rung, still in the early adjustment phase, well below the standard 2.4 mg maintenance dose. Mounjaro begins at 2.5 mg (again, a tolerability step rather than a full therapeutic dose), moving to 5 mg at around week five. Both 0.5 mg Wegovy and 5 mg Mounjaro are therefore mid-early-titration doses in their own ladders, but that positional similarity doesn't make them equivalent in effect.

The table below summarises where each sits, factually, without implying equivalence.

Those trial figures are maintenance-dose results, neither 0.5 mg Wegovy nor 5 mg Mounjaro was tested as a standalone long-term dose in these trials. They are milestones on the way to maintenance, not endpoints. For a fuller picture of how these two treatments compare at their respective maintenance doses, the Wegovy vs Mounjaro comparison covers the evidence in detail, including the SURMOUNT-5 head-to-head trial published in 2025.

What this means if you are trying to compare costs at these dose levels

A practical check you can do in under a minute: look at the box or pen you're holding and confirm both the medicine name (semaglutide or tirzepatide) and the dose printed on the label, since the pen colour alone can mislead. This matters especially for cost comparisons, because Wegovy and Mounjaro pens are priced per pen at different dose steps, and a 0.5 mg Wegovy pen and a 5 mg Mounjaro pen sit at different positions in their dose ladders, dispensed for different durations, so the monthly cost arithmetic is not straightforward.

Eli Lilly raised Mounjaro's UK list price from 1 September 2025, with private prices reported to range roughly £149–£375 per month depending on dose and provider. Wegovy prices vary similarly. What that means at the 0.5 mg or 5 mg level specifically depends on how your provider prices each tier. The price difference between Mounjaro and Wegovy covers the broader cost picture. At nume, one transparent price covers consultation, prescription, the treatment and aftercare, current treatment pricing is on the treatment page rather than buried in body copy, because it can change. We are not the cheapest option (that's a choice, not an oversight) and for a prescription medicine, price is the wrong measure to lead with anyway. The right measure is whether the medicine is genuine, clinically appropriate and properly supervised.

You can verify any online pharmacy on the GPhC pharmacy register, our registration number is 9012878. It takes seconds. The MHRA has warned repeatedly about counterfeit weight-loss pens sold online, including fake tirzepatide pens seized in the UK in 2025, so that check is genuinely worth doing before you order from any provider.

Which medicine and dose is actually right for you

The titration schedule each person follows is set by their prescriber based on their clinical picture, tolerance, any side effects, other medicines, and how their weight is responding. Swapping from 0.5 mg Wegovy to 5 mg Mounjaro, or the other way around, is not a like-for-like substitution. The prescriber would need to assess your history and restart titration appropriately.

Both medicines share a broadly similar side-effect profile in practice, nausea, digestive discomfort and fatigue are most commonly reported at the start of treatment or after each dose increase, and generally settle. The NHS tirzepatide guidance and the NHS semaglutide page both describe what to watch for. On the contraception front, tirzepatide specifically can reduce the absorption of oral contraceptive pills during the first four weeks of treatment and for four weeks after each dose increase, so additional contraception (such as condoms) is advised during those windows, worth discussing with your prescriber if you are considering switching to Mounjaro.

For related dose-level comparisons, you may also find it useful to read about whether 0.25 mg Wegovy equates to 2.5 mg Mounjaro, or whether 1 mg Wegovy lines up with 7.5 mg Mounjaro, neither comparison is a simple yes. More detail on the broader question of whether Wegovy 2.4 mg and Mounjaro 2.5 mg are equivalent is also available. Which medicine and which dose suits you is a clinical decision, one our prescribers make with you, based on your individual circumstances.