Head to head
Mounjaro vs Saxenda
A weekly pen against a daily one, and the widest gap in average weight loss of any pairing on this site. It is also the comparison where the cheaper headline price is easiest to misread — so that is worth getting straight before anything else.
Tirzepatide
Mounjaro
1 a week
Around 52 injections a year
- Acts on two receptors, GLP-1 and GIP
- Six strengths, 2.5mg to 15mg
- Four to five months to the top strength
- Licensed for weight management in 2023
- Needles usually supplied separately
Liraglutide
Saxenda
1 a day
Around 365 injections a year
- Acts on one receptor, GLP-1
- Five strengths, 0.6mg to 3mg
- About five weeks to the maintenance dose
- The longest track record of the three
- Needle built into the pen
The price per pen is the wrong number
Saxenda is often quoted per pen and Mounjaro per month, and the two get compared as though they were the same unit. They are not. A daily pen empties far faster than a weekly one, so a low price per pen can mean more pens — and the only figure that settles it is what a month of treatment costs at the strength you would actually be on.
There is a second trap underneath it. Saxenda reaches its maintenance dose in about five weeks, so you are paying the full-strength price almost immediately. Mounjaro takes four to five months to climb, and the low starting strengths cover much of that. Comparing a Saxenda maintenance price against a Mounjaro starting price is not a comparison at all.
Where the difference is real
Daily against weekly
The clearest difference, and the one a price table cannot show. 365 injections in a year against 52 asks something different of the person taking it — and neither pattern is the wrong answer.
The evidence gap
This is the widest gap of any pairing here. On the trial evidence, tirzepatide produces substantially greater average weight loss than liraglutide. Saying otherwise would not be fair to a reader.
Why Saxenda is still prescribed
A longer track record, and a shorter-acting medicine that clears faster if it does not suit you. Supply has also decided this more often than preference has.
Which should you choose?
On average weight loss the evidence favours tirzepatide, and we are not going to soften that. But average weight loss is one input among several, and it is not the one that decides most prescriptions.
A medicine you can keep taking beats one you stop after a month, and a daily injection is a daily commitment that suits some people and defeats others. Your history, what else you take, and what is actually in stock all narrow the choice before preference gets a say. That makes it a prescriber’s decision — but you can make the conversation a better one.
Take these to your consultation
- Realistically, could I keep to a daily injection?
- Given my history, is one of these more suitable than the other?
- Does anything else I take interact with either?
- What would a month of treatment cost me at my maintenance dose?
- If side effects are difficult, what would you try before stopping?
Compare a month, not a pen
We have deliberately not printed prices on this page. UK providers price each strength separately and change what they charge, so a figure typed into an article is out of date shortly after it is written. Each listing below shows the complete cost at that strength, including consultation and delivery fees, alongside the date it was last checked — which is the only way to compare these two honestly.
Sources
- Summaries of product characteristics for both products, electronic medicines compendium
- Jastreboff AM and others, SURMOUNT-1, New England Journal of Medicine, 2022
- Pi-Sunyer X and others, SCALE, New England Journal of Medicine, 2015
PenCompare is an independent comparison platform, not a pharmacy or a prescriber. This page is information, not medical advice, and not a recommendation to take any medicine. Both products are prescription-only.