Wegovy tablets vs Mounjaro: pill or weekly injection?

Most comparisons declare a winner in the first paragraph. Here is what they tend to leave out: Wegovy tablets and Mounjaro have never been tested against each other in a clinical trial. What we have instead are separate trials, run in different groups of people over different lengths of time. They tell you a lot, but they do not tell you which medicine is better for you.

What are Wegovy tablets and Mounjaro?

Wegovy tablets contain semaglutide, a GLP-1 receptor agonist. It is the same active ingredient as the Wegovy injection, in a once-daily tablet. It is a different product from Rybelsus, the semaglutide tablet licensed for type 2 diabetes, and the two are not interchangeable. The MHRA licensed the tablet on 11 June 2026 and it became available on private prescription in the UK from July.

Mounjaro contains tirzepatide, given as a once-weekly injection from a pre-filled pen. Both medicines are licensed for weight management alongside a reduced-calorie diet and increased physical activity, for adults with a BMI of 30 or more, or 27 or more with a weight-related health condition. Both are prescription-only, and neither is intended as a short course.

How do they work?

Semaglutide copies a gut hormone called GLP-1. It tells your brain you are full, slows how quickly your stomach empties and helps you feel satisfied on smaller meals. Tirzepatide acts on two receptors rather than one, GLP-1 and GIP, which may explain the larger average loss seen in its trials.

Day to day the effect feels similar: less hunger, less food noise, fuller sooner. The differences you will actually notice are in the routine.

Daily tablet or weekly injection?

The tablet is swallowed whole with up to 120ml of water, about half a glass, after at least eight hours without food. Nothing else to eat or drink, and no other medicines, for at least 30 minutes afterwards. That means no coffee first thing and no just a biscuit, every day.

The routine matters because semaglutide is a peptide your stomach would normally digest. The tablet uses an absorption enhancer to get a small amount through, and anything else in your stomach gets in the way. Mounjaro asks for less discipline and a little more courage: one injection a week into the abdomen, thigh or upper arm, rotating the site each time.

What the trials found

Three things stand out. The tablet's result sits close to the injection form of the same medicine, which is what you would expect. Mounjaro's advantage has been shown directly, but only against the Wegovy injection. And the averages hide a wide range: in OASIS 4 around 30% of people on the tablet lost 20% or more of their body weight, while others lost considerably less.

Side effects

Both medicines slow digestion and reduce appetite, so the common side effects are the same: nausea, vomiting, diarrhoea, constipation and stomach discomfort. They are usually mild to moderate, tend to appear around dose increases and generally settle as the body adjusts.

In OASIS 4, gut-related side effects affected 74% of people on the tablet against 42% on placebo, but only around 7% stopped treatment because of them — similar to the placebo group.

For Mounjaro, nausea, diarrhoea, vomiting, constipation and abdominal pain are all listed as very common, with tiredness, dizziness, hair loss, injection-site reactions and gallstones listed as common. In SURMOUNT-1 roughly 4% to 7% of people stopped because of side effects, against about 3% on placebo. In the head-to-head against the Wegovy injection, slightly fewer people on Mounjaro stopped because of gut problems: 2.7% against 5.6%.

Storage and travel

The tablet needs no refrigeration. Keep it in its original packaging away from light and moisture and it will travel anywhere. Mounjaro pens are kept in the fridge between 2°C and 8°C until first use; once in use a pen can stay below 30°C for up to 30 days and is then discarded. Fine for most holidays, less convenient somewhere hot without reliable cooling.

Other medicines, contraception and pregnancy

• The contraceptive pill: Mounjaro can reduce how well it is absorbed. The leaflet advises a barrier method or non-oral contraception for four weeks after starting and four weeks after each dose increase.
• Other tablets: with Wegovy tablets, anything else oral waits at least 30 minutes. Levothyroxine exposure rose by about a third in studies, so thyroid levels may need monitoring, and warfarin means extra INR checks.
• Pregnancy: neither medicine should be used. Semaglutide is stopped at least two months before trying to conceive, tirzepatide at least one month.
• Breastfeeding: the tablet's licence says semaglutide should not be used; tirzepatide's says it could be considered.

Missed doses and switching

Miss a tablet and you skip it, then take your usual dose the next day. Never two. Miss a Mounjaro injection and you take it as soon as you remember if you are within four days, then carry on as normal; beyond four days you skip it and inject on your usual day, keeping at least three days between injections.

Switching between them is possible under medical supervision, never by taking both at once. There is no dose of one that equals a dose of the other, so you restart the new medicine at its lowest strength. The one exception sits within the same medicine: people established on the 2.4mg Wegovy injection can move straight to the 25mg tablet, seven days after their last injection.

NHS availability and private prescriptions

Mounjaro is available on the NHS, but in stages. NICE recommends tirzepatide for adults with a BMI of 35 or more and at least one weight-related condition, with lower thresholds for people from some ethnic backgrounds. NHS England began a phased rollout in June 2025, starting with a BMI of 40 or more and at least four qualifying conditions, and full coverage is expected to take years.

Wegovy tablets are private-only for now and will stay that way unless NICE assesses them. Privately, the licence criteria decide eligibility: a BMI of 30 or more, or 27 or more with a weight-related condition. Because both are prescription-only medicines, we do not publish prices in our guides.

Choosing between them

Rather than asking which is best, ask which one you will manage well month after month. Five questions usually get to the answer.

1. 1Can I realistically fast for eight hours and wait 30 minutes every morning? If not, the tablet will be a daily battle.
2. 2Do I take other morning medicines that cannot be moved? Thyroid tablets, for example, complicate the tablet routine.
3. 3Do I have a reliable fridge at home and when I travel? If not, the pen becomes awkward.
4. 4Am I on the contraceptive pill, and happy to add a barrier method during dose increases?
5. 5Have I already tried semaglutide? If it did not do enough, that is a genuine reason to discuss tirzepatide.

Take your answers to a consultation. Your prescriber will weigh them alongside your BMI, your medical history and your blood tests, and explain which options are actually suitable for you.

When to speak to a clinician

Contact your prescriber promptly if vomiting or diarrhoea stops you keeping fluids down for more than a day, if you feel faint when you stand, or if a side effect has you thinking about stopping. Call 111, or 999 in an emergency, for severe and persistent stomach pain, signs of an allergic reaction such as facial swelling or difficulty breathing, or symptoms of low blood sugar if you also use insulin. Do not start, stop or change the dose of either medicine without speaking to a clinician first.