Mounjaro vs Wegovy vs Foundayo: Which weight loss medication is best?

The new weight loss medication entering the market, Foundayo, has been described as game-changing. Foundayo (orforglipron) is a synthetic version of the natural hormone in the body called glucagon-like peptide-1 (GLP-1). GLP-1, produced by the gut, is released after eating and plays a key role in controlling appetite, blood sugar levels, and weight loss.

In April 2026, Foundayo was approved by the Emirates Drug Establishment (EDE) and the U.S. Food and Drug Administration (FDA). It’s already available by prescription in the US and is expected to become available to eligible patients in the UAE in May 2026.

With the medication predicted to gain approval in the UK later this year, many patients are wondering how it compares to other big-hitters, Wegovy (semaglutide) and Mounjaro (tirzepatide). In this blog, we’ll explore how Foundayo differs from Mounjaro and Wegovy, including ease of use, side effects, pricing, and effectiveness. 

How do you use each weight loss medication?

Below are instructions for the application of Mounjaro, Wegovy and Foundayo, which are all designed to support weight loss alongside lifestyle changes. However, it’s important to take medication as your healthcare provider advises.

Mounjaro and Wegovy applications

Mounjaro and Wegovy are both available as pre-filled, injectable pens that must be taken once weekly on the same day each week, with or without food. The suggested injection sites are the stomach, thigh, and upper arm. It’s advised to inject one finger width away from the last injection placement to minimise irritation.

A once-daily tablet form of Wegovy was also recently approved by the US FDA, in which patients take it on an empty stomach 30 minutes before food or drink. However, Wegovy tablets are not currently licensed in the UK.

Foundayo application

A key difference with Foundayo is that, unlike Wegovy and Mounjaro, it’s not an injectable medication. Instead, it comes as a tablet that is taken once daily, with or without food. Users should swallow the tablet whole, and do not break, crush or chew. If a dose is missed, it’s advised to take it as soon as possible, but not to take more than one tablet per day.

If users miss Foundayo doses for seven or more days in a row, they must contact their healthcare provider to discuss how to best restart the treatment. Seek immediate medical attention after taking too much Foundayo.

Who is eligible for weight loss medication?

It’s important to seek specialised advice from your healthcare provider to find out if weight loss medication is suitable for you. We offer a no-commitment assessment to see if you’re eligible for weight loss medication.

Mounjaro and Wegovy eligibility criteria

National Institute for Health and Care Excellence (NICE) recommends Mounjaro or Wegovy for the management of obesity in certain patients. It’s ideal for individuals who have struggled with conventional weight loss techniques and need further assistance.

These treatments are commonly recommended for adults with a body mass index (BMI) of 30 or more, or those with a BMI of 27 or above and who also have weight-related health issues, such as dyslipidaemia (abnormal fat levels in the blood), hypertension (high blood pressure), and type 2 diabetes.

While semaglutide is also sold under the name Ozempic, Wegovy is specifically approved by the Medicines and Healthcare products Regulatory Agency (MHRA) for weight loss in the UK, whereas Ozempic is approved for treating type 2 diabetes.

However, Mounjaro and Wegovy aren’t suitable for everyone. Below are several people who should NOT take it:

• People with type 1 diabetes
• People with a history of pancreatitis (inflammation of the pancreas)
• People with Medullary Thyroid Cancer (MTC) or Multiple Endocrine Neoplasia type 2 (MEN 2)
• Pregnant or breastfeeding women
• People with severe gastrointestinal issues (like gastroparesis)
• People on certain medications (e.g., insulin, other GLP-1s, the contraceptive pill)
• People who are allergic to any ingredients in the medication

It’s also important to note that your body may not absorb the contraceptive pill while using Mounjaro, and additional methods of contraception may be required. Alternatively, Wegovy or another weight loss medication may be more suitably paired with the contraceptive pill.

Foundayo eligibility criteria

Similar to the Mounjaro and Wegovy eligibility, Foundayo is currently available to adults (18 years and over), with a body mass index (BMI) of 30 or above, or a BMI of 27 or above with at least one related health condition (e.g., type 2 diabetes, high cholesterol). However, Foundayo is only currently available to patients in the USA and the UAE. 

The same criteria for who should not take Foundayo are the same as those for Mounjaro and Wegovy. However, Foundayo is more accessible to those with a fear of needles.

What are the dosage schedules for each weight loss drug?

The doses typically follow a set schedule, depending on how each patient reacts to the treatments. However, it’s important to only ever change the dose of your weight loss medication under medical advice and to consult your doctor as soon as possible if you can’t tolerate your new dose due to new side effects. 

Mounjaro doses

You’ll typically start with a dose of 2.5 mg for the first 4 weeks, and depending on how your body responds, increase to:

• 5 mg from week 5 to week 8 (maintenance dose)
• 7.5 mg from week 9 to 12
• 10 mg from week 13 to week 16 (maintenance dose)
• 12.5 mg from week 17 to week 20
• 15mg (maximum) 

Patients may not need to increase to all of these doses, and can take Mounjaro for as long as their doctor prescribes it, which is usually until the weight loss goal is achieved.

Wegovy doses

The starting dose of Wegovy is usually 0.25mg for the first four weeks, before increasing to:

• 0.5mg from week 5 to week 8 
• 1mg from week 9 to week 12
• 1.7mg from week 13 to week 16
• 2.4mg (maintenance dose)

Patients can increase the dose further until it reaches 7.2mg, but it will not be increased any further. 

Foundayo doses

Unlike Mounjaro and Wegovy, the dose increase of Foundayo happens over 30 days, rather than four weeks. The Foundayo dosage schedule is as follows:

• Start at 0.8mg for at least 30 days
• Increase to 2.5mg for at least 30 days
• Move to a 5.5mg dose for at least 30 days

The dosage may then increase further to 9mg, 14.5mg, and then to the maximum of 17.2mg, depending on each patient’s requirements and suitability.

Which weight loss drug is most effective?

To maximise the weight loss results, it’s still vital to follow a good diet, exercise routine, and sleep schedule, as well as minimise alcohol intake and manage stress. 

Mounjaro and Wegovy effectiveness

A clinical trial taken over 72 weeks and published in the New England Journal of Medicine found that 32% of people lost a quarter of their body weight on Mounjaro, compared to 16% on Wegovy. These results suggest that Mounjaro is twice as effective at weight loss as Wegovy. The participants on Mounjaro also lost an average of 18cm from their waistlines, while those on Wegovy lost 13cm.

However, on the highest maintenance dose of Wegovy (7.2mg), patients lost an average of 21% of their starting weight after 72 weeks, and those on the highest Mounjaro maintenance dose (15mg) lost up to 22.5%.

Some may experience small weight changes in the first 4 to 6 weeks of taking weight loss medication, but it can take up to 12 weeks to see any significant changes. The optimal dosage for weight loss also differs across patients, and some may find one medication option more suitable and effective than the other.

Foundayo effectiveness

A clinical trial called ATTAIN-1 that tested how well Foundayo worked for weight management after 72 weeks found that participants lost between 7.7% and 12.4% of their body weight on average. Additionally, nearly 60% of participants taking the highest dose lost at least 10% of their body weight, and just under 40% lost at least 15% of their body weight.

What are the side effects of weight loss medication?

GLP-1 medication side effects are most likely to occur when you first begin treatment and increase doses, so it’s important to maintain a healthy lifestyle. The severity of the side effects can differ across patients.

All three weight loss treatments can cause very similar side effects, including but not limited to:

• Stomach (abdominal) pain
• Hair loss
• Development of gallstones
• Lightheadedness
• Dizziness
• Constipation
• Vomiting
• Nausea
• Diarrhoea
• Fatigue
• Headache
• Acid reflux
• Heartburn
• Indigestion

In the New England Journal of Medicine clinical study, between 77% and 79% of participants reported experiencing at least one side effect from taking either Mounjaro or Wegovy. The study reported that the most common adverse events with both treatments were gastrointestinal, of which most were mild to moderate in severity, and primarily occurred during dose increases.

It’s important to talk to your healthcare provider about any side effects that bother you or don’t go away.

Serious side effects can occur in rare cases, such as:

• Severe stomach problems
• Dehydration that leads to kidney problems
• Inflammation of the pancreas (pancreatitis)
• Low blood sugar (hypoglycemia)
• Gallbladder problems

Foundayo may cause tumours in the thyroid. It’s important to look out for and speak to your medical provider about symptoms such as a lump or swelling in the neck, hoarseness, trouble swallowing, and shortness of breath.

What are the price differences?

Wegovy prices start at approximately £120 for a single pen of 0.25mg strength, with the highest dose of 2.4mg reaching £225 per pen.

The Mounjaro weight loss injection prices start at £149.99 for 2.5mg and go up to £294.99 per pen for a 15mg strength.

While the UK prices for Foundayo are yet to be determined, the medication is available in the US, where it’s reported to cost between $159 to $349 per month for self-pay patients. When converted to GBP at the time of writing, this comes to £117 to £258, making it more in line with the Wegovy pricing. 

Can you switch between weight loss medications?

As the side effects and results vary a lot across patients, some may choose to try a different weight loss treatment to find a more suitable option. Some patients may also receive advice to switch for medical reasons, or if there are limited availability issues with the medication.

Switching between any weight loss medications must be done with the right healthcare supervision, so they can advise on safe timing, dose adjustments, and managing progress.

Mounjaro, Wegovy, and Foundayo all have similar weight loss effectiveness and possible side effects, but the difference lies with each patient. While some may see better results from one medication, another patient may have a completely different experience. Foundayo may provide the biggest relief for people with fears of injections, providing a more comfortable option. However, for advice on which weight loss medication is most suitable for you, seek advice from a medical professional.

Ashcroft Pharmacy can support your weight loss journey with a wide range of treatments. Start your assessment for a comprehensive evaluation of the best weight loss treatment for your needs.