Foundayo (Orforglipron) vs Mounjaro

Medicated weight loss programmes have been clinically proven to help people overcome obesity when dieting and exercising alone weren’t having the desired effect. However, over a longer period, subcutaneous injections have achieved greater results, with Mounjaro (tirzepatide) leading the way. Although oral tablets existed, their mechanisms of action didn’t yield the same success, meaning people who didn’t like the idea of having to inject themselves could have been put off.

This changed in June 2026, when the Medicines and Healthcare products Regulatory Agency (MHRA) approved oral semaglutide (also known as the Wegovy pill) for weight loss, making it the first GLP-1 treatment to be licensed for this purpose. We’ve compared Wegovy pills vs Mounjaro in a special article on your website if you’d like to read more.

Just two months later, the regulator approved Foundayo (orforglipron), another oral GLP-1 medication manufactured by Lilly, which also makes Mounjaro. But how does this new treatment compare to its injectable counterpart?

Join us as we compare Foundayo (orforglipron) vs Mounjaro, looking at similarities and differences, potential weight loss results, side effects, and more. Let’s get started. 

What are Orforglipron (Foundayo) and Tirzepatide (Mounjaro)? 

Orforglipron (Foundayo) and Tirzepatide (Mounjaro) are both GLP-1 medications, a class of drugs developed to treat obesity and type 2 diabetes. They work by mimicking the effects of a hormone naturally released from the gut after eating, which influences both digestive function and blood sugar control.

GLP-1 drugs slow gastric emptying (the rate at which food moves through the stomach), making users feel fuller more quickly. They also activate a brain region that reduces the ‘reward’ associated with eating, further suppressing appetite and ‘food noise.’ This often leads to a significant reduction in food intake and, therefore, weight loss.

Orforglipron and Mounjaro also enhance insulin secretion, which facilitates the movement of glucose molecules from the bloodstream into cells. Therefore, they help to regulate blood sugar and can improve glycemic control in people with type 2 diabetes. Other potential health benefits of GLP-1 medications include:

• Lower triglyceride levels
• Reduced LDL cholesterol levels
• Improved cardiovascular health
• Improved kidney health
• Lower blood pressure
• Better body composition
• Reduced risk of stroke

What is the Difference Between Foundayo and Mounjaro?

Foundayo and Mounjaro both belong to a class of medications that target GLP-1 receptors. However, their structures and mechanisms of action are different. Mounjaro is a peptide-based medication composed of a chain of 39 amino acids. Its structure mimics that of the GLP-1 and GIP hormones released from the small intestine, which influence digestive function to reduce appetite and food intake. ​

Orforglipron is a small-molecule GLP-1 receptor agonist. Rather than mimicking the structure of GLP-1, it binds directly to the GLP-1 receptor. This activates a signalling pathway that stimulates insulin secretion, regulates blood sugar, and slows gastric emptying, which reduces appetite.

Foundayo and Mounjaro also differ in their administration methods. Like most other GLP-1 medications, Mounjaro comes as a liquid that users inject weekly. Orforglipron is a daily, oral medication that comes in pill form.

Are There Any Similarities Between Foundayo and Mounjaro?

Foundayo and Mounjaro both target the GLP-1 pathway, which regulates both appetite and blood glucose levels. As a result, users of both medications are likely to experience similar effects, including weight loss and improved glycemic control. The side effects of these medications are also similar and mostly affect the digestive system, commonly causing nausea, vomiting, and diarrhoea.

Foundayo is a daily oral medication, whereas Mounjaro is a weekly injection. However, both drugs follow a gradually escalating dosing schedule. Foundayo users must stay at each dose level for at least 30 days before titrating up, while Mounjaro doses can be increased every four weeks. The effects of both medications are dose-dependent, with higher doses typically producing the greatest weight loss results.

Foundayo vs Mounjaro Weight Loss Results

Foundayo and Mounjaro can both help users ‌lose a substantial amount of weight by reducing appetite, increasing satiety, and cutting ‘food noise.’ However, tirzepatide users may lose more weight than those on Foundayo.

A clinical trial examining the effects of orforglipron (the active ingredient in Foundayo) found that participants on the highest dose lost an average of 12.4% of their starting weight over 72 weeks of treatment. Of the 1,127 participants who had prediabetes at the start of the study, 91% of those taking Foundayo had achieved near-normal blood sugar levels by the end. Orforglipron treatment was also beneficial for cardiovascular health and improved non-HDL cholesterol levels, systolic blood pressure, and triglyceride levels.

​A similar study into the effects of tirzepatide found that people using the weight loss injection lost 16- 22.5% of their body weight after 72 weeks. Like orforglipron, tirzepatide also has significant health benefits and can improve glycemic control, blood pressure, cholesterol, and triglyceride levels.

​Both Foundayo and Mounjaro can promote significant weight loss and improvements in other key health markers. However, tirzepatide is more potent as a weight loss aid because it activates two receptors (GLP-1 and GIP). This makes tirzepatide’s effects on appetite and food intake stronger than those of orforglipron, which only activates one receptor (GLP-1).

Side Effects of Foundayo Compared to Mounjaro

Foundayo and Mounjaro have a very similar side effect profile. Like all GLP-1s, both medications frequently cause gastrointestinal symptoms including nausea, vomiting, diarrhoea, and constipation. Both Foundayo and Mounjaro also have the potential to cause rarer and more serious health conditions such as acute pancreatitis, gallstones, and kidney damage (brought about by severe dehydration from vomiting and diarrhoea).

With both medications, the side effects are dose-dependent and typically increase in severity around dose escalations and at the start of treatment. Most side effects are mild to moderate, but they can be uncomfortable enough for some people to discontinue treatment. Foundayo produced relatively high discontinuation rates in clinical trials, with most users citing gastrointestinal side effects as their reason for stopping treatment.

​Gastrointestinal symptoms may be more prevalent with Foundayo than Mounjaro, with the ATTAIN-1 clinical trial reporting nausea in over 33% of people taking the highest dose of orforglipron. Diarrhoea was reported in around 23% of participants on this dose, and vomiting affected 24% of users.

​A different study of tirzepatide users found that 12-24% experienced nausea, 12-22% had diarrhoea, and 2-13% reported vomiting. Another study of people who switched from tirzepatide and other GLP-1 injections to orforglipron found that up to 7.3% discontinued treatment due to side effects. No head-to-head trial data currently exist on the side effects of orforglipron vs tirzepatide.

You can find out more about the side effects of Mounjaro and how long they last by reading our dedicated articles.

Orforglipron vs Tirzepatide Dosage Schedules

Orforglipron and tirzepatide follow gradually escalating dosing schedules. Users of both medications start with a low dose (sometimes called an initiation dose), which they can increase at intervals throughout their treatment.

​Orforglipron users would start with a daily dose of 0.8 mg, increasing through 2.5 mg, 5.5 mg, 9 mg, 14.5 mg, and 17.2 mg. People taking tirzepatide begin treatment with a once-weekly injection of 2.5 mg, escalating through 5 mg, 7.5 mg, 10 mg, 12.5 mg, and 15 mg. More information regarding the Mounjaro dosage schedule is available on our website. 

​For both medications, users must stay at each dose level for a minimum of 1 month with orforglipron and 4 weeks with tirzepatide. This slow increase in dosage allows your body to get used to the medication and may help to reduce the risk of gastrointestinal side effects.

Can You Switch from Mounjaro to Foundayo?

You can switch from Mounjaro to Foundayo, and some experts suggest it may help with weight maintenance. Weight regain is very common among people who stop using tirzepatide, and it can happen rapidly. One study found that people gained an average of 0.8 kg (1.8 lbs) per month after discontinuing Mounjaro, with implications for their cardiovascular and metabolic health.

One potential solution is to switch to Foundayo once you have achieved your weight loss goals with Mounjaro. Research into this scenario found that participants successfully maintained most of their weight loss with orforglipron treatment, and were better able to do so than those who quit GLP-1s altogether.

​Another possible reason to swap Mounjaro for Foundayo is to avoid the need for self-injection. Like many other GLP-1 treatments, Mounjaro is a liquid medication that users inject under the skin. Foundayo is a daily, oral medication available in pill form. Therefore, some users may want to switch to Foundayo for its comparative ease of use.

​If you want to switch to a different GLP-1 therapy, do so only under the supervision of a healthcare professional. Reach out to your prescribing clinician to discuss your options and for advice on safely switching from Mounjaro to Foundayo.

Will Orforglipron be Cheaper than Mounjaro?

It’s not yet clear whether Foundayo (orforglipron) will be cheaper than Mounjaro. This won’t be known until Foundayo becomes available in the UK and prices can be fully compared. Several factors can dictate the cost of a new medication, including distribution costs and dosage strength. 

Foundayo vs Mounjaro: Which is Better?

Deciding what’s better between Foundayo vs Mounjaro ultimately comes down to personal preference and what’s best for your circumstances. Everyone’s weight loss journey is different, so there’s no universal answer. It comes down to whether you prioritise weight-loss effectiveness, method of administration, treatment schedule, or how well a treatment fits your routine. Existing medical conditions and treatments you’re currently taking may also play a part. A clinician or doctor will be able to help you determine the right course of action for you. 

Frequently Asked Questions

The MHRA recently approved Foundayo (orforglipron) for prescription in the UK, and this authorisation has led many people to consider the benefits of weight loss pills.

Here, we’ll cover some of the most commonly asked questions about orforglipron, tirzepatide, and whether you can take these two medications simultaneously.

Can You Take Orforglipron and Mounjaro Together?

You can’t take orforglipron and Mounjaro together. The manufacturer, Eli Lilly, explicitly states in their Foundayo medication guide that this medication should not be used in combination with any other GLP-1 therapies.

​Foundayo and Mounjaro both work on the GLP-1 receptor, so taking both at the same time could significantly increase your risk of gastrointestinal side effects. If you want to increase the effectiveness of your weight-loss treatment, speak with your prescribing clinician about increasing your dose or switching to a different medication.

Is Orforglipron the Same as Tirzepatide?

Orforglipron and tirzepatide both target the GLP-1 pathway, but they are not the same drug. Tirzepatide is a weekly, injectable, peptide-based medication that works by mimicking the structure of GLP-1 and GIP. Orforglipron is a daily, oral small-molecule medication that binds directly to the GLP-1 receptor.

Both medications can suppress appetite and reduce food intake by slowing gastric emptying and targeting brain regions that increase satiety. However, their mechanisms of action and administration are different. They may also have different levels of efficacy, with clinical studies showing that tirzepatide produces more weight loss than orforglipron.

Reliable Support Throughout Your Journey

Losing weight can seem daunting, especially if you’ve tried before without much success. However, this isn’t a journey that you have to go through alone, as Prescription Doctor is here to help.

Since 2013, we’ve supported countless individuals in achieving their goals, and we’re ready to do the same for you. In addition to comparisons between Orforglipron vs Mounjaro, we provide essential information on side effects, dosing schedules, and weight loss potential for the medications we offer, so you can better understand how they work.  

Our experienced clinicians are also available to guide you whenever you have a query about your treatment and will regularly check in with you to monitor progress. It’s all part of our holistic service.

With us, there’s no need for an appointment. Just a straightforward and secure online process that you can complete at any time from the comfort of your home. Simply fill out a brief questionnaire, and our clinicians will determine if your chosen medication is suitable for your circumstances. Approved orders are dispatched by our General Pharmaceutical Council-registered pharmacy in plain packaging for complete discretion, and orders approved before 3pm on a weekday are also eligible for next-day delivery.

If you’re looking for specialist support with your weight loss journey, you’ve got it with Prescription Doctor. 

Authored By

Kate Latham

Medical Content Writer

Kate has been a scientific content writer since 2017. With a BSc in Biology and a background in cancer research, she is adept at identifying the latest findings in medical research and utilising these

Published on: 24/08/2026

Reviewed By

Mohamed Imran Lakhi

MPharm - Lead Pharmacist

Imran Lakhi is the superintendent pharmacist and founder at Prescription Doctor. He has been at the core of our team.

Reviewed on: 24/08/2026