Foundayo vs Mounjaro: How Does the New Weight Loss Pill Compare?

Mounjaro (tirzepatide) and Foundayo (orforglipron) are two weight loss medications that belong to the glucagon-like peptide 1 (GLP-1) agonist family. Mounjaro is taken as an injection, while Foundayo is a daily tablet.

While Mounjaro has been sold in the UK since 2024 for treating type 2 diabetes and to support weight loss, Foundayo is not yet available in the UK. The UK Medicines and Healthcare products Regulatory Agency is currently assessing Foundayo to see if they will license it for use in the UK. Foundayo is already available in the US.

Both Mounjaro and Foundayo can help people to lose weight, but they’re taken in different ways, and one is typically more effective for weight loss than the other.

In this article, we’ll explore the two different medications, including how they work, their similarities and differences, how much weight you can expect to lose with Foundayo vs Mounjaro, and which medication is better for who.

Foundayo vs Mounjaro: Pill vs injection

One of the biggest differences between orforglipron (brand name Foundayo) and tirzepatide (brand name Mounjaro) is how they’re taken.

Mounjaro is taken as a once-weekly injection that’s administered just underneath the skin. The medication comes in an automatic injection device known as a KwikPen which helps you take the injection without needing to use a needle and syringe or work out how much liquid to inject.

Each pen device has a pre-set dose strength: 2.5, 5, 7.5, 10, 12.5, or 15mg. The KwikPen contains enough medication for four of these doses, with one dose taken each week. After the 4-week period is over and you’ve taken all four doses, you’ll need a new a pen either at the same dose or the next dose up if you’re still getting to your maintenance dose.

With Foundayo, the process is simpler. You take a daily tablet orforglipron at your specific dose. You’ll start at the lowest dose of 0.8mg daily and continue at this strength for at least 30 days. At this point, you can increase up to the next dose of 2.5mg.

You can continue to increase your orforglipron tablet dose every 30 days up to a maximum of 17.2mg daily.

Orforglipron (Foundayo) tablets should be swallowed whole and not crushed or chewed. You can take them with or without food.

How they work differently

Both medications belong to the same family of medications called GLP-1 agonists. This means they both work similarly to the natural hunger hormone GLP-1, activating the GLP-1 receptors and making the body think levels of the hormone are high.

The body responds by slowing down how fast the stomach empties, regulating blood sugar levels, and quietening hunger cues in the brain. Together, these actions help make it easier to eat less food and lose weight. The activity also means they’re useful for managing type 2 diabetes.

However, for either medication to be effective, you’ll need to eat a balanced, reduced calorie diet and exercise regularly.

Mounjaro is slightly different to Foundayo as it works on two receptors rather than one. It also activates the receptors of another gut hormone called glucose-dependent insulinotropic polypeptide (GIP). This helps to improve insulin sensitivity and impacts fat storage/metabolism.

Weight loss expectations

Both Mounjaro and Foundayo can support people to lose a significant amount of weight, but more is lost with Mounjaro, on average. In clinical trials, either medication helped people lose a greater amount of weight than making lifestyle changes alone.

Weight loss expectations with Mounjaro

After taking Mounjaro or a placebo (non-active) injection for 72 weeks, people taking the highest 15mg dose of Mounjaro lost an average 20.8% of their bodyweight compared to just 3.1% in people taking the placebo.

Even if taking a lower 5mg maintenance dose of Mounjaro, 85% of people lost at least 5% of their bodyweight compared to 35% of people receiving the placebo. At the highest Mounjaro dose, 57% of people lost 20% or more of their bodyweight compared to 3% in the placebo group.

Weight loss expectations with Foundayo

Clinical trials found that orforglipron helped people lose weight, but typically not as much as with Mounjaro.

After taking the highest 36mg dose of orforglipron for 72 weeks, individuals lost an average 11.2% of their starting bodyweight vs 2.1% for people taking the placebo.

Of patients taking the highest 36mg dose of Foundayo, 18.4% lost at least 20% of their bodyweight compared to 2.8% of the placebo group.

It’s important to remember that weight loss results vary from person to person. Some people will lose more than the average and others will lose less.

Side effect comparison

The side effects of both medications are similar as they belong to the same drug family. Injection site reactions can only happen with Mounjaro as it’s injected, while orforglipron may be slightly more likely to cause digestive side effects as it’s taken as a tablet.

Gastrointestinal side effects tend to be the most common side effects when taking either medication. These include:

• Nausea/vomiting

• Constipation

• Diarrhoea

• Heart burn/acid reflux

• Abdominal pain

• Bloating

• Burping or passing wind

Around 60-69% of patients taking orforglipron experience gastrointestinal side effects vs 37% of people taking placebo tablets, and 8% of people taking the highest dose stop the medication due to these side effects.

Gastrointestinal side effects impact 55.6% of people on the highest dose of Mounjaro compared to 29.7% taking the placebo, and 4.3% stop taking the medication because of this.

Other common side effects of orforglipron are headaches, fatigue, and/or hair loss. Common Mounjaro side effects include hypersensitivity, dizziness, low blood pressure, gallstones, fatigue, and/or abnormal blood test results.

Serious side effects of either medication are rarer but can include:

• Allergic reactions with swelling affecting the face and airway – this requires emergency medical attention

• Low blood sugar – especially in people taking other medication for type 2 diabetes

• Pancreatitis – inflammation of the pancreas

• Gallbladder problems – inflammation and/or gallstones

• Acute kidney problems – often due to vomiting or diarrhoea caused by the drug

• Worsening of diabetic retinopathy

• Thyroid tumours – listed as a possible side effect due to findings in rodent studies, not humans

• Increased risk during surgery with general anaesthesia

A full list of all the side effects for each medication is available in the patient information leaflet found inside the drug packaging.

Convenience and lifestyle

Many people would prefer to take a tablet rather than an injection which means Foundayo may be more convenient for them.

Mounjaro is taken as injection which most people find more uncomfortable. The Mounjaro pens have specific storage instructions around temperature (especially before they’re opened), how long they can stay open for and still be effective for use, and contain needles that need to be safely disposed of.

Taking a daily tablet is easier for many people as they don’t have to worry about storage or needle disposal. However, some people may find it difficult to remember to take their tablet every day and may find a weekly injection more manageable.

Foundayo can be taken with or without food which makes it even more convenient when compared to other weight loss tablets like Wegovy that can only be taken on an empty stomach.

Who may prefer which

Which medication you prefer is a personal choice and depends on your goals and lifestyle.

Mounjaro leads to more weight loss, on average, but also requires a weekly injection while Foundayo is usually much more convenient and easier to take.

While Foundayo may not offer the same weight loss results you can typically expect with Mounjaro, more research is being done into using the drug for weight maintenance. This may mean taking a weight loss injection to get to your goal weight, then taking Foundayo tablets to maintain that weight.

A recent clinical trial found that orforglipron was effective at preventing weight regain after stopping weight loss injections. People taking orforglipron after stopping Mounjaro maintained 74.7% of the weight they’d lost compared to 49.2% with a placebo tablet.

Once Foundayo is approved in the UK, it could be a good option for people who’ve reached their target weight with Mounjaro but want a more convenient maintenance medication.

In the meantime, book an online weight loss consultation with Quick Meds to learn more about the weight loss medications currently available and which is the most suitable for you.