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Mounjaro vs. Orforglipron

30 Sep 2025

7 min read

mounjaro box

Mounjaro and Orforglipron are both weight loss medications that suppress appetite and regulate hunger signals in the brain to help you lose weight. 

Mounjaro is available on prescription right now, and orforglipron is in development and may be available as early as 2026. But which is better for weight loss and which might be right for you? 

In this guide, we’ll explore what both medications are and how they work, as well as when and where you can get them.  

We‘ll also run through the similarities and differences between them so you can decide which might be right for you.  

What is Mounjaro 

Mounjaro is a type of injectable weight loss medication that you take once a week. It’s active ingredient is tirzepatide, which belongs to a group of medications called GLP-1 receptor agonists, commonly shortened to ‘GLP-1s’.

Mounjaro is classed as a ‘dual agonist’ because it mimics two hormones, glucagon‐like peptide‐1 (GLP‐1) and gastric inhibitory polypeptide (GIP).  

What is Orforglipron 

Orforglipron is a weight loss medication that comes in tablet form. It’s in development to treat type 2 diabetes and help with weight loss.

Like Mounjaro, it’s also a GLP-1 agonist, but it doesn’t affect GIP. Orforglipron is in phase 3 clinical trials now and has shown significant results in helping treat obesity and being overweight in patients. 

Administration (injection vs tablet) 

Although they work similarly, Orforglipron and Mounjaro are administered differently.  

Orforglipron (tablet) 

You take Orforglipron by swallowing a tablet with a glass of water once a day with or without food. 

Once the medication hits the market, it’s likely to be ‘titrated’ meaning you’ll gradually increase the dose over time. This is so your body can get used to the medication, minimising side effects. 

Eli Lilly, who manufacture Orforglipron, haven’t yet announced the starting dose or dosing schedule, but it’s likely to be around 12mg, based on the dosage used in clinical trials.

Mounjaro (injection) 

Mounjaro  (tirzepatide) is self-injected once a week, at the same time and on the same day each week. 

The starting dose is 2.5mg, though this may be titrated up to 15mg after you’ve been using it for 17 weeks or more.  

Here are instructions on how to inject Mounjaro.

Mechanisms of action 

With medications, the ‘mechanism of action’ is a fancy way of saying ‘how the drug works in your body’ – in this case, to help you lose weight.  

Orforglipron 

Orforglipron is a type of medicine called a GLP-1 agonist. That just means it works in a similar way to a natural hormone your body already makes. 

Here’s what it does: 

Helps control blood sugar – it tells your pancreas to release more insulin when you need it. 

Slows down digestion – your stomach empties more slowly, so you stay full for longer after meals. 

Reduces cravings – it sends “I’m full” signals to your brain, which can make it easier to eat less. 

Unlike some other GLP-1 medicines (like Mounjaro), Orforglipron is made in a way that means it doesn’t break down in your stomach. That’s why it can be taken as a tablet instead of an injection – good news if you don’t like needles! 

Mounjaro  

The key difference between orforglipron and Mounjaro is that Mounjaro also mimicks the GIP hormone as well as the GLP-1.

GIP stimulates insulin release from the pancreas. This dual action makes Mounjaro highly effective for weight loss.

Effectiveness for weight loss 

Mounjaro 

Mounjaro is considered a very effective weight loss drug.  

In a study of 2,539 people, tirzepatide (Mounjaro) users lost an average of 22.5% of their starting body weight over 72 weeks on a maintenance dose of 15mg a week.

Orforglipron 

Current clinical data shows orfoglipron is also highly effective for weight loss.  

In phase 3 trials, involving 3,127 adults, people taking orforglipron users lost up to 12.4% of their starting weight taking a 36mg daily dose over 72 weeks.   

How fast will I lose weight with Mounjaro?  

Most people taking Mounjaro can expect to lose under 1% per week of their starting weight during the first month of treatment.

Weight loss typically increases over time as the dose increases. By week 13, you may lose up to around 13% of your starting weight.

How long does it take for orforglipron to start working? 

Orforglipron starts working quickly, with most people seeing weight loss in just 4 weeks of treatment.

Side effects 

As with any medication, both Mounjaro and orforglipron can have side effects.  

Like most GLP-1 medicines, the side effects for both are mostly gastrointestinal (affecting your digestive system). 

Does Mounjaro have side effects?

Mounjaro side effects include:

  • constipation  
  • diarrhoea 
  • indigestion 
  • nausea 
  • risk of low blood sugar (hypoglycaemia) 

These side effects tend to be more common when starting treatment, but get better as you get used to the medication. Learn more about how to manage and treat them in our guide to Mounjaro side effects.

Does Orforglipron have side effects? 

Orforglipron side effects include: 

  • constipation 
  • diarrhoea 
  • fatigue 
  • nausea 
  • stomach ache 
  • vomiting 

As with Mounjaro, these side effects tend to occur in the first few weeks and will improve as your body adjusts to the medication.  

Availability and accessibility 

Mounjaro 

Mounjaro is available on prescription if you:

  • are over 18 years old 
  • have a body mass index (BMI) of 30 or higher, or a BMI between 27 and 30 and you have a weight-related medical condition  
  • are not taking any medications, or living with any medical conditions, that would make it unsafe to use Mounjaro 
  • are not allergic to any of the ingredients in Mounjaro 

To see if you’re eligible for Mounjaro treatment, you can start a consultation with one of our expert prescribers here.

Orforglipron 

Orforglipron is not yet available, so we don’t know the exact prescription criteria yet. Orforglipron has an estimated launch date of 2026. 

Is Mounjaro licensed for weight loss? 

Yes, Mounjaro has been licensed for weight loss since November 2023.

Is Orforglipron licensed for weight loss?  

No, orforglipron is not currently licensed for weight loss.  

But its manufacturer, Eli Lilly, is seeking approval from the U.S. Food and Drug Administration (FDA) who regulate all medicines, and are hoping to have orforglipron licensed for sale by late 2026 or early 2027. 

Where will I be able to buy orforglipron?  

ou cannot buy orforglipron. It is currently in clinical trials and if it is licensed for weight loss, you’ll need to qualify and undergo a consultation with a private clinic or your healthcare provider. 

Conclusion 

Mounjaro and Orforglipron are similar medications. However, they’re administered differently and work differently inside the body. This will affect which one is more suitable for you.  

You may prefer Orforglipron if you’d rather take a tablet than use a needle and enjoy the flexibility of not needing to schedule a specific time to do so.  

At the end of the day, your prescriber will help you find the best treatment for your needs. 

Key points of article  

  • Orforglipron is a GLP-1 weight loss medication tablet currently in development, which the manufacturers hope to have licensed for sale by late 2026. 
  • Mounjaro is an injectable weight loss medication currently available on prescription for people with a BMI of 30 or more, or 27 if you have a weight-related health condition. 
  • Both medications have been shown in clinical trials to be effective for weight loss, and the best medication for you depends on a number of factors and your personal preference. Talk to your prescriber about your options.  

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