Weight loss injections vs tablets

Weight loss treatments come in two main forms: injections and tablets, and each has its own strengths depending on your lifestyle, goals, and preferences. You’ve likely heard of popular options like Wegovy and Mounjaro injections, while Wegovy tablets are currently being reviewed for use in Ireland.

So, whether you're just starting to think about trying a medicated weight loss treatment or you've been doing your research for a while, you're probably wondering which type is right for you.

In this guide, we'll walk you through everything you need to know about weight loss injections and tablets, so you can make a confident, informed decision.

Key points

• Weight loss injections tended to produce greater average weight loss in clinical trials, but tablets may be a more convenient option for people who don't want to self-inject.
• Both injections and tablets are prescription-only treatments (except for lower-dose orlistat), and you'll need to meet eligibility criteria before starting.
• Wegovy tablets and Foundayo aren't available in Ireland yet, but licensed alternative options are available right now if you're ready to start your journey.

Weight loss injections and tablets at a glance

What’s the difference between weight loss injections and tablets?

Both injections and tablets can help you lose weight, but they're not all the same. They differ in how they work, how you take them, and how much weight loss you can expect. Here's what you need to know.

How they work

Most weight loss injections, like Wegovy and Mounjaro, and some tablets, like Wegovy tablets and Foundayo, work in the same way, by mimicking a hormone called GLP-1 that your body naturally produces after eating.

This hormone helps to:

• regulate your appetite
• make you feel fuller for longer
• slow down how quickly your stomach empties

Mounjaro, however, goes a step further than GLP-1-only drugs because it also activates the GIP receptor. This dual action is one reason why tirzepatide has shown greater average weight loss than semaglutide in clinical trials.

Not all tablets work this way, though. Orlistat works in your gut rather than your brain, blocking around a third of the fat you eat from being absorbed. Mysimba works differently again, targeting the parts of the brain that control hunger and cravings.

“While it's tempting to compare injections and tablets side by side, it's important to know that some treatments do completely different jobs inside your body.

“This plays a part in how effective they are, potential side effects, and if they're suitable for you personally."

Ayesha Bashir, weight loss expert at myBMI

How you take them

This is one of the biggest practical differences between injections and tablets, and it's an important factor to consider when making your decision.

Most injections are given once a week using a pre-filled pen, injected into the skin on your stomach, thigh, or upper arm. Liraglutide injections, like Saxenda, are the exception, as they’re taken daily.

Many people find the process more straightforward than they expected, but if the idea of self-injecting isn't for you, that's something to keep in mind.

Tablets are taken daily. Wegovy tablets and Rybelsus need to be taken first thing in the morning on an empty stomach, with no more than 120ml of plain water, with a 30-minute wait before eating, drinking, or taking other medications.

During clinical trials, Foundayo was taken differently. Because it's a small-molecule, non-peptide medicine, your body can absorb it through the gut without any special conditions, meaning it can be taken at any time of day with or without food.

For Mysimba, it’s 1-4 tablets per day, depending on which week of treatment you're in, with your dose gradually increasing over the first month. Orlistat is taken 3 times a day, just before, during, or up to an hour after each main meal. This means that you need to stay consistent with your timings throughout the day.

Effectiveness

In clinical trials, injections have generally produced greater average weight loss than tablets.

Mounjaro produced average weight loss of 22.5%, with Wegovy injections at around 21% at the highest available 7.2mg dose.

Wegovy tablets were studied in the OASIS trial and achieved around 14% average weight loss over 64 weeks. Foundayo showed around 11% average weight loss over 72 weeks in the ATTAIN-1 trial. Older options like orlistat and Mysimba tend to sit in the 5-10% range.

It's important to remember that these are averages from clinical trial settings, and individual results vary.

Some people lose more, some lose less, and factors like diet, activity levels, and how long you stay on the treatment all make a difference.

A treatment that produces 14% average weight loss is still clinically meaningful, and for many people, the convenience of a tablet outweighs that difference.

Active ingredients

Here's a quick summary of what's in each treatment:

• Mounjaro contains tirzepatide (a GLP-1 and GIP receptor agonist)
• Wegovy injections, Wegovy tablets, and Rybelsus all contain semaglutide (a GLP-1 receptor agonist)
• Saxenda contains liraglutide (a GLP-1 receptor agonist)
• Foundayo contains orforglipron, a newer small-molecule GLP-1 receptor agonist
• Mysimba contains naltrexone and bupropion
• Alli, Orlos, and Xenical contain orlistat

Side effects

Because many of these treatments work in similar ways, the side effects are often quite similar, too. These are usually worse when you first start or when your dose increases, and they tend to settle down as your body adjusts.

The most common side effects across GLP-1 treatments include:

• nausea
• vomiting
• diarrhoea
• constipation
• stomach discomfort

Injections can sometimes cause mild reactions at the injection site, like redness or irritation. You won't get that with tablets.

Orlistat has its own set of side effects, mainly affecting digestion, like:

• oily or fatty stools
• needing the toilet urgently
• more frequent bowel movements
• wind and stomach pain

These are more likely if you eat a high-fat meal while taking it.

Mysimba's most commonly reported side effects may include:

• nausea
• headaches
• constipation
• dry mouth
• insomnia
• dizziness

Side effects don't affect everyone, and most people find them manageable. Your prescriber will be able to help if you're struggling.

Price

The price of weight loss treatments differs depending on your chosen treatment and pharmacist. This is in part because injections and tablets have different manufacturing and shipping costs.

Wegovy tablets and Foundayo don't have confirmed pricing yet. Once Wegovy tablets launch, the price will be set by Novo Nordisk, and the same applies to Foundayo, but with Eli Lilly.

In both cases, private prescription costs will vary by provider. We'll update this page as soon as our official pricing is available.

Eligibility and availability

Eligibility varies depending on which treatment you're looking at, but most prescription weight loss treatments share a similar framework. For injections like Mounjaro, Wegovy, and Saxenda, and for tablets like Mysimba, you'll typically need:

• a BMI of 30 or above, or
• a BMI of 27 or above, alongside at least 1 weight-related health condition, like type 2 diabetes, high blood pressure, or high cholesterol

Rybelsus is licensed for type 2 diabetes rather than weight loss, so if it's prescribed for weight management it's considered off-label use. This is common, safe, and legal, but it's only appropriate if your prescriber decides it's the right option for you.

Orlistat has slightly different criteria depending on the dose. Prescription orlistat 120mg (Xenical) is generally available to people with a BMI of 30 or above, or 28 or above alongside a weight-related health condition.

Meanwhile, over-the-counter orlistat 60mg (Alli, Orlos) is typically suitable for adults with a BMI of 28 or above, and is the only weight loss treatment you can buy without a prescription.

We don't yet know the eligibility criteria for Wegovy tablets and Foundayo, as neither has been approved in Ireland yet. We'll update this page as soon as more information is available.

Before starting any prescription treatment, you'll need to complete a consultation with a prescriber who'll review your medical history and make sure the medication is safe and suitable for you.

Can you switch from weight loss injections to tablets?

“Yes, it's possible to switch from injections to tablets, and there are a few reasons why you might want to, like a preference for a needle-free routine or wanting to try a different treatment.

“It's not something you should do on your own, however. Any change to your treatment should be discussed with your prescriber, who can guide you on timing, dosing, and what to expect during the transition.”

Ayesha Bashir, weight loss expert at myBMI

Frequently asked questions about weight loss injections vs tablets

What’s the most effective weight loss treatment?

Based on clinical trial data only, Mounjaro currently produces the highest average weight loss of any licensed treatment, at around 22.5% over 72 weeks. Wegovy injections are close behind at around 21%. That said, the most effective treatment for you personally depends on your eligibility, your health history, and how well you tolerate it.

Do weight loss tablets actually work?

Yes, they do. The newer GLP-1 tablets like Wegovy tablets and Foundayo have shown meaningful weight loss in large clinical trials. Older tablets like orlistat and Mysimba tend to produce more modest results, but they can still be effective as part of a broader weight management plan.

What’s the strongest prescription weight loss pill?

There is no strongest pill, as weight loss depends on many personal factors, including how you respond to the treatment and the other lifestyle changes you make. Among tablets currently available or coming soon, Wegovy tablets (25mg) showed the highest average weight loss in clinical trials at around 14%.

In terms of what’s available now, Mysimba and orlistat showed similar results at around 5-10% weight loss, and with Rybelsus, patients lost an average of 8 pounds in 6 months.

However, it’s important to note that clinical trial data doesn't always represent real-world performance, and that this guide is for information purposes only.

Summary of weight loss injections vs tablets

“There's no single best weight loss treatment. It really comes down to what works for your body, your routine, and where you are on your journey right now.

“If you want the highest average weight loss from the clinical trial evidence, injections like Mounjaro or Wegovy are currently leading the way. If you'd rather avoid needles, a tablet might be a better fit, and new options like Wegovy tablets will make that a more viable choice than ever once they launch in Ireland.

“Think about what matters most to you. Is it convenience? Effectiveness? Price? Needle-free? The good news is that there are more options available than ever before, and a clinician can help you figure out which one will work best for you and your goals.

“If you're ready to get started, you can complete a short consultation with us, and we'll help find a treatment that's safe and suitable for you.”

Ayesha Bashir, weight loss expert at myBMI

Sources

• Tirzepatide Once Weekly for the Treatment of Obesity. (2022). New England Journal of Medicine. [Accessed 20th May 2026].
• Once-Weekly Semaglutide 7.2mg in Adults with Obesity (STEP UP). (2025). PubMed. [Accessed 20th May 2026].
• How Saxenda Works. Saxenda. [Accessed 20th May 2026].
• Oral Semaglutide at a Dose of 25mg in Adults with Overweight or Obesity. (2025). New England Journal of Medicine. [Accessed 20th May 2026].
• Rybelsus Results. Rybelsus. [Accessed 20th May 2026].
• FDA Approves Lilly's Foundayo (Orforglipron), the Only GLP-1 Pill for Weight Loss. (2026). PR Newswire. [Accessed 20th May 2026].
• Mysimba Patient Information Leaflet. EMC. [Accessed 20th May 2026].
• Taking Orlistat: Predicting Weight Loss Over 6 Months. (2011). PMC. [Accessed 20th May 2026].
• Product Update Notifications. Novo Nordisk Australia. [Accessed 20th May 2026].