Tirzepatide versus Semaglutide for weight loss

Similarities between tirzepatide and semaglutide

Tirzepatide and semaglutide are approved weight loss treatments that work by targeting the receptors of specific hormones that are released when you eat, specifically glucagon-like peptide-1 (GLP-1).

GLP-1 works by signalling to your body to create more insulin to manage rising blood glucose levels. It also signals to your brain that you are full, so you stop eating.

Tirzepatide is also a glucose-dependent insulinotropic polypeptide (GIP) and GLP-1 receptor agonist, mimicking the actions of both GLP-1 and GIP. Like GLP-1, GIP also increases feelings of fullness, reduces hunger, and regulates blood sugar levels.

When injected as Mounjaro or Wegovy, tirzepatide and semaglutide are once-weekly self-injectable medications. This means you’ll need to inject your chosen medication on the same day each week, at around the same time. Semaglutide is also available in the form of a Wegovy tablet.

Both tirzepatide and semaglutide can be injected into your:

• abdomen
• upper thigh
• upper arm

Semaglutide is also available in the form of an oral pill.

Despite both tirzepatide and semaglutide belonging to a class of medications called GLP-1 receptor agonists, there are some subtle but distinct differences between them.

Tirzepatide

Tirzepatide is the active ingredient in the weight loss injection called Mounjaro. It is a newer dual-acting medication that acts on GLP-1 and GIP receptors in the body, mimicking the natural GLP-1 and GIP hormones.

Mounjaro (tirzepatide) is manufactured by Eli Lily.

Semaglutide

Semaglutide is the active ingredient in Wegovy, a licensed weight loss injection, it is also available and licensed in the form of an oral pill. It contains the same active ingredient as Ozempic, a type 2 diabetes treatment. Although it may be possible to get Ozempic off-label for weight loss, this has led to a shortage of medication for those who need it to treat diabetes. At Asda Online Doctor, we don’t prescribe Ozempic for weight loss, instead we prescribe Wegovy which contains the same active ingredient at higher dosages that can enhance weight loss, we also prescribe the Wegovy pill.

Semaglutide is a GLP-1 receptor agonist that mimics the GLP-1 hormone and works by:

• regulating appetite
• increasing feelings of fullness
• reducing hunger and food cravings
• slowing down the transit of food through the stomach
• lowering blood sugar

The semaglutide pill and injection work slightly differently due to the way they are taken, but they have the same effect. For example, they both work in the same way to increase feelings of fullness and lower your appetite. Here is an at-a-glance overview on the difference between semaglutide pill and injection:

Find out more information on the Wegovy pill here.

Wegovy (semaglutide) is made by Novo Nordisk.

Here is a comparison table summarising the similarities and differences between tirzepatide and semaglutide injectable pens. Please note that the best weight loss treatment for you also depends on your health conditions and current medications.

Tirzepatide and semaglutide are prescription-only medications which means you must have a prescription from a doctor in order to obtain them. You’ll also need to meet some specific criteria to obtain Mounjaro or Wegovy from online services like Asda Online Doctor. For example, you will need to be at least 18 years old and have a body mass index (BMI):

• over 30, or
• at least 27 with at least 1 weight-related condition like high blood pressure

If you feel Wegovy (semaglutide) or Mounjaro (tirzepatide) injections may be effective weight loss treatments for you, start a weight loss consultation with one of our doctors.

If you are considering semaglutide in the form of the oral pill but are unsure which may be better for you out of the pill and the injection, take a look at our comparative overview:

*data comes from the OASIS 4 trial of Wegovy tablets

**data taken from the emc’s Summary of Product Characteristics for Wegovy

Both tirzepatide and semaglutide are GLP-1 receptor agonists and mimic the actions of GLP-1. They affect the area of the brain which controls hunger and delays the time it takes for food to travel through your stomach. So, they work by making you feel full for longer periods of time after eating, which results in a lower calorie intake and weight loss.

Tirzepatide also mimics the action of another hormone, GIP. Although it is not fully understood what GIP does, it is believed to enhance the effects of GLP-1, resulting in greater weight loss.

Tirzepatide and semaglutide are both effective for weight loss. Clinical trials have shown that tirzepatide can help people lose an average 22.5% of their starting body weight after 72 weeks, when they use the highest maintenance dose of 15mg.

At the highest maintenance dose of 7.2mg per week, semaglutide injection can help people lose an average 21% of their starting body weight after 72 weeks. On the semaglutide pill, people lose an average of up to 17% of their starting weight after 64 weeks.

Because tirzepatide and semaglutide work differently, the doses available for each weight loss medication are different.

Wegovy (semaglutide) injection dosages

• Starting dose (weeks 1 to 4) – 0.25mg per week
• Weeks 5 to 8 – 0.5mg per week
• Weeks 9 to 12 – 1mg per week
• Weeks 13 to 16 – 1.7mg per week
• Maintenance dose (weeks 17 to 20) – 2.4mg per week
• Maintenance dose (weeks 21+) – 7.2mg per week

Wegovy (semaglutide) pill dosages

• Starting dose (Month 1) – 1.5mg per week
• Month 2– 4mg per week
• Month 3– 9mg per week
• Maintenance dose (Month 4 onwards) – 25mg per week

Mounjaro (tirzepatide) dosages

• Starting dose (weeks 1 to 4) – 2.5mg per week
• Weeks 5 to 8 – 5mg per week
• Weeks 9 to 12 – 7.5mg per week
• Weeks 13 to 16 – 10mg per week
• Weeks 17 to 20 – 12.5mg per week
• Weeks 21+ – 15mg per week

Semaglutide and tirzepatide are injected once weekly with each injection dose titrating up every 4 weeks until you reach either your preferred or the maximum weekly maintenance dose.

Semaglutide pill is taken once daily on an empty stomach, with each pill dose titrating up every month until you reach the maintenance dose of 25mg.

The side effects of tirzepatide and semaglutide injectionsare similar.

Common side effects of tirzepatide and semaglutide include:

• feeling sick (nausea)
• being sick (vomiting)
• constipation
• diarrhoea
• stomach pain
• fatigue
• low blood sugar (hypoglycaemia)

Less common side effects of semaglutide and tirzepatide include:

• fast heartbeat
• raised pancreatic enzymes
• delayed stomach emptying
• increased bilirubin levels

Some serious side effects of tirzepatide and semaglutide include:

• inflamed pancreas
• severe allergic reactions (difficulty breathing or swallowing, swollen lips, tongue or throat, and a rapid heartbeat)

Side effects of the Wegovy pill

You may experience a higher chance of stomach-related side effects on the Wegovy pill since the medication is absorbed in the digestive system and taken on an empty stomach.

Common side effects of Wegovy tablets include:

• feeling sick (nausea)
• diarrhoea
• being sick (vomiting)
• constipation
• low blood sugar in people with type 2 diabetes
• gas
• stomach ache or pain
• heartburn
• belching or bloating
• dizziness
• tiredness
• headache
• changes to taste
• altered skin sensation
• hair loss

Wegovy pills can also cause some serious side effects. Speak to your doctor straight away or call 999 in an emergency if you experience any of the following:

• inflammation of the pancreas
• gallbladder problems
• low blood sugar
• dehydration
• severe stomach problems
• serious allergic reactions
• changes in vision, especially in people with type 2 diabetes

For more specific information on the Wegovy pill and its side effects, check out our dedicated page.

You can find here our at-a-glance overview of the prices of semaglutide (injection and pill) and tirzepatide.

If you’re looking to get weight loss medication on the NHS, currently Wegovy injections (semaglutide), liraglutide (formerly Saxenda, now Nevolat), and Mounjaro (tirzepatide) are available. Your GP will need to refer you to a specialist weight management service for you to obtain a prescription in most cases, though people with the ‘highest clinical need’ can now be prescribed Mounjaro from some GPs.

➤ You can find out more about what this means and other prescribing requirements for getting weight loss injections on the NHS in our guide.

If you are considering weight loss injections, choosing between tirzepatide and semaglutide will depend on several factors, including:

• individual needs
• medical history
• your overall weight loss goals

Both medications offer benefits, but their differences in how they work, their effectiveness, and the potential risk of side effects can mean that one may be more suitable for you than the other. Here, we explore who might benefit most from tirzepatide or semaglutide.

1.Type 2 diabetes patients

In the UK the weight loss injection Mounjaro (which contains tirzepatide) is also approved for the management of type 2 diabetes. That means Mounjaro may be more advantageous for people looking to control their weight and blood sugar levels.

The combined action on GLP-1 and GIP receptors stimulates insulin secretion from the pancreas, helping to manage blood sugar levels. Semaglutide, on the other hand, also stimulates the production of insulin but only through its action of mimicking GLP-1. Therefore, Mounjaro may have more enhanced effects because it is both a GLP-1 and GIP receptor agonist.

2. Enhanced weight loss

Both tirzepatide and semaglutide are effective weight loss medications. However, tirzepatide may lead to an increased weight reduction compared to semaglutide. At the maximum maintenance doses, the following has been demonstrated:

• tirzepatide results in an average weight loss of 22.5% over 72 weeks
• semaglutide injections causes an average weight loss of 21% over 72 weeks
• semaglutide pills result in an average of up to 17% weight loss in 64 weeks

The increased potential weight loss using tirzepatide could be appealing for people looking to lose a significant amount of weight. However, it is important to consider the risk of side effects which are possible with both types of weight loss medication.

3. Sensitivity to side effects

Tirzepatide and semaglutide share similar side effects, including feeling or being sick, and general gastrointestinal discomfort. The Semaglutide pill may cause slightly different effects because it is administered differently. However, everyone responds differently to the medication, so there is no way of knowing if either medication will cause more or less side effects than the other.

4.Cost considerations

Tirzepatide and semaglutide are not cheap medications when it comes to weight loss. It is important to review the cost of both tirzepatide and semaglutide before committing to treatment.

Wegovy (semaglutide) injections are cheaper than Mounjaro (tirzepatide) at the lower doses when you request weight loss injections from Asda Online Doctor. However, the maintenance doses of Wegovy are more expensive than the Mounjaro maintenance doses. So, if cost is a deciding factor, Mounjaro may be more suitable for you in the long term.

5. Worrying about self-injecting

If you are finding that you are currently undergoing weight loss treatment with injections and would prefer to switch to an alternative with a similar effect but different method of taking it, the semaglutide pill may be a suitable option for you.

Choosing between tirzepatide and semaglutide for weight loss depends on several factors, particularly your health needs and weight loss goals.

At Asda Online Doctor we offer both medications under the brand names Mounjaro (tirzepatide) and Wegovy (semaglutide). While tirzepatide mimics the actions of 2 hormones and offers greater weight loss potential, semaglutide also has a reliable safety profile and requires less time to reach its highest maintenance dose for most patients, it is also available in the form of a pill so if you’re unsure about self-injecting it may be a suitable alternative.

Understanding the differences between weight loss treatments can help you make a choice that’s tailored to your situation, ensuring a beneficial, successful, and sustainable weight loss journey.