What’s the difference between Mounjaro and Wegovy?

How do Mounjaro and Wegovy work?

Mounjaro and Wegovy are both a type of medication called a glucagon-like peptide 1 (GLP-1) receptor agonist. They work by mimicking a hormone called GLP-1 that occurs naturally in your body to suppress your appetite. This may help you consume fewer calories and lose weight.

GLP-1 works by:

● Sending signals to your brain to tell you you’re full after eating

● Keeping food in your stomach for longer, which helps you feel full

● Regulating your blood sugar levels which may reduce hunger and keep your energy levels stable

What are the differences between Mounjaro and Wegovy?

The main differences between Mounjaro and Wegovy are their active ingredients and the dosage.

Mounjaro and Wegovy both work in the same way to reduce hunger and help you feel fuller for longer, but they contain different active ingredients.

● Wegovy contains the active ingredient semaglutide, a GLP-1 receptor agonist.

● Mounjaro contains the active ingredient tirzepatide. In addition to being a GLP-1 receptor agonist, tirzepatide also mimics another hormone called glucose-dependent insulinotropic peptide (GIP). This dual action may make it slightly more effective for weight loss.

Key differences between Mounjaro and Wegovy

How do I take Mounjaro or Wegovy?

Both Mounjaro and Wegovy come in pre-filled injectable pens that contain the exact dose you need. The dose will vary depending on where you are in your dosing schedule. Each pen contains four doses which will provide you with one dose per week for four weeks. Mounjaro and Wegovy are given as subcutaneous injections (under the skin) in your stomach, thighs, or upper arm.

To use Mounjaro or Wegovy:

● Give your injection on the same day and at the same time each week

● Rotate your injection sites and give your injection in a different place each week to avoid skin irritation and swelling (you can use the same area of your body)

● Give your injection at least two inches away from your belly button

● Avoid injecting into sore, inflamed or broken skin

● Always check your medication and dosage are correct and within the expiry date before giving your injection

● Follow the manufacturer’s instructions and inject your medication

● Dispose of the needle in the sharps bin you have been provided with and store your medication as recommended by the manufacturer

Side effects

Like all medications, Mounjaro and Wegovy can cause side effects in some people. Most side effects are mild and improve within a few weeks, but rarely, side effects can be serious. If your side effects are bothering you, or are getting worse, or not getting better, speak to your clinician.

Black box warnings

Both Wegovy and Mounjaro have an FDA “black box” warning that they have caused thyroid tumours including cancerous tumours in mice and rats. It is not known if these medications can cause thyroid tumours in people. See your clinician immediately if you develop symptoms such as a lump or swelling in your neck, a hoarse voice, difficulty swallowing, or shortness of breath.

Common side effects include:

● Nausea (feeling sick)

● Vomiting (being sick)

● Indigestion

● Abdominal pain

● Diarrhoea

● Constipation

Rare, but serious side effects include:

● Severe allergic reaction (anaphylaxis)

● Inflammation of the pancreas (acute pancreatitis)

● Problems with your kidneys or gallbladder

● Low blood sugar (hypoglycaemia)

Who can’t take Mounjaro or Wegovy?

Mounjaro and Wegovy are not suitable for everyone and may be unsafe for some people. Tell your clinician about any medical conditions or allergies you have before starting your treatment. If you have diabetes, you must talk to your NHS GP before starting weight loss injections as they may interact with other medications you are taking.

You should not use Wegovy if:

● You are allergic to Wegovy or any of its ingredients

● You have an eye condition called diabetic retinopathy

● You have problems with your kidneys

● You are at risk of developing pancreatitis

● You, or anyone in your family have ever had a type of thyroid cancer called medullary thyroid carcinoma (MTC) or if you have an endocrine system condition called Multiple Endocrine Neoplasia (MEN)

You should not use Mounjaro if:

● You are allergic to Mounjaro or any of its ingredients

● You are under 18 years of age

● You are pregnant or breastfeeding

Speak to your doctor before using Mounjaro if:

● You have a condition that affects your stomach emptying, such as gastroparesis

● You have an eye condition such as diabetic retinopathy

● You have a history of pancreatitis

Interactions with other medications

Mounjaro and Wegovy may react with other medications you are taking, changing the way they work or increasing the risk of side effects. Tell your clinician about any other medications, including over-the-counter medicines, herbs or supplements you take regularly before starting your treatment.

Medications that may interact with Mounjaro include:

● Insulin or other diabetes medications such as Metformin: may increase the risk of low blood sugar (hypoglycaemia)

● The contraceptive pill: Mounjaro may affect the absorption of birth control pills, making them less effective

● Some blood pressure medications

● Some thyroid medications

Medications that may interact with Wegovy include:

● Insulin or other diabetes medications

● Some blood pressure medications

● Some anticoagulants (blood thinners)

● Some antibiotics

● Some antidepressants

● Salicylates such as aspirin and some indigestion remedies

Frequently asked questions (FAQs)

Can I switch from Wegovy to Mounjaro?

Yes, it is possible to switch from Wegovy to Mounjaro, or the other way around, but you’ll need to speak to your clinician first. You may decide to switch to a different weight loss medication if you feel your current medication isn’t working as well as you had hoped, or if you are experiencing unpleasant side effects from your current medication.

Is Wegovy or Mounjaro right for me?

Both Wegovy and Mounjaro are safe and effective weight loss treatments that can help you lose weight when combined with a calorie-controlled diet and regular exercise. Which medication is right for you depends on several factors including:

● Your personal preference: you may prefer one treatment over the other

● Your medical history:  either Mounjaro or Wegovy may be more suitable if you have a health condition, or are taking certain medications

● Cost: although the cost of Mounjaro and Wegovy is similar, the price of your medication may be a factor in your decision

● Side effects: you may experience unpleasant side effects while using one of the treatments and choose to try the other instead

If you are unsure whether Mounjaro or Wegovy is the best choice for you, discuss this with your clinician.

What if I miss a dose?

If you miss your dose of Wegovy, and your next dose is more than two days (48 hours) away, take your missed dose as soon as possible. If you miss your dose of Wegovy and your next dose is less than two days (48 hours) away, skip that dose and take your next dose at the usual time.

If you miss your dose of Mounjaro and your next dose is more than four days (96 hours) away, take your missed dose as soon as possible. If more than four days have passed since you missed your dose, skip the missed dose and take your next dose at the usual time.

Can I take Mounjaro if I’m on birth control pills?

As Mounjaro delays stomach emptying, it may make the contraceptive pill less effective which could result in unwanted pregnancy. If you are taking Mounjaro, you should switch to a form of contraception that you don’t take by mouth such as condoms, implants, patches, injections or the IUD.

Which is more effective for weight loss, Wegovy or Mounjaro?

Both Wegovy and Mounjaro are effective medications for weight loss when used correctly. There are currently no studies comparing the effectiveness of Wegovy and Mounjaro, and it’s important to look at all the factors when deciding whether Wegovy or Mounjaro is the best choice for you. In separate studies on Wegovy and Mounjaro:

● Almost 50% of people taking Wegovy had lost 15% or more of their starting weight after 68 weeks on the maintenance dose of 2.4 mg.

● 65% of participants taking Mounjaro at the highest maintenance dose of 15mg lost up to 22.5% of their starting weight after 72 weeks of treatment.

How long can I take Mounjaro or Wegovy to lose weight?

As long as you don’t experience unpleasant or serious side effects, you can keep taking Mounjaro or Wegovy for as long as you need to. Once you reach your desired weight, you can either stop your medication or keep taking it to maintain your weight if your BMI remains high.

Sources

Mounjaro® (tirzepatide) Injection: The First and Only GIP and GLP-1 Receptor Agonist Approved for Type 2 Diabetes Lilly

Mounjaro KwikPen 2.5mg solution for injection in pre-filled pen  emc

Discover the Power of Wegovy (semaglutide) injection Wegovy.com

Wegovy 0.25 mg, FlexTouch solution for injection in pre-filled pen emc

Tirzepatide Once Weekly for the Treatment of Obesity The New England Journal of Medicine

Once-Weekly Semaglutide in Adults with Overweight or Obesity The New England Journal of Medicine