Wegovy (semaglutide) and Mounjaro (tirzepatide) have been used to manage weight and treat obesity. However, only Wegovy is FDA-approved for weight loss, and that is not the only difference between the two medications.
Both Wegovy and Mounjaro belong to a class of drugs known as GLP-1 agonists, which work by mimicking glucagon-like peptide-1 (GLP-1), a hormone that is in insulin secretion as well as how long food remains in your stomach, therefore having an impact on hunger, digestion and feelings of fullness.
Because of the way this class of drugs affects both insulin and hunger, they have been prescribed both for diabetes management and weight control. However, Wegovy has been clinically studied and approved by the FDA for weight loss, but Mounjaro has not. Let’s take a closer look at some of the differences between Mounjaro and Wegovy.
The main differences between Mounjaro and Wegovy
Wegovy is made by Novo Nordisk. Mounjaro is made by Eli Lilly. They are similar drugs with several significant differences.
Mechanisms of Action
Semaglutide, the active ingredient in Wegovy, belongs to the class of medications known as glucagon-like peptide-1 (GLP-1) receptor agonists. GLP-1 is a hormone that regulates blood sugar levels and appetite.
Semaglutide stimulates GLP-1 receptors in the brain, leading to decreased appetite, increased feelings of fullness, and reduced food intake. Additionally, it slows down stomach emptying, which further contributes to the sense of satiety.
Tirzepatide, the primary component of Mounjaro, is a novel medication that combines the actions of GLP-1 and glucose-dependent insulinotropic peptide (GIP) receptor agonists.
Unlike Wegovy and other GLP-1s, this dual mechanism mimics the action of two hormones and targets specific pathways to regulate blood sugar and appetite.
Prescribed Populations
Wegovy and Mounjaro have both been prescribed for weight loss, but they do have somewhat different purposes and target populations.
Wegovy is approved for individuals with a body mass index (BMI) of 30 or higher or those with a BMI of 27 or higher with at least one weight-related comorbidity such as diabetes, high blood pressure, or high cholesterol.
Mounjaro is only approved for individuals with type 2 diabetes to help manage their blood sugar levels. In such individuals, it can promote weight loss, which can improve symptoms and complications of diabetes.
Effectiveness for Weight Loss
Wegovy has been used by patients with and without diabetes. Adults taking Wegovy have lost about 40 pounds on average, or about 15% of their total body weight.
Weight loss of 5 – 10 pounds a month is not unusual on Wegovy, with some patients showing significantly more weight loss per month, particularly when Wegovy is combined with exercise and calorie reduction.
Mounjaro is usually prescribed to help patients manage type 2 diabetes and is only now being studied for weight loss. Interestingly enough, while it is not yet FDA-approved for weight loss, preliminary studies seem to indicate that it could be somewhat more effective than Wegovy.
In studies of Mounjaro, participants taking the highest 15 mg dose lost 20% of their body weight in about the same time period that patients on Wegovy lost about 15%.
Do not confuse either Wegovy or Mounjaro with simple “appetite suppressants” or other so-called “diet pills.” These are well-researched and effective medications, albeit developed for two distinct purposes. Mounjaro, in particular, has a unique mechanism of action and target audience among the class of GLP-1 agonists since it is the only one that also acts as a (GIP) receptor agonist.
Legality of Use
The greatest difference between Mounjaro and Wegovy is in what they are approved by the FDA to treat. While it is in testing for approval as a weight loss drug, currently, Mounjaro is only approved as a treatment for type 2 diabetes in adults.
Since 2021, Wegovy has approved weight loss in adults and children 12 and older who meet certain criteria. It is not approved nor prescribed as a diabetes treatment.
Weight loss drugs such as Wegov and Mounjaro have been in very high demand. Since Wegovy is one of the only drugs of its kind that has been approved for weight loss, it has become very well-known, and availability is sometimes low, but Novo Nordisk has been ramping up production of the drug to meet the increased demand.
Because of the popularity of Wegovy, it may be easier to get a prescription for Mounjaro. However, it is not for everyone and should be prescribed with discretion for weight loss; speak to your doctor to see if Mounjaro is right for you.
Usage
Wegovy is approved for weight loss in people who are technically obese or overweight with one or more qualifying conditions. Wegovy is not normally prescribed for diabetes control. However, persons who have diabetes can safely take Wegovy. It is commonly prescribed for weight control in people with “prediabetes.”
Mounjaro is a drug prescribed to treat type 2 diabetes by lowering blood sugar. Doctors have been prescribing Mounjaro “off-label” for weight loss. Off-label means that a drug is FDA-approved and generally recognized as safe, but it is being prescribed for a purpose other than that for which it was tested and approved. Doctors are permitted to prescribe approved drugs off-label following their own discretion.
Dosage
Both Mounjaro and Wegovy are given as a subcutaneous (below the skin) injection using a pen-like injector device.
To give this type of injection, you start by sterilizing the injection site with an alcohol swab. Then, pinch a fold of skin at the cleaned injection site to create a small area of tissue.
Remove the cap of the injector pen of either device and carefully insert the needle into the fold of the skin at a 90-degree angle or as directed by your healthcare provider. Push the plunger down to inject the medication.
Either drug can be taken any time of day or night with or without food; the key is that you take your once-weekly injection at the same time each week.
A typical Wegovy dosage schedule for weight loss is:
- First Month: 0.25 mg once weekly (starting dosage)
- Second Month: 0.5 mg once weekly
- Third Month: 1 mg once weekly
- Fourth Month: 1.7 mg once weekly
- Fifth Month: 2.4 mg once weekly (target dosage)
Like Wegovy, Mounjaro is titrated, meaning your doctor will start you out at the lowest possible dose and slowly increase to the maximum effective dosage for weight loss.
Typically, the starting dosage of Mounjaro is 2.5 mg. In addition to the starting dose, Mounjaro is available in 7.5 mg, 10 mg, 12.5 mg, and 15 mg. Similar to Wegovy, your doctor will probably increase your dosage monthly until you build to the maximum dose. In clinical trials, optimal weight loss was seen in patients on the 15mg dose of Mounjaro.
Cost
Both Wegovy and Mounjaro are on the expensive side as prescription drugs go. But of the two, Wegovy is more expensive, with an average price of around $1600 for a one-month supply, whereas Mounjaro is about $1100.
The price you pay for either drug will likely vary depending on whether you have insurance, your particular healthcare plan, and your pharmacy.
Insurance coverage
Insurance coverage for Wegovy or Mounjaro will vary from insurer to insurer. Insurers are often hesitant to provide coverage for drugs that are specifically prescribed for weight loss, such as Wegovy. However, they usually will cover a diabetes management drug like Mounjaro.
Therefore, it could possibly be easier to get insurance coverage for Mounjaro. It is always a good idea to check with your healthcare plan before speaking to your doctor about prescription options for weight loss to see what may or may not be covered.
The makers of both Wegovy and Mounjaro offer patient assistant savings programs for people with commercial or private insurance. Even if your plan does not cover Wegovy or Mounjaro, you may be eligible. Learn more about the Wegovy Savings Offer and the Mounjaro Savings Offer.
Results
Mounjaro and Wegovy work by mimicking the action of certain naturally occurring hormones that are involved in appetite and glucose metabolism.
While the biological impact is similar, Wegovy and Mounjaro act somewhat differently because they mimic the effects of different hormones. Wegovy mimics the action of GLP-1, whereas Mounjaro also acts like GLP-1 in the body. In addition, it mimics the action of another hormone that Wegovy does not, known as GIP.
The actions of both of these naturally occurring hormones and the drugs that mimic them can make you feel fuller quicker and longer, which can curb appetite and help you lose weight.
As mentioned earlier, one of the early clinical trials looking at Mounjaro for weight loss found that it is potentially more effective at its maximum dose than Wegovy, particularly in patients who are both overweight and have type 2 diabetes.
However, Mounjaro is not approved for weight loss, and Wegovy and Mounjaro have never been compared in a head-to-head trial for weight loss. Therefore, it cannot be said with any degree of scientific certainty which medication will provide better results for weight loss in every circumstance.
Side Effects
As to relative side effects, since both drugs work to some degree on digestion, they have very similar side effects that are mostly related to stomach upset and gastric distress. The most common side effects of both drugs are:
- Nausea
- Vomiting
- Gas and bloating
- Indigestion
- Diarrhea
- Constipation
- Abdominal pain
- Upset stomach
Severe side effects such as kidney, liver, or gallbladder issues are rare but have been reported on both medications, so it is important that you tell your doctor if you or anyone in your family has had a history of any such conditions.
Since the most common side effects of Wegovy and Mounjaro are so similar, it’s hard to say which drug may cause you more or fewer issues, and this will likely be based on your particular tolerances or sensitives to the active ingredients in either drug.
