Mounjaro vs. Wegovy: what is the difference?

Weight loss medications are showing up all over the news and social media. Wegovy and Ozempic are the most well-known of these medications, but they’re also currently experiencing a drug shortage for certain doses. Enter: Mounjaro, another injectable type 2 diabetes medication that can lead to weight loss. 

If you’re interested in losing weight, you probably want to know more about how these drugs work, and what you can expect when it comes to results, side effects, and cost. Read on as we break down the differences between Mounjaro and Wegovy.

Wegovy (semaglutide) and Mounjaro (tirzepatide) are both prescription injectable medications approved by the U.S. Food and Drug Administration (FDA), intended to be used in combination with lifestyle changes like diet and exercise. Wegovy is approved and prescribed for chronic weight management to people who have obesity (BMI of 30 or higher) or who are overweight (BMI of 27 or higher) and have a weight-related health condition, such as type 2 diabetes, high blood pressure, or high cholesterol. 

Mounjaro, on the other hand, is approved to treat type 2 diabetes by improving blood sugar control. However, because Mounjaro often leads to significant weight loss, health providers may prescribe it off-label for this purpose. Off-label prescriptions allow health providers to use their discretion in prescribing the best medication for their patients. The FDA is currently reviewing tirzepatide, the active ingredient in Mounjaro, as a medication for weight loss, and it may be approved for weight loss in the near future. Until then, health providers can continue to prescribe it off-label. 

Both Wegovy and Mounjaro work by mimicking glucagon-like peptide-1 (GLP-1), an incretin hormone involved in insulin secretion, gastric emptying (the rate at which food moves through your stomach), and appetite. Normally, your body activates these receptors immediately after you eat for a short period. But with Wegovy and Mounjaro, these receptors stay activated for up to a week, helping to keep blood sugar levels steady, slowing down digestion, and reducing your appetite.

Additionally, Mounjaro targets another receptor in the brain known as glucose-dependent insulinotropic polypeptide (GIP). This makes Mounjaro unique among GLP-1 medications like Ozempic and Wegovy, because it mimics two hormones at once, as opposed to one. As we’ll explore in the next section, this may make it more effective at appetite control and weight loss. 

Mounjaro and Wegovy can lead to weight loss, but Mounjaro has been shown to be more effective at supporting weight loss and lowering blood sugar. In one study, people taking Wegovy lost nearly 15% of their body weight, on average, within a year and a half. In studies of Mounjaro, participants taking the highest 15 mg dose lost 20% of their body weight in about the same time period. 

Studies comparing the two medications directly have likewise confirmed that the highest dose of Mounjaro produces more weight loss than Wegovy. (Mounjaro also lowered blood sugar levels to a larger extent than Wegovy, which may be a consideration for people with type 2 diabetes.) 

Mounjaro is dose-dependent when it comes to weight loss. That means that people who take higher doses tend to lose more weight. For example, people with obesity taking the highest 15 mg dose of Mounjaro lose nearly 21% of their body weight, as we mentioned above. Those taking 10 mg weekly lose 19.5% of their body weight, while those taking 5 mg weekly lose 15%, in the same time period. 

Mounjaro is available in different dosage strengths: 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg and 15 mg. The starting dosage of Mounjaro is 2.5 mg, taken weekly. When you first start Mounjaro, health providers will slowly increase your dosage over a period of weeks, and continue to do so until your blood sugar is adequately controlled. Wegovy follows a similar titration schedule when you first start treatment, with lower dosage strengths in the beginning. But, eventually, the goal is for you to reach the maintenance dosage for Wegovy of 2.4 mg weekly.

Wegovy was FDA-approved for weight loss in 2017. However, Mounjaro is currently only approved to treat type 2 diabetes. 

But, in 2022, Eli Lilly, the manufacturer of Mounjaro, announced that the FDA granted Fast Track designation for tirzepatide — the active ingredient in Mounjaro — to be investigated as a treatment for obesity and overweight. The Fast Track designation is designed to accelerate the process for drugs to be developed, tested, and approved. If all goes well, Mounjaro could be approved for weight loss as soon as late 2023.

Until then, health providers may prescribe Mounjaro off-label to their patients.

Mounjaro and Wegovy have different active ingredients — tirzepatide and semaglutide, respectively — but the medications cause similar side effects. Given how the drugs impact on the stomach and intestines, their side effects are typically gastrointestinal and may include:

• Nausea

• Diarrhea

• Vomiting

• Constipation

• Abdominal pain

• Upset stomach or indigestion

Other common side effects for both Mounjaro and Wegovy may include belching, flatulence, bloating, and gastroesophageal reflux disease. Additionally, people taking Wegovy may also notice headache, fatigue, dizziness, gastroenteritis, and runny nose or sore throat.

Nausea and diarrhea are the most common side effects for Wegovy and Mounjaro. Up to one-third of people taking Mounjaro experience nausea, and almost a quarter experience diarrhea. Nearly half (44%) of people taking 2.4 mg weekly Wegovy experience nausea, and around one-third experience diarrhea. Here’s the good news: these side effects are manageable for most people, and they usually go away with time as your body gets used to the medication. 

In rare cases, more serious side effects can occur. For example, people who have type 2 diabetes may be more likely to experience diabetic retinopathy when taking Wegovy or Mounjaro. If you notice any changes to your vision, like floaters or blurriness, talk to your healthcare provider immediately. If you are taking insulin or insulin secretagogues, you may be more likely to experience hypoglycemia. In these cases, your healthcare provider may adjust your dosage of insulin to avoid your blood sugar from dropping too low. 

Acute pancreatitis, kidney or gallbladder issues may also occur, which is why people with a history of these are not recommended to use Mounjaro or Wegovy.

Lastly, rare but serious side effects unique to each drug include severe gastrointestinal disease for Mounjaro, and increased heart rate, and suicidal behavior or ideation for Wegovy.

Wegovy is more expensive than Mounjaro. Without insurance, Wegovy costs $1,349.02 for a four-week supply, while Mounjaro costs $1,023.04. Neither medication has a generic version at this time.

The price you pay for Wegovy and Mounjaro can vary depending on your insurance plan and the pharmacy you use. Both drug makers offer 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.

Cost is only one consideration when starting a new treatment plan, but it is a major one. Before you decide between Mounjaro and Wegovy, consider calling your insurance provider to check if they cover either drug and learn more about the co-pays you can expect. If the drug isn’t covered, ask your health provider to request insurance authorization on your behalf (if you’re part of the Ro Body Program, our insurance concierge can help you with this). 

For additional savings on Mounjaro or Wegovy, call local pharmacies to find the best price. Ask if they are offering any coupons for Mounjaro or Wegovy. Sometimes, ordering a 3-month supply is more affordable than a 1-month supply. Online pharmacies may have more competitive pricing, and offer the convenience of home delivery — often with free shipping.

No. GLP-1 medications like Wegovy and Mounjaro should not be used together. They also should not be used with other GLP-1 medications, or medications that contain the same active ingredient as Mounjaro or Wegovy. Also, it is not currently known if it is safe — or even effective — to use these medications simultaneously as other weight loss medications, either.

Whenever you start a new medication, it’s a good idea to tell your healthcare provider about any other medications or supplements you are taking, to avoid any drug interactions. With drugs like Mounjaro and Wegovy, this is especially important as both drugs delay gastric emptying, which can impact your body’s absorption of any oral medications you are taking. One example is contraceptive pills: while the drug label of Wegovy doesn’t mention anything about interactions with contraception methods on their drug label, the manufacturers of Mounjaro specifically mention that the absorption of oral contraceptives may be affected. The drug maker says that those using oral contraceptives should switch to a non-oral contraceptive method, like a patch or an IUD.  

Mounjaro and Wegovy have similar contraindications. You shouldn’t take either medication if you develop or have a history of any of the following:

• Pancreatitis

• Acute kidney injury

• Acute gallbladder disease

• Medullary thyroid carcinoma

• Multiple endocrine neoplasia syndrome type 2

• Allergy to any of the active or inactive ingredients in the medication

Additionally, people who have severe gastrointestinal disease should not take Mounjaro. You should not take Mounjaro or Wegovy if you are pregnant or planning to get pregnant. Given the long half-life of the drug, your health provider may recommend you stop using Wegovy at least two months before you plan to get pregnant.

If you are taking other medications for other health conditions, your health provider may recommend extra monitoring or adjusting your dosage to avoid additional side effects. For example, because Mounjaro and Wegovy both lower blood sugar, people who take insulin or insulin secretagogues may need to lower their dosage of insulin. Both medications can also lower blood pressure, so people taking medications for high blood pressure may need to be more cautious.

Currently, Wegovy is experiencing a shortage that is expected to last through the end of summer 2023. For that reason alone, you may be interested in switching to Mounjaro. However, you might consider switching from Wegovy to Mounjaro for several other reasons, or vice versa.

• Side effects: Both drugs cause similar side effects, but you may find the side effects of one drug more tolerable than the other. If you feel the side effects are becoming too much, talk to your healthcare provider about switching to an alternative.

• Cost: Both drugs are expensive, but Mounjaro is more affordable than Wegovy. However, the ultimate cost of either drug can depend on your insurance plan. If your plan covers one but not the other, it may be worth making the switch.

• Effectiveness: Studies show that Mounjaro leads to more weight loss than Wegovy. Of course, every individual is different, and your body may respond better to one drug over the other. If you are taking Wegovy or Mounjaro and don’t feel like you are losing weight the way you expected, you might want to switch to a different medication.

If you are taking Wegovy or Mounjaro and think you’d like to switch to another medication, talk to your healthcare provider before you stop taking your medication. They can help you decide on the most appropriate drug for you, and also provide a schedule for safely switching from one drug to the other to minimize side effects.

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Current version

June 29, 2023

Written by

Amelia Willson

Fact checked by

Felix Gussone, MD

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About the medical reviewer

Felix Gussone, MD, Ro

Felix Gussone is a physician, health journalist and a Manager, Medical Content & Education at Ro.