Wegovy vs. Mounjaro side effects

In this article:

• What’s the difference between Wegovy and Mounjaro?
• What are the side effects of Wegovy?
• What are the side effects of Mounjaro?
• Wegovy vs. Mounjaro side effects comparison
• Is Mounjaro better than Wegovy?

In this article

• What’s the difference between Wegovy and Mounjaro?
• What are the side effects of Wegovy?
• What are the side effects of Mounjaro?
• Wegovy vs. Mounjaro side effects comparison
• Is Mounjaro better than Wegovy?

Wegovy (semaglutide) and Mounjaro (tirzepatide) are both prescription drugs that help regulate blood sugar and decrease appetite. However, the Food and Drug Administration (FDA) has approved them for different purposes: Wegovy is approved as a weight loss medication, and Mounjaro is approved as a Type 2 diabetes treatment. Mounjaro’s active ingredient, tirzepatide, is sold as an FDA-approved weight loss drug under the name Zepbound.

With such similar drugs on the market, many people may wonder which is better and which is less likely to cause common side effects. Here’s what the experts say.

What’s the difference between Wegovy and Mounjaro?

Wegovy (semaglutide) and Mounjaro (tirzepatide) are two brand-name injection drugs that have similar effects on the body, but they’re not the same medication. For starters, they don’t have the same active ingredient and are in different drug classes.

“Semaglutide and tirzepatide are both hormonal analogs that affect receptors in the body that induce satiety and slow gastric emptying,” explains Mir Ali, MD, board-certified general surgeon, bariatric surgeon, and medical director of MemorialCare Surgical Weight Loss Center at Orange Coast Medical Center in Fountain Valley, California. “The difference is that semaglutide affects one receptor, GLP-1, whereas tirzepatide affects the GLP-1 receptor and the GIP receptor.” In other words, Wegovy is solely a glucagon-like peptide-1 (GLP-1) receptor agonist, while Mounjaro is a dual GLP-1 and GIP receptor agonist.

Aside from having different active ingredients and drug classes, these medications have different FDA-approved indications, dosages, and side effect frequencies:

• FDA-indicated uses: Wegovy is approved for chronic weight management in adults and children 12 years and older with obesity. Mounjaro is approved as an adjunct therapy to diet and exercise for adults with Type 2 diabetes. It is sometimes prescribed off-label for weight loss.
• Dosage: Wegovy’s dosage is lower than Mounjaro’s dosage. Wegovy starts at 0.25 milligrams (mg) per week and maxes out at 2.4 mg weekly. Mounjaro starts at 2.5 mg and maxes out at 15 mg per week.
• Forms: Wegovy is only available in single-dose injection pens, whereas Mounjaro is available in injection pens and as single-dose vials.
• Side effect frequencies: The two drugs have very similar lists of common side effects, but Wegovy causes side effects more often. However, it’s important to remember that side effect profiles and severity vary from person to person, according to Michelle Lin, DO, family medicine provider and owner of My Family Doc in Las Vegas, Nevada.

RELATED: Can I start Wegovy at 1.7 mg?

What are the side effects of Wegovy?

Clinical trials of Wegovy showed that it frequently causes gastrointestinal side effects. About 44% of adults reported nausea on Wegovy (compared to 16% of participants on a placebo). After nausea, the most frequent adverse reactions included diarrhea (30%), constipation (24%), and vomiting (24%).

Other common Wegovy side effects include:

• Abdominal pain or indigestion
• Headache
• Fatigue
• Dizziness
• Sore throat and runny nose

Like most medications, Wegovy use also comes with a risk of serious side effects. Uncommon but severe side effects may include:

• Stomach paralysis (gastroparesis)
• Pancreatitis (inflamed pancreas)
• Acute kidney or gallbladder problems
• Low blood sugar (hypoglycemia), especially for people with diabetes
• Retinal disorders and changes in vision
• Increased risk of thyroid cancer
• Serious allergic reaction

It’s essential to seek immediate medical advice from a healthcare provider if you experience any serious symptoms after starting Wegovy. You might need to stop using Wegovy or switch to a lower dose. “Many times, the dangerous and more notable side effects … are due to abuse of these medications,” Dr. Lin says. 

What are the side effects of Mounjaro?

Mounjaro’s side effect profile is similar to Wegovy’s, although fewer clinical trial participants experienced unpleasant symptoms. About 12% of participants experienced nausea and/or diarrhea. The next most common side effects were indigestion (8%), constipation (6%), and stomach pain (6%). When gastrointestinal side effects did occur, the complaint typically followed a dosage increase. 

Other potential side effects of Mounjaro include: 

• Decreased appetite
• Burping
• Gastroesophageal reflux disease (GERD)
• Heart rate increase (tachycardia)
• Injection site reactions

Like Wegovy, Mounjaro may cause serious side effects, such as:

• Severe stomach problems such as gastroparesis 
• Pancreatitis (inflamed pancreas)
• Acute kidney or gallbladder problems
• Hypoglycemia 
• Increased risk of thyroid cancer 
• Changes in vision
• Serious allergic reactions 

Tell your prescriber right away if you develop serious side effects after starting Mounjaro. Seek urgent medical attention if you experience signs of an allergic reaction to Mounjaro.

Wegovy vs. Mounjaro side effects comparison
	Wegovy		Mounjaro
Side effect	Applicable?	Frequency	Applicable?	Frequency
Nausea	Yes	44%	Yes	12%
Vomiting	Yes	24%	Yes	5%
Constipation	Yes	24%	Yes	6%
Diarrhea	Yes	30%	Yes	12%
Indigestion	Yes	9%	Yes	8%
Stomach pain	Yes	20%	Yes	6%
Headache	Yes	14%	No	–
Sore throat and runny nose	Yes	12%	No	–
Dizziness	Yes	8%	No	–

Frequency is not based on data from a head-to-head trial. This may not be a complete list of adverse effects that can occur. Please consult with your healthcare provider to learn more.

Sources: DailyMed (Wegovy, Mounjaro)

Is Mounjaro better than Wegovy?

There is no one-size-fits-all answer to whether Mounjaro is better than Wegovy. Both are effective drugs for their approved uses. That said, Mounjaro has a lower incidence rate of side effects than Wegovy. Some research also suggests that Mounjaro may more effectively control blood sugar levels and induce weight loss than Wegovy.

Only 12% of clinical trial participants experience nausea on Mounjaro compared to 44% on Wegovy. Why the difference? Healthcare providers still aren’t sure. “Since [tirzepatide] affects two receptors, it may be that stimulating both receptors decreases nausea, though this is speculation,” Dr. Ali says.

RELATED: Wegovy vs. Mounjaro dosage chart: How to switch medications

A study from 2021 comparing tirzepatide and semaglutide found that tirzepatide lowered blood glucose levels by up to 2.3% while also inducing significantly more weight loss than semaglutide. In a more recent study funded by Lilly, participants with obesity but without diabetes lost more body weight after 72 weeks of treatment with tirzepatide (the active ingredient in Mounjaro and Zepbound) than they did with semaglutide (the active ingredient in Wegovy and Ozempic) when taking the maximum dose. Those taking tirzepatide lost an average of 20.2% of their initial body weight, while those who took semaglutide lost 13.7% of their initial body weight.

Of course, even though Mounjaro might present a lower risk of side effects and be slightly more effective, that doesn’t make it the best drug for everyone. Both of these medications are considered safe and effective for their approved uses. Only a healthcare professional with knowledge of your medical history, health condition(s), and other prescription medications can determine whether Mounjaro or Wegovy is better for you—or whether you should consider similar medications like Ozempic or Zepbound.