Trulicity vs. Mounjaro: what is the difference?

Trulicity and Mounjaro belong to a class of medications known as GLP-1 receptor agonists. Both drugs treat type 2 diabetes and may be prescribed off-label for weight loss, but they contain different active ingredients and can have slightly different effects. Read on as we explore the differences (and similarities) between Trulicity vs. Mounjaro, and how these medications can support weight loss.

Mounjaro (tirzepatide) is a once-weekly injectable medication that helps people with type 2 diabetes mellitus control their blood sugar levels. The US Food and Drug Administration (FDA) approved the drug to treat type 2 diabetes in May 2022. Eli Lilly, the manufacturer of Mounjaro, is currently seeking FDA approval of Mounjaro for weight loss. Clinical trials are already underway, and the approval may come through sometime in 2023. Until then, health providers may continue prescribing Mounjaro off-label for weight management (more on this in a bit).

Mounjaro differs from Trulicity and other GLP-1 medications because it is a dual GIP/GLP-1 receptor agonist. Unlike Trulicity, which only activates the glucagon-like peptide-1 (GLP-1) receptor, Mounjaro activates both the GLP-1 receptor and the glucose-dependent insulinotropic polypeptide (GIP) receptor. This two-for-one capability seems to make Mounjaro more effective at both weight loss and blood sugar control than single-receptor GLP-1 drugs like Ozempic and Trulicity.

Mounjaro comes in a single-dose prescription pen. Once a week, you inject the medicine just under into the skin of your upper arm, abdomen, or thigh, rotating the injection sites each week. Mounjaro is available in six strengths: 2.5 milligrams (mg), 5 mg, 7.5 mg, 10 mg, 12.5 mg, and 15 mg. The typical starting dosage is 2.5 mg. After four weeks, your health provider may increase your dose to 5 mg. They may continue increasing your dosage as needed every four weeks until you reach the maximum dose of 15 mg, if needed. The goal is to find the smallest dosage of Mounjaro that controls your blood sugar levels. 

In general, Mounjaro is a safe and well-tolerated drug. Side effects tend to be most common when you first start taking Mounjaro, and usually go away with time as your body gets acclimated to the drug. The most common side effects of Mounjaro include:

• Nausea

• Diarrhea

• Decreased appetite

• Vomiting

• Constipation

• Upset stomach or indigestion

• Abdominal pain

Mounjaro may not be safe for people with a personal or family history of medullary thyroid carcinoma or those with Multiple Endocrine Neoplasia syndrome type 2 (MEN 2). Additionally, people with a history of pancreatitis, severe gastrointestinal disease, diabetic retinopathy, kidney or gallbladder problems, or an allergy to the ingredients in Mounjaro may want to use caution when taking Mounjaro. Talk to your healthcare provider about your medical history, current health conditions, and any medications you are taking before starting Mounjaro.

Like Mounjaro, Trulicity (dulaglutide) is an once-weekly injectable medication that helps people with type 2 diabetes control their blood sugar levels. Trulicity received FDA approval nearly a decade before Mounjaro, in 2014. While Mounjaro is only FDA-approved to improve blood glucose levels in people with type 2 diabetes, Trulicity is also FDA-approved to reduce the risk of heart attack, stroke, or death in people who have type 2 diabetes and established heart disease. 

Like Mounjaro, each dose of Trulicity comes in a pre-filled prescription pen, which you inject under the skin of your upper arm, abdomen, or thigh on a weekly basis. The starting dosage for Trulicity is 0.75 mg. After four weeks, your health provider may increase your dosage to 1.5 mg. If needed, they may continue increasing it after each interval of four weeks until the maximum dose of 4.5 mg. Additional strengths of Trulicity include 3 mg and 4.5 mg.

Trulicity is well-tolerated, with mild to moderate side effects that tend to go away as your body gets used to the drug. The most common side effects of Trulicity include:

• Nausea

• Diarrhea

• Vomiting

• Abdominal pain

• Decreased appetite

Trulicity is generally considered safe and effective for most people. But, similar to many prescription medications, some people may be at increased risk of serious side effects when taking Trulicity. Specifically, people with a personal or family history of thyroid cancer, or with a known allergy to any of the ingredients in Trulicity, should not take the drug. Additionally, people with a history of pancreatitis, severe gastrointestinal disease, diabetic retinopathy, or kidney problems should use caution when taking Trulicity.

Given their good safety profile and weight loss effects, some GLP-1 medications are FDA-approved for weight loss, including Wegovy (semaglutide) and Saxenda (liraglutide). Currently, however, neither Trulicity nor Mounjaro are FDA-approved for weight loss, although they may be prescribed off-label for this use. The same goes for Ozempic, which is often prescribed off-label for weight loss. 

Off-label prescribing is quite common, especially in cases where research has found a drug to be helpful for more than its intended condition, as has happened with GLP-1 drugs and weight loss. Off-label prescriptions allow health providers to use their professional judgment in prescribing the best medication for their patients. 

GLP-1 medications like Trulicity and Mounjaro were originally developed to treat type 2 diabetes by improving blood sugar control. These drugs do that by telling your pancreas to release more insulin whenever you’ve eaten sugar or carbohydrates. Trulicity and Mounjaro also inhibit glucagon production, a hormone that raises blood sugar. Lastly, both drugs slow gastric emptying, or the rate at which food leaves your stomach. 

For people with type 2 diabetes, these effects work synergistically to keep their blood glucose levels in check. But, they can also have the effect of lowering your appetite, by making you feel full sooner and longer. As a result, people who take Trulicity and Mounjaro tend to lose weight on the diabetes drug, leading manufacturers to seek FDA approval for obesity and weight loss.

How much weight do people lose on Trulicity vs. Mounjaro? 

People taking 1.5 mg of dulaglutide (Trulicity) lost nearly 7 pounds (3.1kg) in six months, according to one study. Some researchers argue that this amount of weight loss on 1.5mg of dulaglutide is not enough to warrant the drug getting FDA approval for weight loss. But, other research shows higher doses of dulaglutide may be more effective for weight loss. For example, after nine months, those taking 1.5 mg of dulaglutide lost about 7 pounds, on average, compared with the 9 to 10 pounds lost by those taking 3.0 mg and 4.5 mg of dulaglutide, respectively. 

While seven to ten pounds is nothing to sneeze at, it’s helpful to consider the percentage of weight loss as opposed to pure pounds lost. From a percentage perspective, Mounjaro wins, according to a clinical trial that compared the two drugs directly, in a group mostly of men with type 2 diabetes. Tirzepatide (Mounjaro) significantly outperformed dulaglutide (Trulicity) at both blood sugar control and weight loss. After one year, those taking tirzepatide lost around 8% to 14% of their body weight, depending on their dose, compared with less than 1% of body weight lost for those taking dulaglutide. Although, side effects were also more common among those taking tirzepatide than dulaglutide, particularly nausea and constipation. 

Moreover, studies show that Mounjaro can be effective at promoting weight loss in people without diabetes, as well. For example, one large study included 2,500 adults with either a body-mass index (BMI) of 30 or more, or a BMI of 27 or more and a weight-related health condition, but no diabetes. After about a year and four months, those taking tirzepatide (Mounjaro) had lost between 15% to nearly 21% of their body weight (on 5mg and 15mg respectively), with those taking higher doses losing more weight. 

Currently, Mounjaro is not FDA-approved for weight loss. However, the FDA has granted Eli Lilly Fast Track designation to investigate Mounjaro for treating people with obesity, or those with overweight and a weight-related health condition. The clinical trials are expected to be completed by April 2023, which means the drug may be FDA-approved for weight loss as early as this year — especially given the promising results of the first clinical trial. It found that people without diabetes taking 5 mg to 15 mg of Mounjaro lost between 16.5% to 22.4% of their body weight within about a year and four months.

If and when it is approved, Eli Lilly may release the version of tirzepatide for weight loss under a new brand name. Novo Nordisk, another pharmaceutical company, recently went through a similar process with semaglutide, a drug you may know by the name Ozempic. 

Semaglutide is a GLP-1 diabetes medication. It was released in 2017 under the brand name Ozempic to treat type 2 diabetes, but as researchers found it also promoted weight loss, many healthcare professionals began prescribing it off-label for this reason. Eventually, Novo Nordisk received FDA approval for higher doses of semaglutide to treat obesity under the brand name Wegovy. Today, people may use Wegovy or Ozempic for weight loss, although the medications are FDA-approved for different conditions.

Currently, Trulicity is not FDA-approved for weight loss. However, it may be prescribed off-label to people trying to lose weight. In 2020, Trulicity received FDA approval for two higher dosages (3.0 mg and 4.5 mg) to treat type 2 diabetes, as they led to larger improvements in both A1C levels and body weight reduction. Both of these outcomes are beneficial for people with type 2 diabetes, whether or not they also have obesity. In clinical trials, those taking 3.0 mg of Trulicity lost 8.8 pounds, while those taking 4.5 mg lost 10.4 pounds, within nine months. 

Whether you are considering taking Mounjaro, Trulicity, Ozempic or Wegovy for type 2 diabetes or weight loss (or both), these medications are most effective when used in combination with lifestyle changes like diet and exercise. That’s where the Ro Body Program can help. Not only are you connected with a certified healthcare professional who can prescribe the best weight loss medication for you, but you’ll receive personalized guidance on lifestyle changes to support your weight loss.

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Current version

May 15, 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.