Zepbound vs. Mounjaro: what’s the difference?
Key highlights
- Zepbound and Mounjaro have the same active ingredient, tirzepatide, and both drugs are manufactured by Eli Lilly.
- Tirzepatide is a glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist.
- Both drugs are similar in many ways, including their method of administration (subcutaneous injection), side effects, interactions and dosages.
- The main difference between the drugs is that Zepbound is FDA-approved for chronic weight management in adults and Mounjaro is FDA-approved for Type 2 diabetes.
- There are several differences between Mounjaro and Zepbound, including their side effects, insurance coverage, and cost.
- There are several options to save on these medications, including the manufacturer savings card which helps eligible individuals pay as little as $25 per prescription.
Mounjaro (tirzepatide) was initially FDA-approved in 2022 for type 2 diabetes. During clinical trials, researchers found that tirzepatide caused significant weight loss, leading to the approval of Zepbound. Zepbound and Mounjaro are brand names for tirzepatide. Both drugs are made by the same manufacturer, Eli Lilly, and share similar side effects (nausea, diarrhea, vomiting and others).
If both Mounjaro and Zepbound contain the same active ingredient, tirzepatide, does that mean you can use them interchangeably? The answer is not exactly. So, what makes these two medications different?
The main difference between Zepbound vs. Mounjaro is that Zepbound is FDA-approved for chronic weight loss management in adults, and Mounjaro is FDA-approved for type 2 diabetes. Choosing the appropriate brand name option depends on your diagnosed health condition, insurance coverage, and other considerations. Below we will review the differences and similarities between Mounjaro and Zepbound.
What is Zepbound?
Like Mounjaro, Zepbound (tirzepatide) is an insulinotropic receptor (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist prescription medication that is injected once weekly and is intended to be used in combination with a reduced-calorie diet and increased physical activity. Zepbound activates the receptors to secrete hormones to reduce appetite and food intake. The U.S. Food and Drug Administration (FDA) approved Zepbound in 2023. It is manufactured by Eli Lilly. Zepbound is prescribed to people who have a body mass index (BMI) of:
- 30 or greater; or,
- 27 or higher and a weight-related condition such as high cholesterol, type 2 diabetes, high blood pressure, heart disease, or obstructive sleep apnea
Zepbound is a prescription medication that is injected once per week subcutaneously (under the skin) of the stomach, thigh, or upper arm. Zepbound is available in six dosage strengths – 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, and 15 mg. To help manage potential side effects, doctors generally prescribe a starting dosage of 2.5 mg weekly and gradually increase to higher doses every 4 weeks while your body gets used to the medication until an effective maintenance dosage is reached.
What is Mounjaro?
Mounjaro (tirzepatide) is an insulinotropic receptor (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist prescription medication that is used in combination with diet and exercise. It is manufactured by Eli Lilly and was FDA-approved in 2022 for improving blood sugar levels in adults with type 2 diabetes.
Mounjaro is injected once weekly under the skin (subcutaneously) of the stomach, thigh, or upper arm. Mounjaro is available in the same six dosage strengths as Zepbound – 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, and 15 mg. To help manage potential side effects, healthcare providers start at the lowest dosage, 2.5 mg, and gradually increase to higher doses every 4 weeks until blood sugar levels are effectively managed.
What are the differences and similarities between Zepbound and Mounjaro?
Zepbound and Mounjaro have different brand names and approved indications but are similar in many ways. Learn more about why these medications cannot be used interchangeably and what the differences and similarities are:
Active ingredients
Tirzepatide is the active ingredient in Zepbound and Mounjaro. Tirzepatide works by mimicking two naturally produced gut hormones: glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1).
GLP-1 helps slow down digestion by moving food down from your stomach to the intestine more slowly after you eat, which is also known as gastric emptying. Simultaneously, it enhances the release of insulin and inhibits glucagon release which helps with burning body fat. These combined effects help lower blood sugar levels while increasing feelings of fullness which makes you eat less and lose weight with a lower-calorie intake. GLP-1 and GIP also have effects on the brain that influence appetite and satiety.
Mounjaro was the first GLP-1/GIP drug to be approved by the FDA, making it unique among other injectable GLP-1 diabetes medications such as Ozempic (semaglutide) and GLP-1 weight loss drugs such as Wegovy (semaglutide) and Saxenda (liraglutide). The combined ability of GIP and GLP-1 to target both receptors might explain why tirzepatide is more effective in improving blood sugar levels and weight loss.
FDA approval
In May 2022, the FDA approved Mounjaro (tirzepatide) for the treatment of type 2 diabetes for people whose blood sugar levels did not adequately improve with diet and exercise. Mounjaro is intended to be used in combination with a reduced-calorie diet and increased physical activity. While Mounjaro is not FDA-approved for weight loss, it is commonly prescribed off-label for people who are obese or overweight.
Researchers found that Mounjaro was more effective than other GLP-1 medications in controlling blood sugar levels and also found tirzepatide to be effective in producing weight loss, resulting in healthcare professionals prescribing the medication off-label for overweight and obesity.
In November 2023, The U.S. Food and Drug Administration (FDA) approved Zepbound as a treatment for chronic weight management in people with obesity or overweight with at least one weight-related health condition such as high cholesterol, high blood pressure or type 2 diabetes, in combination with diet and exercise.
Side effects
The common side effects of Zepbound and Mounjaro are mild to moderate and gastrointestinal-related. They are similar with some differences.
The most common side effects include:
- Nausea
- Diarrhea
- Vomiting
- Constipation
- Abdominal pain
- Indigestion or upset stomach
- Decreased appetite
Zepbound may have additional side effects including:
- Fatigue
- Injection site reaction (bruising, rash, or irritation at the injection site)
- Hair loss
- Belching
- Heartburn
Other rare but serious side effects of both medications include:
- Severe stomach problems
- Kidney problems (kidney failure)
- Gallbladder problems
- Pancreatitis
- Serious allergic reactions
- Hypoglycemia (low blood sugar)
- Diabetic retinopathy (changes in vision for people with type 2 diabetes)
- Depression
- Suicidal thoughts
Talk to your healthcare provider to determine if Mounjaro or Zepbound is more appropriate for you. Regardless of which medication you are taking, always take the medication as prescribed which helps reduce the unwanted side effects that are common with both medications.
There are certain dietary changes you can consider that may help as well:
- Drink lots of healthy liquids such as water
- Eat foods that are easily digestible such as toast, crackers or rice
- Avoid fried foods, spices, fatty foods and alcohol
- Stop eating once you feel full
- Eat smaller meals more frequently instead of eating larger meals less often
Administration
Zepbound and Mounjaro pens are both self-injected by the patient under the skin (subcutaneously) in the stomach (abdomen), thigh, and upper arm once weekly, at any time of the day with or without a meal. If you like it less visible, inject Zepbound or Mounjaro in the stomach or thigh, instead of the upper arm.
To avoid injection site reactions, rotate the injection site with each dose and do not use the same site for each injection to avoid skin irritation. You should rotate through all three injection sites every three weeks. Do not use the same site for each injection. If you decide to inject in the same area, always use a different spot in that area, at least 1 inch apart.
Zepbound and Mounjaro should be injected under the skin (subcutaneously) and should not be injected intravenously, intramuscularly, or in irritated areas of the skin. If you are also injecting insulin, you can inject Zepbound and Mounjaro in the same area of your body but do not inject them right next to each other or mix the two injections.
Dosage
Mounjaro and Zepbound are available as self-injectable pens in the same six dosage strengths:
- 2.5 mg
- 5 mg
- 7.5 mg
- 10 mg
- 12.5 mg
- 15 mg
Eli Lilly recently released Zepbound vials in dosage strengths 2.5 mg and 5 mg that are self-administered by the patient with a syringe.
The recommended starting dosage of both medications is 2.5 mg injected subcutaneously once weekly. Providers typically increase the dosage in 2.5 mg increments after at least 4 weeks to 5 mg once weekly. The recommended maintenance doses are 5 mg, 10 mg, or 15 mg. The maximum dosage is 15 mg once weekly.
The medication is injected once weekly on the same day each week. If you want to change the day of the week to take your dose, make sure there are at least 72 hours (3 days) between doses. If you miss a dose, take it as soon as possible, within 96 hours (4 days) of your scheduled dosing. If more than 4 days have passed, you should skip the dose and take the next dose on your regularly scheduled day. Do not take 2 doses within 72 hours (3 days) of each other.
Interactions
As with side effects, Zepbound and Mounjaro share similar drug interactions. You should provide your healthcare provider with a full list of medications, vitamins and supplements you are taking to identify any potential interactions.
When taken without any other medications, Zepbound and Mounjaro have a low risk of hypoglycemia. However, this risk increases when combined with other drugs that affect insulin release in the body including insulin, glinines like repaglinide, glipizide (Glucotrol XL), and sulfonylureas. Your provider may lower the dose of these other medications to help prevent hypoglycemia.
Zepbound and Mounjaro should not be taken in combination with other incretin drugs (e.g. GLP-1 receptor agonists or DPP-4 inhibitors). It is not known if the concomitant use of medications acting via similar pathways affects the safety and efficacy of Zepbound and Mounjaro.
Zepbound and Mounjaro may also affect the absorption of oral medications as they slow digestion and make them less effective as a result.
It’s not recommended to drink alcohol while taking Zepbound or Mounjaro as alcohol can worsen gastro-related side effects, increase your risk for hypoglycemia, and hinder weight loss.
Zepbound vs. Mounjaro insurance coverage
Insurance coverage and copays for Zepbound vs. Mounjaro vary based on your insurance plan. Many insurance plans, including Medicare plans, cover Mounjaro for type 2 diabetes but most insurance plans don’t cover weight loss drugs such as Zepbound. Brand-name drugs often have higher copays than generic drugs that have the same approved uses.
To find out if Zepbound or Mounjaro are covered by your plan, review your insurance plan’s drug formulary (list of covered drugs) or contact your health insurance provider for more details about coverage. Many plans have their formulary available online, and you can also request that a copy be sent to you by mail. Some plans may require prior authorization before coverage is approved.
Zepbound insurance coverage
There is variation in the coverage of anti-obesity medications like Zepbound in commercial insurance plans. Check your insurance plan’s formulary to determine if Zepbound is listed. Some plans may require that a prior authorization be submitted when requesting coverage.
If you have commercial insurance that covers Zepbound, you may be eligible to pay as low as $25 for a 1-month or 3-month prescription of Zepbound pen. If your commercial insurance does not cover Zepbound, you may be eligible to pay as low as $650 for a 1-month prescription of Zepbound pen. People who also have government insurance (e.g. Medicare) are generally excluded.
Medicare does not typically cover anti-obesity medications such as Zepbound but some Medicare Advantage and Medigap plans will provide coverage in certain circumstances. Other government, state, and federally-funded healthcare plans may vary in their coverage, including TRICARE, Veterans Affairs, and Medicaid. If you have coverage through Veterans Affairs, you may be able to get Zepbound coverage through the MOVE! Program.
If Zepbound is not currently covered by your insurance plan, or your request for coverage was denied, your healthcare provider can submit an appeal on your behalf.
Mounjaro insurance coverage
Many insurance plans, including Medicare, provide insurance coverage for Mounjaro if prescribed for type 2 diabetes. Check your insurance plan’s formulary to verify if Mounjaro is covered and the copay. If you have insurance coverage through a government-funded program such as Medicare Part D, Medicaid, or Medicare Advantage, Mounjaro may be covered if prescribed for type 2 diabetes. Some insurance plans may require a prior authorization to be submitted prior to authorizing coverage.
If you have commercial insurance that covers Mounjaro, you may be eligible to pay as low as $25 for a 1-month or 3-month prescription of Mounjaro. If your commercial insurance does not cover Zepbound, you may be eligible to pay as low as $473 for a 1-month prescription of Mounjaro. This offer is limited to people prescribed Mounjaro for its FDA-approved indication, type 2 diabetes, without any governmental insurance coverage (e.g. Medicare, Medicaid, etc.).
As Mounjaro is a diabetes medication, it is more likely to be covered by most insurance plans than weight loss medications such as Zepbound, given the exclusions plans like Medicare have for weight loss drugs.
If you are using Mounjaro off-label for weight loss management, and you have not been diagnosed with type 2 diabetes, you will likely have more difficulty obtaining coverage from your insurance plan. Like with Zepbound, you can ask your healthcare professional to submit an appeal or prior authorization on your behalf to your health insurance company to request that they provide coverage.
Availability of Zepbound and Mounjaro
Both drugs have experienced shortages since their release. Although Eli Lilly is increasing manufacturing to meet the exceptional demand for both medications, Reuters has reported that they anticipate shortages to continue throughout 2024.
The FDA Drug Shortages website lists only the initial 2.5 mg dosage of Zepbound and Mounjaro as being available at the time of writing this article. The 5 mg, 7.5 mg, 10 mg, 12.5 mg, and 15 mg dosage strengths are listed as having limited availability which is expected until the end of 2024.
The difference in cost between Zepbound and Mounjaro
The cost of Mounjaro and Zepbound can vary by insurance coverage. Without insurance coverage, there is about a $10 price difference between Zepbound and Mounjaro. When purchasing Mounjaro without insurance, a 4-week supply is listed at approximately $1,069.08. Zepbound cost is slightly less expensive, with an approximate list price of $1,059.87.
The maker of Zepbound, Eli Lilly, recently announced that it will start providing 2.5 mg and 5 mg Zepbound vials directly to patients at lower prices. A 4-week supply of 2.5 mg Zepbound single-dose vial is $399 ($99.75 per vial), and a 4-week supply of 5 mg Zepbound single-dose vial is $549 ($137.25 per vial).
Eli Lilly provides savings cards for both medications to eligible individuals with commercial insurance coverage, potentially lowering the cost. People receiving insurance through federal or state programs such as Medicaid, Medicare, Medigap, DoD, VA, or TRICARE are not eligible for the program.
- People with commercial insurance holders are eligible to participate in the Mounjaro Savings Card program. For those with Mounjaro coverage, the program gives up to $150 in savings per refill; for those without Mounjaro coverage, the savings can reach up to $573 per refill.
- Those who have commercial insurance can participate in the Zepbound Savings Card program. For those with Zepbound coverage, the program offers up to $150 in savings per refill; for those without Zepbound coverage, the savings can reach up to $563 per refill.
Eligibility for Zepbound vs. Mounjaro
Mounjaro is indicated for glycemic control in people with type 2 diabetes. Zepbound is indicated for chronic weight management in individuals who are:
- Obese (BMI of 30 or greater), or;
- Overweight (BMI of 27 or greater) with at least one weight-related condition (such as high blood pressure, type 2 diabetes, obstructive sleep apnea, or high cholesterol)
People with certain medical conditions such as Multiple Endocrine Neoplasia Syndrome type 2 (MEN 2), personal or family history of medulla thyroid cancer, or a known allergy to any of the ingredients in tirzepatide are not eligible to take either medication.
Additionally, some people may be at increased risk of experiencing serious side effects while taking Zepbound or Mounjaro including people who have:
- A history of diabetic retinopathy
- A history of kidney issues or pancreas
- Stomach issues, including problems with digestion or gastroparesis
Individuals who are breastfeeding, pregnant, or planning to become pregnant should not use Mounjaro or Zepbound. If you are using birth control pills, your healthcare provider may recommend another form of contraceptive because both medications slow digestion and may reduce the absorption and effectiveness of oral medications including oral contraceptives.
You should always inform your healthcare provider about all of your personal and family medical history, as well as any prescription drugs or over-the-counter supplements you are taking before starting Mounjaro or Zepbound. Both medications are indicated only for adults 18 years of age and older.
Which medication works better, Zepbound or Mounjaro?
Mounjaro and Zepbound work effectively for people with type 2 diabetes, obesity or overweight, or both. In clinical trials that study people with obesity and without diabetes, Zepbound led to an average of 15%-21% loss of body weight after 18 months. Participants also experienced significant cardiometabolic health improvements in other aspects such as reduced waist circumference, lower cholesterol, lower blood pressure, and improved physical functioning.
Over 95% of people with prediabetes at the start of the trial had normal blood sugar levels by the end of the trial.
Hemoglobin A1c (HbA1c) levels were reduced by an average of 1.87%-2.07% in a clinical trial involving individuals with type 2 diabetes. 80% of those taking 15 mg of Mounjaro achieved target levels of 6.5% or less, and up to 52% of participants achieved a level below 5.7%. Collectively, people lost 15–21 lbs after 40 weeks of taking Mounjaro, with the higher dosages resulting in greater weight loss.
Is Zepbound or Mounjaro right for me?
It depends on your health condition. Insurance companies typically provide coverage for medications prescribed for their FDA-approved indication so your insurance coverage may be a primary consideration when selecting which medication is right for you. Mounjaro is indicated for type 2 diabetes, while Zepbound is indicated for chronic weight management in people with obesity or overweight with at least 1 weight-related health condition. Both medications are considered to be safe and effective treatment options. Speak with your healthcare provider to determine which medication is most suited for your health condition, treatment goals, and insurance coverage options.
Your tolerance for potential side effects may be another consideration. Zepbound has slightly more potential side effects according to its prescribing information, including belching, dizziness, hair loss, and more serious potential side effects such as suicidal thoughts. Although these side effects are rare, you should discuss the risks and benefits with your healthcare provider.
Lastly, the availability of both medications may be another factor due to drug shortages. Speak with your pharmacy to confirm the availability of both medications and consider alternative medications.
Can I switch from Mounjaro to Zepbound?
If you are currently taking Mounjaro for weight loss, the decision to switch to Zepbound is usually based on availability, insurance coverage, and cost, as both medications have the same active ingredient.
Speak to your healthcare provider about switching from Mounjaro to Zepbound. As both medications have the same active ingredient, you should be able to stay on the same dosage and your body should react to both medications the same way. Both Zepbound and Mounjaro are available in the same dosage strengths.
How to save money on Zepbound and Mounjaro
Eli Lilly provides a Mounjaro Savings Card and Zepbound Savings Card to eligible patients with commercial insurance for as low as $25 for a 1-month or 3-month prescription.
If you are not eligible for the savings card, you can consider purchasing compounded tirzepatide which has the same active ingredient as Zepbound and Mounjaro.
Bottom line
Zepbound and Mounjaro are two brand names manufactured by Eli Lilly, with the same active ingredient, tirzepatide. These GLP-1/GIP once-weekly injections share many similarities such as their side effects, dosage strengths, and interactions. The main difference is that Zepbound is FDA-approved for weight loss and Mounjaro is FDA-approved for type 2 diabetes. There may be differences in insurance coverage for these medications which varies by insurance plan.
