What you’ll learn:
- Both Mounjaro® and metformin can be prescribed for off-label weight loss, but Mounjaro® will likely be more effective.
- Metformin is more affordable, often costing under $20 per month, while Mounjaro® can exceed $1,000 without insurance.
- Metformin is taken as a pill up to twice daily, while Mounjaro® is a once-weekly self-administered injection.
The landscape of weight loss medications has undergone significant changes in recent years. GLP-1 receptor agonists, like Ozempic®, have changed the way people approach weight loss. While initially designed for type 2 diabetes management, Ozempic® has become a potential solution for off-label weight loss. But it isn’t the only one. Mounjaro® and metformin are two other diabetes medications that have become more popular for off-label weight loss use.
Could one of these be right for you? There’s a lot to consider when choosing a medication for weight loss. While you will ultimately coordinate with a healthcare provider (or Noom Med) to prescribe these medications, if needed, it’s good to know the similarities and differences between them first. You’ll also have to think about costs, insurance coverage, effectiveness, and how you take them before you commit to a program.
Both medications offer unique benefits, but the best choice depends on your health goals, medical history, and lifestyle. Understanding how metformin compares to Mounjaro® can help you make an informed decision about which might be the right fit for you. Let’s take a closer look at how they work, their effectiveness, side effects, and more.
Mounjaro® vs. metformin: How do they work?
Both medications were designed to treat type 2 diabetes and help regulate blood sugar in different ways. Let’s briefly take a look at where they come from and how they work.
Mounjaro®
Mounjaro® contains tirzepatide, which belongs to the GLP-1 receptor agonist family. This means it mimics hormones that regulate appetite, helping people feel fuller for longer while regulating blood sugar. It was developed by pharmaceutical company Eli Lilly and FDA-approved for the treatment of type 2 diabetes in May 2022.
Mounjaro® targets two different hormone receptors, GIP and GLP-1, making it more effective than traditional GLP-1 medications. For comparison, medications with semaglutide (Ozempic® and Wegovy®) target only GLP-1.
Because of its strong weight-loss effects, tirzepatide was later approved under the name Zepbound® for weight loss. Still, many people are prescribed the Mounjaro® version for off-label weight loss. (FYI, both medications have tirzepatide in the exact same doses; the only difference is the brand name and FDA approvals.)
How does Mounjaro® work? The tirzepatide in Mounjaro® binds with GLP-1 and GIP receptors in your digestive tract, pancreas, and brain. By activating these receptors, tirzepatide helps people feel fuller for longer, slows down stomach emptying, and regulates blood sugar, leading to better blood sugar control and reduced food intake.
How do you take Mounjaro®? Mounjaro® is taken as a once-weekly injection under the skin, typically in the thigh, abdomen, or upper arm. You can take it at any time of day, with or without food, but consistency is key. It’s best to stick to the same day each week to keep your routine on track.
Metformin
Metformin has been a trusted treatment for type 2 diabetes since it was approved by the FDA in 1995 and remains one of the most widely prescribed diabetes medications worldwide. Thanks to its long-standing track record, low cost, and strong safety profile, metformin is often the first medication doctors recommend for people newly diagnosed with type 2 diabetes.
One of the reasons metformin is so accessible is that it’s available as a generic medication, which significantly helps keep costs down. It’s effective, generally well-tolerated, and even offers a few added perks like modest weight loss and potential heart health benefits.
How does metformin work? Metformin doesn’t directly affect appetite or digestion like a GLP-1. Instead, it reduces the amount of glucose your liver produces, improves insulin sensitivity in muscles, and slows down the absorption of sugar from food.
How do you take metformin? You take metformin as a pill by mouth, usually a couple of times a day, but that depends on the formulation. Metformin comes in two versions:
- Immediate-release (IR): Needs to be taken two or three times daily.
- Extended-release (ER): Releases gradually, allowing for once-daily dosing with fewer digestive side effects.
Mounjaro® vs. metformin: What are the differences?
Mounjaro® and metformin both help manage blood sugar and can support weight loss to different degrees, but they do so in very different ways. Understanding their dosing, administration, price, insurance coverage, and availability can help you decide which option aligns best with your needs.
You take them differently
One of the most obvious differences between Mounjaro® and metformin is how each one is taken.
- Mounjaro® is a once-weekly, self-administered injection that gradually increases in dosage over time to help your body adjust and improve results.
- Metformin is a pill that you swallow once to several times a day, depending on the form, IR or ER. The dose will also increase gradually depending on how you respond to it.
Pricing and insurance coverage vary
Prices vary widely between Mounjaro® and metformin, and insurance coverage can make a big difference in what you actually pay out of pocket. Here’s how the two compare when it comes to affordability and coverage:
- Mounjaro® can cost over $1,000 per month without insurance. Some insurance plans cover it if you’re prescribed it for type 2 diabetes, but coverage for weight loss is unlikely. Manufacturer savings programs might help reduce costs.
- Metformin is one of the most affordable diabetes medications, largely because it’s widely offered as a generic. For those paying out of pocket, prices can be as low as $4 to $20 per month. Most insurance plans cover it with little to no copay. However, brand-name versions or extended-release (ER) formulations may cost more, especially without insurance.
One is available as a generic medication
Whether or not a medication has a generic version can make a big difference in both cost and accessibility. Generic drugs are just as effective as their brand-name counterparts but come at a much lower price point. Here’s how Mounjaro® and metformin compare in terms of generic availability:
- Mounjaro® doesn’t have a generic version because tirzepatide is still under patent protection. That means only Eli Lilly, the pharmaceutical company that developed it, has the exclusive rights to manufacture and sell the drug. Patents are typically granted to protect new medications for a set period, usually 20 years from the date of filing, to give the company time to recoup research and development costs.
- Metformin is widely available in generic form, making it affordable and accessible, even for those without insurance.
Mounjaro® vs. metformin: What are the similarities?
While Mounjaro® and metformin work in different ways, they share some similarities, such as:
They were both designed for diabetes management
Both medications improve insulin sensitivity and lower blood sugar levels, making them effective for treating type 2 diabetes. They help your body use insulin more efficiently while reducing excess glucose production.
May cause digestive side effects
While they have very different side effect profiles overall, both medications can lead to stomach-related side effects, especially when first starting. Nausea, bloating, and diarrhea are common, but these often improve over time as your body adjusts.
Mounjaro® vs. metformin: Which is better for weight loss?
Mounjaro® and metformin both offer weight loss benefits, but their effectiveness, cost, and sustainability differ. Studies show that Mounjaro® results in more impressive weight loss, but how much weight you can potentially lose isn’t the only factor to consider. Your budget and lifestyle preferences will also play a big role in choosing between these medications. Mounjaro® is much more expensive than metformin, and people tend to stay on these medications for several years.
Mounjaro® vs. metformin: How much weight can you lose?
If you’re considering Mounjaro® or metformin for weight loss, clinical trials show some clear differences between the two.
- Mounjaro® (tirzepatide):
- People taking the highest dose of Mounjaro® (15 mg) lost an average of 21% of their body weight over 72 weeks.
- Even at lower doses (5 mg and 10 mg), average weight loss ranged from 15% to 17% of body weight over the same period.
- Metformin:
- People taking metformin lost an average of 5% of their body weight when combined with lifestyle changes.
How long does it take to see results?
Medications like Mounjaro® or metformin can lead to varying timelines and degrees of weight loss. Understanding what to expect can help set realistic goals and maintain motivation.
Mounjaro® (tirzepatide):
- 3 months: An average of 7% to 8% of body weight
- 12+ months: An average of nearly 21% reduction in body weight.
Metformin:
- 3 months: Weight loss varies.
- 12+ months: An average of 3 to 5%.
Every person responds differently to medication, with factors like genetics, diet, exercise habits, and consistency playing a major role. While both medications can support weight loss, integrating healthy eating and regular physical activity can significantly improve long-term success.
Working with a healthcare provider to tailor a plan that aligns with your goals and medical history is essential. Medications can be a helpful tool, but lasting results come from building sustainable lifestyle habits that support your overall well-being.
Can you switch between Mounjaro® and metformin?
Yes, it is possible to switch between Mounjaro® and metformin, but because these medications work differently, the transition can affect your appetite, weight loss progress, and blood sugar control. Understanding how your body may respond to the change is key to making a smooth adjustment.
When transitioning between these medications, you might experience shifts in appetite, digestion, and insulin response. Since Mounjaro® helps regulate hunger by mimicking gut hormones, and metformin focuses more on improving insulin sensitivity, switching between them may require some adjustments to maintain steady blood sugar levels.
- Switching from Mounjaro® to metformin – You might notice an increase in hunger since metformin does not directly curb appetite the way Mounjaro® does. Weight loss could slow down or stabilize, but metformin still supports metabolic health and can help maintain results when paired with lifestyle changes.
- Switching from metformin to Mounjaro® – You may experience a decrease in appetite and a more significant reduction in weight due to Mounjaro®’s effects on digestion and hunger regulation. Some people report mild nausea or digestive discomfort at first, but this typically improves over time.
If you’re making this transition, having a structured plan—such as a weight loss or nutrition program like Noom offers—can provide valuable support in adapting to the changes effectively. Your healthcare provider can decide whether switching is the right move for you. They can help assess your weight loss goals, blood sugar levels, and overall well-being to ensure you’re on the best path forward.
Who can get a prescription for Mounjaro® or metformin for weight loss?
If you’re considering Mounjaro® or metformin as part of your weight loss journey, eligibility largely depends on BMI and any related conditions.
Here’s who might be a good fit for these medications:
- Adults with a BMI of 30 or higher
- Adults with a BMI of 27 or higher with weight-related health conditions such as high blood pressure or high cholesterol.
- In some cases, people with a BMI of 25 or higher may qualify for metformin, especially if they have insulin resistance, PCOS, or prediabetes.
Who can’t take Mounjaro® or metformin for weight loss?
While Mounjaro® and metformin can help some people lose weight, they’re not the right fit for everyone, especially those with certain preexisting conditions. If you’re considering either medication, it’s important to know who should avoid them due to safety concerns.
Who should avoid Mounjaro®?
- People with a history of medullary thyroid carcinoma (MTC) or multiple endocrine neoplasia syndrome type 2 (MEN 2)
- Anyone allergic to tirzepatide or any ingredients in Mounjaro®
- People who are pregnant, trying to conceive, or breastfeeding
Talk to your doctor if you have:
- Severe gastrointestinal conditions
- A history of pancreatitis
Who should avoid metformin?
- People with severe kidney disease or advanced kidney problems
- Those with liver disease or a history of alcohol abuse
- Anyone with a history of lactic acidosis
- People with severe heart failure
- People who are pregnant or breastfeeding
If you’re considering Mounjaro® or metformin for weight loss, your healthcare provider will decide if these medications are safe for you. Your doctor will weigh the benefits and risks, ensuring that your treatment plan aligns with your overall health goals.
Can you take metformin and Mounjaro® together?
Yes, metformin and Mounjaro® can be taken together. In fact, many doctors prescribe metformin and Mounjaro® together for diabetes treatment, as they work differently to regulate blood sugar and enhance weight loss. If using Mounjaro® vs. metformin for insulin resistance is the main concern, both options offer benefits:
- Metformin improves insulin sensitivity and lowers glucose production in the liver.
- Mounjaro® helps suppress appetite, slow digestion, and enhance insulin release in response to meals.
Taking metformin with Mounjaro® may help enhance weight loss results, but the impact varies. Studies on tirzepatide showed substantial weight loss even without metformin. However, research shows that when used together, these medications might provide better weight loss results.
If you’re considering using both medications, talk to your doctor about whether this approach fits your health needs. They can help determine the right dose and timing to maximize benefits while minimizing side effects.
If you take metformin or Mounjaro® to lose weight, will you need to keep taking them forever?
How long you take Mounjaro® or metformin depends on your personal health goals and how your body responds. Some people use these medications for a year or more to help with weight loss and metabolic health, while others may take them indefinitely.
If you decide to stop either medication, you might notice some changes in your body, especially if you haven’t built sustainable lifestyle habits. Here’s what happens when you stop taking these medications:
- Mounjaro®: Since it works by controlling appetite and slowing digestion, stopping it may lead to increased hunger and potential weight regain. Clinical studies show that people who discontinue GLP-1 medications without maintaining diet and exercise habits tend to regain a significant portion of their lost weight within a year.
- Metformin: While it doesn’t suppress appetite as strongly as Mounjaro®, metformin improves insulin sensitivity. Stopping it could result in higher blood sugar levels, which may make it harder to maintain weight loss if you have underlying metabolic concerns.
Do you need to taper off Mounjaro® or metformin?
Since it doesn’t cause dependence, tapering isn’t always necessary for Mounjaro®. Your doctor may gradually lower your dose instead of stopping suddenly to minimize any sudden increase in hunger.
On the other hand, most people can stop metformin without tapering, but your doctor might adjust your dose over time if it has been helping regulate your blood sugar.
No matter which medication you take, lasting weight comes from focusing on healthy eating, movement, and behavior changes. Noom can help you develop sustainable habits, ensuring that even if you stop taking Mounjaro® or metformin, you maintain your progress and continue feeling your best.
Metformin vs. Mounjaro®: Costs and insurance
When trying to decide between Mounjaro® and metformin, price is often a big part of the decision. Metformin is one of the most affordable options out there, while Mounjaro® can be much more expensive if it’s not covered by insurance. Here’s how the costs compare:
The cost of metformin
Metformin is affordable for more people. It’s often covered by insurance for diabetes management. While it won’t likely be covered for off-label weight loss, generic versions are widely available and cost as little as $4 to $20 per month. Branded versions like Glucophage XR can cost over $100 per month. Some people may require branded metformin due to issues with the immediate-release formula.
Other insurance considerations: Most private insurance plans, Medicare, and Medicaid cover generic metformin at a very low cost, often under $10 per month. Branded versions may require a higher copay. Metformin is also typically covered under Medicare Part D with low out-of-pocket costs. Read more about the costs of metformin.
The cost of Mounjaro®
Without insurance, Mounjaro® costs about $1,080 per month, making it a costly option for those paying out of pocket.
Insurance considerations: If prescribed for type 2 diabetes, it may be covered but will require prior authorization and come with a higher copay. If prescribed off-label for weight loss, insurance coverage is less likely. Medicare currently does not cover Mounjaro® for weight loss, but it may be covered for type 2 diabetes management. Read more about the cost of Mounjaro®.
Mounjaro® vs. metformin: Side effects and safety considerations
Both Mounjaro® and metformin come with potential side effects. While some are mild and temporary, others are more serious and require medical attention. Let’s go through everything you should discuss with your doctor.
Common side effects: Mounjaro® & metformin
For both medications, these side effects are typically mild and often improve as your body adjusts to the medication or an increased dose.
Side effects of Mounjaro®
- Nausea
- Vomiting
- Diarrhea or constipation
- Stomach pain
- Fatigue
Side effects of Metformin
- Nausea
- Diarrhea
- Stomach pain
- Loss of appetite
- Metallic taste in the mouth
For a full breakdown of potential risks, read more about the safety of Mounjaro® and metformin.
Rare but severe side effects
Both medications are associated with rare but serious side effects that require immediate medical attention. Here’s a list to bring up with your doctor:
Rare Mounjaro® side effects
- Pancreatitis: Be alert for persistent stomach pain, especially if it radiates to your back.
- Allergic reactions: Symptoms include swelling of the face, lips, tongue, or throat; difficulty breathing or swallowing; severe rash or itching; dizziness; or a rapid heartbeat.
- Vision changes: Get any sudden vision changes checked immediately.
- Low blood sugar (hypoglycemia): If you have diabetes and use medications like insulin or other blood sugar-lowering drugs, watch for symptoms like dizziness, shakiness, sweating, or confusion.
- Kidney problems: Symptoms like swelling, fatigue, shortness of breath, or changes in urination could signal kidney issues, especially if dehydration occurs from nausea, vomiting, or diarrhea.
- Thyroid tumors: Watch for lumps or swelling in your neck, hoarseness, difficulty swallowing, or shortness of breath. Animal studies have shown a potential link between tirzepatide and thyroid tumors, but these types of tumors haven’t been reported in people.
- Depression or suicidal thoughts: If you notice new or worsening mental health symptoms, seek help immediately.
Rare metformin side effects
- Lactic acidosis: Drinking alcohol while taking metformin can result in a rare but serious condition where acid builds up in the bloodstream, leading to symptoms like extreme fatigue, muscle pain, shortness of breath, or confusion.
- Kidney issues – Watch for changes in urination, swelling in the legs, fatigue, or confusion.
- Vitamin B12 deficiency – Long-term metformin use can lower B12 levels, leading to fatigue, numbness, tingling in the hands and feet, pale/yellowish skin, and memory loss.
Mounjaro® vs. metformin: Dosage and administration
Taking your medication correctly is always important for getting the best results. Here’s how Mounjaro® and metformin are typically prescribed and adjusted over time.
Mounjaro® (tirzepatide)
Mounjaro® is taken as a once-weekly injection that you administer yourself with a prefilled injection pen. You’ll inject yourself just under the skin in the stomach, thigh, or upper arm on your day of choice.
The medication is started at a low dose and gradually increased over time—a process known as titration. Your healthcare provider will begin with the lowest dose and adjust it based on how well you’re tolerating it and how your blood sugar or weight is responding. The slow dose escalation helps your body adjust and minimizes potential side effects like nausea or digestive discomfort.
- Starting dose: 2.5 mg weekly for the first four weeks, though some remain on this dose if weight loss is steady and side effects are low.
- Dose increases: When you’re ready, the dose is increased to 5 mg weekly. If additional blood sugar control or weight loss is needed, your provider may gradually increase the dose in 2.5 mg increments every four weeks (7.5 mg, 10 mg, 12.5 mg, 15 mg).
- Maximum dose: The maximum dose is 15 mg weekly.
Metformin
Metformin is taken as a daily oral medication with meals to reduce stomach upset. It’s available in immediate-release (IR) and extended-release (ER) forms. The IR version releases the medication into your system all at once and is usually taken two or three times per day. The ER version releases the drug more slowly throughout the day, allowing for once-daily dosing.
Like Mounjaro®, you start metformin at the lowest dose and it’s gradually increased to help minimize side effects. This slow and steady approach helps your body adjust.
- Starting dose: Typically 500 mg once or twice daily. Some doctors start lower to ease digestion issues.
- Dose increases: Your provider may increase the dose by 500 mg, depending on how well your body tolerates it.
- Maximum dose: 2,500 mg daily, divided into two or three doses throughout the day.
Which is right for me when choosing between metformin or Mounjaro®?
Deciding between metformin and Mounjaro® depends on factors like your weight loss goals, budget, lifestyle, and overall health needs. Your choice depends on what fits best with your lifestyle, budget, and health needs. Here’s a quick breakdown of everything we’ve gone through to help you compare:
| Medication | Metformin | Mounjaro® |
|---|---|---|
| Approvals and uses | FDA-approved for the treatment of type 2 diabetes; off-label for weight loss and polycystic ovary syndrome (PCOS) | FDA approved for the treatment of type 2 diabetes; off-label for weight loss |
| Effectiveness | Average of 5% of body weight | Average of 21% of body weight |
| How you take it | By mouth twice a day | Weekly injection with a prefilled pen |
| Common side effects | Nausea, diarrhea, stomach pain, loss of appetite, metallic taste in the mouth | Nausea, vomiting, diarrhea, or constipation, stomach pain, fatigue |
| Pricing per month (without insurance) | Price ranges from $4 to $20 per month for generic medication. Branded medication costs more. Read more about the costs of metformin | List price of $1,080 per month Read more about the cost of Mounjaro®. |
| Insurance coverage | Almost always covered for diabetes; unlikely for weight loss | Sometimes covered for type 2 diabetes; unlikely for weight loss |
Alternatives to Mounjaro® and metformin
If Mounjaro® and metformin aren’t right for you, there are several other medications that can help support weight loss. Each option works differently, so the best choice depends on your individual health needs, goals, and how your body responds.
GLP-1 receptor agonists
| Medication | Brand names and uses | Cost per month (without insurance) | Effectiveness | How it’s taken |
|---|---|---|---|---|
| Tirzepatide – GLP-1/GIP receptor agonist – Contains the same active ingredient as Mounjaro® | Zepbound®: weight loss and obstructive sleep apnea (OSA) | Zepbound®: Pens: $1,087 Vials: $349 (2.5 mg) $499 (5 mg, 7.5 mg, 10 mg) Learn more | People lost an average of 21% of body weight at 72 weeks. | Weekly injection |
| Semaglutide – GLP-1 receptor agonist | Ozempic®: type 2 diabetes, off-label weight loss Wegovy®: weight loss and heart disease Rybelsus®: type 2 diabetes, off-label weight loss | Ozempic®: $998 Learn more Wegovy®: $1,350 $499 (NovoCare Pharmacy) Learn more Rybelsus®: $998 Learn more | Ozempic® and Wegovy®: People lost an average of 15% of body weight in 68 weeks with injectable semaglutide Rybelsus®: People lost about 4% of their body weight | Ozempic® and Wegovy®: Weekly injection Rybelsus®: Daily pill |
| Liraglutide – GLP-1 receptor agonist | Victoza®: type 2 diabetes, off-label weight loss Saxenda®: weight loss and heart disease Generic liraglutide: type 2 diabetes, off-label weight loss | Victoza®: $800 to $1,400 Saxenda®: $1,350 Learn more. Generic liraglutide: $470 – $700 | People lost an average of 5-6% of body weight in one year. | Daily injection |
Other medications
GLP-1s aren’t the only options. These medications work in different ways and can be prescribed to help people lose weight if needed.
| Medication | Brand names | Cost per month (without insurance) | Effectiveness | How it’s taken |
|---|---|---|---|---|
| Phentermine | Lomaira®, Adipex-P® | $27-$100 | About 80% of people with a BMI of 30 or more lost at least 5% of their body weight in 6 months. | Daily pill |
| Diethylpropion | Tenuate®, Tenuate Dospan® | $40-$85 | People lost an average of 10% of their body weight in 6 months. | Pill taken one to three times daily |
| Naltrexone and bupropion | Contrave® | $600-$800CurAccess™: $99 | People lost an average of 7 to 8% of their body weight in a year. | Pill taken up to twice daily |
| Orlistat | Xenical®, Alli® | $50-$800 | People in a study lost about 10% of body weight after taking Orlistat for 1 year. | Pill taken three times daily with meals. |
Choosing the right weight loss medication
Choosing between Mounjaro® and metformin for weight loss and diabetes management is a deeply personal decision, one that depends on your health needs, lifestyle, and goals. While Mounjaro® shows impressive weight loss results in clinical trials, metformin remains a cost-effective treatment that offers modest weight loss benefits and strong blood sugar regulation without the need for injections.
Ultimately, the best medication is the one that fits your unique health profile and long-term goals. And if you’re wondering whether you can take both, yes, many people do, as they work in complementary ways to improve metabolic health. But regardless of which medication you choose, lifestyle changes play a critical role in long-term success.
No matter where you are on your journey, support makes all the difference. Sustainable weight loss and improved metabolic health require more than just a prescription—they need a plan tailored to your unique needs. Whether you’re just starting with metformin, considering Mounjaro®, or combining both, having the right tools and guidance can set you up for long-term success. Talk to your healthcare provider about your best treatment plan, and focus on making small, meaningful lifestyle changes that will help you feel your best for years to come.
Mounjaro®, metformin, Ozempic®, and Victoza® are not FDA-approved to treat obesity or for weight loss.
