Can You Take Phentermine with Mounjaro?
Key takeaways:
Phentermine (Adipex-P, Lomaira) is an oral medication that’s FDA approved for weight loss in certain people age 17 and older. Mounjaro (tirzepatide) is an injectable medication approved to treat Type 2 diabetes in adults. Mounjaro is sometimes prescribed off-label for weight loss.
There are no available studies on the safety or effectiveness of taking phentermine and Mounjaro together. Phentermine’s labeling warns against combining it with other weight-loss medications. But it’s possible that a healthcare professional may still recommend this combination in certain cases.
Both phentermine and Mounjaro can cause digestive-related side effects. Taking both medications may increase your risk of experiencing these effects. But more research is needed to confirm if this is the case.
Access savings on related medications
Table of contents
Phentermine (Adipex-P) is an oral weight-loss medication. It’s been available for several decades and is an effective option for short-term weight loss.
Mounjaro (tirzepatide) is an injectable medication that’s FDA approved to treat Type 2 diabetes in adults. During its clinical trials, people reported significant weight loss in addition to lower blood sugar (glucose) levels while using the medication. This weight-loss effect has led to healthcare professionals prescribing Mounjaro off-label for weight loss.
But when it comes to weight loss, does combining medications lead to greater results? Or what about if you’re taking Mounjaro for Type 2 diabetes and are looking for additional help with weight loss? Below, we’ll discuss whether you can take phentermine with Mounjaro.
Good to know: The active ingredient in Mounjaro (tirzepatide) is approved for weight loss under the brand name Zepbound. Despite Zepbound’s availability, Mounjaro is still commonly prescribed off-label for weight loss.
What are phentermine and Mounjaro used for?
Phentermine is a once-daily oral medication that’s FDA approved for short-term (up to 12 weeks) weight loss. But evidence suggests that taking it long term may also be safe. Phentermine is approved for use in people age 17 and older who meet certain body mass index (BMI) criteria:
BMI of at least 30, or
BMI of at least 27 who also have a weight-related health condition, such as high blood pressure or Type 2 diabetes
Mounjaro is a once-weekly injection that’s approved to treat Type 2 diabetes in adults. As mentioned above, it’s commonly used off-label for weight loss. Mounjaro is intended to be used long term, regardless of whether you’re taking it for diabetes or weight loss.
Both phentermine and Mounjaro work best when combined with diet and exercise changes. It’s best to discuss these lifestyle changes with your prescriber. They can take your health history and personal goals into account when making recommendations.
Can you take phentermine with Mounjaro?
Probably not. The combination of phentermine and Mounjaro hasn’t been studied for safety or effectiveness. In fact, phentermine’s labeling warns against combining it with other weight-loss medications due to a possible increased risk of side effects.
How does phentermine work? Learn how effective phentermine is and how it works, and get answers to other frequently asked questions.
How does Mounjaro work? Mounjaro mimics two gut hormones, which helps balance blood glucose levels. Read about how Mounjaro works here.
A holistic approach: Combining medication with lifestyle changes can enhance your weight-loss progress. Here, one person shares how a new diet and mindset helped keep him at his ideal weight.
That being said, some healthcare professionals may still recommend combining phentermine and Mounjaro for certain people. This would only be done if your prescriber feels that the potential benefits of the combination outweigh the risks for you.
When would a healthcare professional recommend taking phentermine with Mounjaro?
It’s hard to say when a healthcare professional would recommend taking phentermine and Mounjaro together. As mentioned, this combination hasn’t been studied for safety or effectiveness. So we don’t know for sure if certain people are more likely to benefit from taking both than others.
One time this combination might be considered is if you’re using Mounjaro for diabetes but haven’t met your weight-loss goals. In this instance, experts say adding a weight-loss medication could be an option. But it’s not right for everyone.
What are the benefits of combining phentermine and Mounjaro?
There are no studies that confirm the benefits of combining phentermine and Mounjaro. But it’s possible you may lose more weight. Both medications can decrease your appetite, which may cause you to eat fewer calories.
Studies show most people taking phentermine lose at least 5% of their body weight. And many lose at least 10%.
In one clinical trial, people using Mounjaro for Type 2 diabetes lost an average of 8% to 11% of their starting body weight. Another clinical trial looked at people who are considered obese but don’t have diabetes who used tirzepatide (Mounjaro’s active ingredient) for weight loss. In this study, people lost an average of 15% of their body weight.
Keep in mind that there’s no studies showing how much weight you might lose if you’re taking both phentermine and Mounjaro.
What are the risks of mixing phentermine and Mounjaro?
Each of these medications carries its own risks and side effects. So combining phentermine and Mounjaro may make side effects more likely. As discussed above, there are no safety studies that define the risks of this combination.
The table below shows side effects that phentermine and Mounjaro can both cause, as well as ones unique to each medication.
| Side effects phentermine and Mounjaro share | Side effects unique to phentermine | Side effects unique to Mounjaro |
|---|---|---|
Common:
Rare:
|
Common:
Rare:
|
Common:
Rare:
|
Mounjaro also slows the passage of things in your gut. This action could potentially change how your body absorbs oral medications, including phentermine. Due to a lack of research, we don’t know if this could negatively affect how phentermine works, or whether it raises the risk of side effects.
The bottom line
Phentermine (Adipex-P, Lomaira) is an oral weight-loss medication that’s FDA approved for short-term use in people age 17 and older. Mounjaro (tirzepatide) is an injection that’s approved to treat Type 2 diabetes in adults. It’s sometimes prescribed off-label for weight loss.
Most people wouldn’t take both phentermine and Mounjaro. In fact, phentermine’s labeling warns against combining it with other weight-loss medications. But it’s possible that a healthcare professional may still suggest taking both for some people.
There are no studies about whether combining phentermine and Mounjaro is safe or effective. So be sure to discuss the risks and benefits of this combination with your prescriber if they recommend you take both.
Why trust our experts?
References
Advanced Rx Pharmacy of Tennessee, LLC. (2022). Phentermine HCl- phentermine hcl tablet [package insert].
American Diabetes Association Professional Practice Committee. (2023). 8. Obesity and weight management for the prevention and treatment of type 2 diabetes: Standards of care in diabetes–2024.
Eli Lilly and Company. (2021). Lilly's Surpass-1 results published in The Lancet show tirzepatide's superior A1C and body weight reductions versus placebo in adults with type 2 diabetes.
Eli Lilly and Company. (2024). Mounjaro- tirzepatide injection, solution [package insert].
Jastebroff, A. M., et al. (2022). Tirzepatide once weekly for the treatment of obesity. The New England Journal of Medicine.
Lewis, K. H., et al. (2019). Safety and effectiveness of longer-term phentermine use: Clinical outcomes from an electronic health record cohort. Obesity.
