Key takeaways
Phentermine (Adipex-P) and tirzepatide (Mounjaro) are both medications that can be used to help with weight management, but they work in different ways and are used for different primary purposes. Phentermine is a sympathomimetic stimulant that suppresses appetite and is FDA-approved for short-term weight management in adults with a body mass index (BMI) of 30 m/kg² or greater, or 27 kg/m² or greater with at least one weight-related condition. It is taken orally, usually once a day, and is available as a generic medication. Common side effects include dry mouth, trouble sleeping, and headache. Tirzepatide, on the other hand, is a glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide-1 (GLP-1) receptor agonist primarily approved for improving blood sugar control in adults with Type 2 diabetes. It is administered as a weekly subcutaneous injection and is only available as a brand-name medication. Common side effects include nausea, vomiting, and diarrhea. While tirzepatide is not FDA-approved for weight loss under the brand Mounjaro, it has been approved for weight management under the brand name Zepbound. Phentermine is a controlled substance due to its potential for misuse, whereas tirzepatide is not. Additionally, phentermine should not be combined with other weight loss medications, and it has more restrictions regarding use in people with certain health conditions, such as heart problems.
