Compare Metformin vs. Phentermine

Metformin (Glumetza, Riomet) and phentermine (Adipex-P) are both oral medications that may help with weight loss, but they serve different purposes. Metformin is a biguanide used to manage Type 2 diabetes by lowering blood sugar levels and improving insulin use in the body. Phentermine, on the other hand, is a sympathomimetic stimulant used for short-term weight management in adults with a high body mass index (BMI). While metformin is not a controlled substance, phentermine is a Schedule IV controlled substance due to its potential for misuse and dependence. Metformin is typically taken once or twice daily, with doses adjusted based on blood sugar levels, while phentermine is usually taken once daily in the morning. Metformin is available in both liquid and tablet forms, including a long-acting version, whereas phentermine comes in tablets, capsules, and orally disintegrating tablets. Common side effects of metformin include diarrhea and nausea, while phentermine can cause dry mouth and trouble sleeping. Additionally, metformin can lead to lactic acidosis in rare cases, especially in people with kidney problems, whereas phentermine can raise blood pressure and heart rate.