Phentermine is a prescription medicine used to reduce appetite and support weight loss. It is typically used as part of a comprehensive weight-loss plan that includes healthy eating, physical activity, and behavior changes. Phentermine is a Schedule 4 drug, indicating a potential for misuse, though the rate of misuse is low.

Phentermine acts as an indirect-acting sympathomimetic agent by releasing noradrenaline from presynaptic vesicles in the lateral hypothalamus. This increases noradrenaline concentration in the synaptic cleft, stimulating beta2-adrenergic receptors, which reduces hunger signals and increases energy expenditure.

When taking phentermine, expect a reduced appetite and increased feeling of fullness, leading to weight loss. Some side effects like dry mouth, unpleasant taste, or constipation may occur but often subside as the body adjusts to the medication.