Phentermine is meant to be used an appetite suppressant, to help you control how hungry feel.

When using the capsule form of Phentermine to control your appetite, depending on your hunger needs, you can take either 15 milligrams or 37.5 milligrams of Phentermine in the morning before you would be eating breakfast. Starting out with the smaller dosage for a week, if you find that Phentermine is not controlling how hungry you feel you can increase to the 37.5 milligrams. Do not take more than the 37.5 milligrams at any one time to control your hunger. Phentermine can be taken in the morning or in the afternoon when you find that you are hungriest during the day to help curb your appetite.

Phentermine tablets are a longer lasting form of appetite control that can be taken in the morning or in the afternoon. Starting with a small dosage of 15 milligrams take daily for a week, Phentermine will curb your appetite to help you eat less during your day. If you find that you are still hungry, increasing your Phentermine to 37.5 milligrams, taken in the morning or in the afternoon when you are most hungry, the Phentermine tablets will control your appetite longer so you eat less during your worse hunger craving times of the day.
Keep this and all medications out of children's reach. Store away from heat and direct light. Do NOT store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down. Do NOT keep outdated medicine past the expiration date. Discarded medicine should be kept out of children's reach.