Take this medication exactly as it was prescribed for you. Do not take the medication in larger amounts, or take it for longer than recommended by your doctor. Follow the directions on your prescription label.
It is best to take phentermine on an empty stomach before breakfast, or at least 10 to 14 hours before bedtime. Do not take more phentermine for an increased effect. Taking too much of this medication can cause serious, life-threatening side effects. Do not crush, chew, break, or open an extended-release capsule. Swallow the pill whole. It is specially made to release medicine slowly in the body. Breaking or opening the pill would cause too much of the drug to be released at one time.
Phentermine should be taken only for a short time, such as a few weeks.