Take phentermine exactly as prescribed by your doctor
Usually take it once daily in the morning
Take it before breakfast or 1–2 hours after breakfast, as directed
Avoid taking it late in the day or at night
Swallow the tablet or capsule with water
Do not take more than the prescribed dose
Do not crush, chew, or split extended-release forms unless told to do so
Follow a reduced-calorie diet while taking it
Combine it with regular exercise as advised
Avoid alcohol unless your doctor says it is safe
Limit caffeine if it causes jitteriness or fast heartbeat
Do not use other weight-loss medicines unless approved by your doctor
Take it consistently at the same time each day
Keep regular follow-up appointments to monitor progress and side effects
Stop and contact your doctor if you develop chest pain, severe shortness of breath, or a racing heartbeat
Do not take it if you are pregnant, breastfeeding, or have been told not to use it
Use it only for the duration prescribed by your doctor