By all means listen to your doctor, Phentermine is a stimulant that is similar to an amphetamine. Phentermine is an appetite suppressant that affects the central nervous system.
Phentermine can cause side effects that may impair your thinking or reactions. Be careful if you drive or do anything that requires you to be awake and alert. Avoid drinking alcohol. It can increase some of the side effects of phentermine. Phentermine may be habit-forming and should be used only by the person it was prescribed for. Keep track of how many pills have been used from each new bottle of this medicine. Phentermine is a drug of abuse and you should be aware if any person in the household is using this medicine improperly or without a prescription.
You may have withdrawal symptoms, such as depression and extreme tiredness, when you stop using phentermine after using it over a long period of time. Do not stop using phentermine suddenly without first talking to your doctor. You may need to use less and less before you stop the medication completely.
Serious side effects:
chest pain, swelling in your ankles or feet, feeling light-headed, fainting, or feeling short of breath, even with mild exertion;
fast or uneven heartbeat;
unusual thoughts or behavior, feeling restless or confused; or
increased blood pressure (severe headache, blurred vision, trouble concentrating, chest pain, numbness, seizure).
Less serious side effects may be more likely to occur, such as:
feeling nervous or anxious;
headache, dizziness, tremors;
trouble sleeping (insomnia);
dry mouth or an unpleasant taste in your mouth;
diarrhea or constipation; or
itching.
If you have any other questions on this drug, please speak with your doctor about it.
Good luck and best wishes.