What should I avoid while taking phentermine?
Avoid driving or hazardous activity until you know how phentermine will affect you. Your reactions could be impaired.
Drinking alcohol with this medicine can cause side effects.
Phentermine side effects
Get emergency medical help if you have signs of an allergic reaction to phentermine: hives; difficult breathing; swelling of your face, lips, tongue, or throat.
Call your doctor at once if you have:
- feeling short of breath, even with mild exertion;
- chest pain, feeling like you might pass out;
- swelling in your ankles or feet;
- pounding heartbeats or fluttering in your chest;
- tremors, feeling restless, trouble sleeping;
- unusual changes in mood or behavior; or
- increased blood pressure – severe headache, blurred vision, pounding in your neck or ears, anxiety, nosebleed.
Common phentermine side effects may include:
- dizziness, headache;
- dry mouth, unpleasant taste;
- diarrhea, constipation, stomach pain; or
- increased or decreased interest in sex.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
What other drugs will affect phentermine?
Taking phentermine together with other diet medications such as fenfluramine (Phen-Fen) or dexfenfluramine (Redux) can cause a rare fatal lung disorder called pulmonary hypertension. Do not take phentermine with any other diet medications without your doctor’s advice.
Many drugs can interact with phentermine. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed here. Tell your doctor about all your current medicines and any medicine you start or stop using.