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 – blurred vision, pounding in your neck or ears, anxiety, nosebleed.
Common phentermine side effects may include:
- dizziness, headache;
- dry mouth, unpleasant taste;
- diarrhea, stomach pain; or
- increased or decreased interest in sex.