Phentermine side effects

Get emergency medical help if you have any of these signs of an allergic reaction to phentermine: hives; difficulty breathing; swelling of your face, lips, tongue, or throat. Call your doctor at once if you have a serious side effect such as:

• 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;
  
• confusion or irritability, unusual thoughts or behavior;
  
• feelings of extreme happiness or sadness; or
  
• dangerously high blood pressure (severe headache, blurred vision, buzzing in your ears, anxiety, confusion, chest pain, shortness of breath, uneven heartbeats, seizure).
  

Less serious phentermine side effects may include:

• feeling restless or hyperactive;
  
• headache, dizziness, tremors;
  
• sleep problems (insomnia);
  
• dry mouth or an unpleasant taste in your mouth;
  
• diarrhea or constipation, upset stomach; or
  
• increased or decreased interest in sex, impotence.