What are the side effects of phentermine?

As with all medications, people who take phentermine may suffer some side effects. These reactions range from mild to severe.

Common phentermine side effects include:

  • Dry mouth
  • Unpleasant taste in mouth
  • Constipation
  • Diarrhea
  • Headaches
  • Restlessness
  • Insomnia
  • Irritability
  • Tiredness
  • Low mood
  • Feelings of nervousness
  • Impotence
  • Changes in libido 

 Other possible side effects of phentermine may be more serious. 

If you experience any of the following, contact your doctor immediately:

  • Suspected allergic reaction (skin rash, itching, facial swelling, short breaths, tight chest)
  • Difficulty breathing
  • Swelling of the mouth, legs or feet
  • Racing heart beat
  • Fainting
  • Chest pains
  • Uncharacteristic behavior
  • Psychosis

To read more about potential reactions to this medication, visit our page on phentermine side effects.

If you’re uncomfortable with the prospect of these phentermine side effects, consider using an alternative to phentermine like Phen Caps. Supplements help you to lose weight by suppressing appetite and boosting energy levels, but don’t cause any side effects.