Phentermine is a medicine intended for the efficient treatment of obesity. It is supposed to be combined with diet and exercise for optimum effect. Do not take it in larger doses or for longer that your doctor prescribed, as people taking phentermine have reported addiction. Your dose should be carefully observed to make sure you take the exact amount prescribed for your condition. Make sure your doctor knows about any other drugs you are currently taking. You need to mention the following medicines that may alter the effects of phentermine or make it less efficient: fluoxetine, fluvoxamine, MAO inhibitors, insulin, paroxetine, any other medications for the treatment of depression, or any vitamins or supplements.

In some patients this drug can cause drowsiness. Make sure you do not operate machinery if you are not sure what effects phentermine has on, you or you know that it can make you drowsy. Drinking alcohol is not recommended as it can worsen some of the side effects and add to the drowsiness you experience. Some of the most common side effects you may experience when taking phentermine include dry mouth, diarrhea, vomiting, constipation and unpleasant taste in your mouth. More serious symptoms that you must report immediately include dizziness, insomnia, tremor, swelling, shortness of breath and restlessness.