Phentermine Side Effects

Phentermine has side effects for some people that may include various gastrointestinal complaints, insomnia, dry mouth, nausea, vomiting or dizziness. In many cases, side effects are mild and disappear when the body adjusts to the drug. If side effects persist or get worse, a doctor should be notified to determine whether the benefits of taking phentermine outweigh the risk or discomfort of its side effects.

In rare cases, serious side effects occur. Patients should contact their doctor immediately if they experience rapid or irregular heartbeat, changes in mood or mental state, uncontrolled muscle movements or changes in sexual ability or interest.

If severe headache, slurred speech, seizure, changes in vision or weakness on one side of the body occurs, the patient should stop taking phentermine and immediately seek medical attention. Other very rare but serious (sometimes fatal) side effects may include lung or heart problems.

The risk for very serious side effects increases with prolonged or inappropriate use of the medication. Patients who experience chest pain, shortness of breath during exercise, weakness, fainting or swelling in the extremities should stop taking phentermine and notify their doctor. In addition, patients should seek immediate medical attention if they develop a rash, itching, swelling or severe dizziness since rare but serious allergic reactions are possible.