Phentermine Interactions

Phentermine can react with other medications, so patients should always be monitored for possible drug interactions while taking phentermine and instructed not to start, stop or change the dose of the medication without consulting a doctor first.

Serious interactions may occur if phentermine is combined with certain medications. Patients who have used other appetite suppressants, such as diethylpropion, sibutramine or ephedra (ma huang) within a year of considering phentermine use should consult their doctor before they begin taking phentermine.

MAO inhibitors (antidepressants) should not be taken with or within two weeks of taking phentermine as very serious (possibly fatal) interactions may occur. A patient’s doctor should also be informed if the patient is taking any kind of antidepressant, including TCAs, SSRIs or SNRIs, diabetes medications, stimulants or street drugs of any kind.

Drugs that have side effects like dizziness or sleepiness, including over the counter medications, sleeping pills, muscle relaxants, and prescription pain relievers can interact with phentermine and exacerbate side effects.

Patients should inform their doctor before taking phentermine if they are taking drugs that increase the risk of seizure. It is also advisable to check the labels on other medications, herbal supplements, and vitamin/mineral supplements (especially diet aids) for warnings that they may increase heart rate or blood pressure.

The safety of using such products with phentermine should be discussed with a doctor. Caffeine consumption can also exacerbate side effects of phentermine, so coffee, tea, cola and chocolate should be consumed in moderation while taking phentermine.