Phentermine

As of the last update, we have found no reported interactions between this medicine and specific foods, supplements, or other compounds. It is possible that unknown interactions exist. Taking medicines with meals, on an empty stomach, or with alcohol may influence their effects; refer to the Uses and Precautions tabs or to the manufacturers’ package information for details as this is not covered in Nutrient Interactions. If you take medication, always discuss the potential risks and benefits of adding a new supplement with your doctor or pharmacist.

Drug Interactions

Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.

This drug should not be used with certain medications because very serious interactions may occur. If you are taking or have taken other appetite-suppressant drugs in the past year (such as diethylpropion, ephedra/ma huang), tell your doctor or pharmacist before starting this medication.

Taking MAO inhibitors with this medication may cause a serious (possibly fatal) drug interaction. Avoid taking MAO inhibitors (isocarboxazid, linezolid, metaxalone, methylene blue, moclobemide, phenelzine, procarbazine, rasagiline, safinamide, selegiline, tranylcypromine) during treatment with this medication. Most MAO inhibitors should also not be taken for two weeks before treatment with this medication. Ask your doctor when to start or stop taking this medication.

Some products that may interact with this drug are: high blood pressure medicine (such as guanethidine, methyldopa), phenothiazines (such as prochlorperazine, chlorpromazine), other stimulants (including amphetamines, methylphenidate, street drugs such as cocaine or MDMA/"ecstasy").

Tell your doctor or pharmacist if you are taking other products that cause drowsiness such as opioid pain or cough relievers (such as codeine, hydrocodone), alcohol, marijuana (cannabis), drugs for sleep or anxiety (such as alprazolam, lorazepam, zolpidem), muscle relaxants (such as carisoprodol, cyclobenzaprine), or antihistamines (such as cetirizine, diphenhydramine).

Check the labels on all your medicines (such as allergy or cough-and-cold products) because they may contain ingredients that cause drowsiness. Ask your pharmacist about using those products safely.

Some products have ingredients that could raise your heart rate or blood pressure. Tell your pharmacist what products you are using, and ask how to use them safely (especially cough-and-cold products or diet aids).

Caffeine can increase the side effects of this medication. Avoid drinking large amounts of beverages containing caffeine (coffee, tea, colas) or eating large amounts of chocolate.

This medication may interfere with certain medical/lab tests (such as brain scan for Parkinson's disease), possibly causing false test results. Make sure lab personnel and all your doctors know you use this drug.

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Drug information is selected from data included with permission and copyrighted by First DataBank, Inc. This is a summary and does not contain all possible information about this product. For complete information about this product or your specific health needs, ask your healthcare professional. Always seek the advice of your healthcare professional if you have any questions about this product or your medical condition. This information is not intended as individual medical advice and does not substitute for the knowledge and judgment of your healthcare professional. This information does not contain any assurances that this product is safe, effective or appropriate for you.

This information is intended only for residents of the United States. Products sold under the same brand names in other countries may contain different ingredients.

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Information expires December 2025.