Generic Name: phentermine (FEN-ter-meen)
Brand Name: Adipex-P
Phentermine is used for:
Reducing weight in obese patients when used short-term and combined with exercise, diet, and behavioral modification.
Phentermine is an appetite suppressant. It works by helping to release certain chemicals in the brain that control appetite.
Do NOT use phentermine if:
- you are allergic to any ingredient in phentermine or other sympathomimetics (eg, pseudoephedrine)
- you are taking dexfenfluramine, fenfluramine, furazolidone, guanadrel, guanethidine, or have taken a monoamine oxidase inhibitor (MAOI) (eg, phenelzine) in the last 14 days
- you have moderate to severe high blood pressure, an overactive thyroid, glaucoma, heart or blood vessel disease, or severe narrowing of the blood vessels
- you are in an agitated state, or have a history of substance abuse
Contact your doctor or health care provider right away if any of these apply to you.
Before using phentermine:
Some medical conditions may interact with phentermine. Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:
- if you are pregnant, planning to become pregnant, or are breast-feeding
- if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
- if you have allergies to medicines, foods, or other substances
- if you have a brain or spinal cord disorder, hardening of the arteries, high blood pressure, diabetes, or high cholesterol or lipid levels
Some MEDICINES MAY INTERACT with phentermine. Tell your health care provider if you are taking any other medicines, especially any of the following:
- Dexfenfluramine, fenfluramine, furazolidone, or MAOIs (eg, phenelzine) because the risk of serious side effects, such as increasing headache, high blood pressure, slow heart rate, elevated temperature, or possibly fatal lung problems, may be increased
- Serotonin specific reuptake inhibitors (eg, fluoxetine) because the risk of their side effects may be increased by phentermine
- Guanadrel or guanethidine because their effectiveness may be decreased by phentermine
Ask your health care provider if phentermine may interact with other medicines that you take. Check with your health care provider before you start, stop, or change the dose of any medicine.
How to use phentermine:
Use phentermine as directed by your doctor. Check the label on the medicine for exact dosing instructions.
- Take phentermine about 30 minutes before a meal.
- Take your last dose of phentermine at least 4 to 6 hours before bedtime.
- If you are taking phentermine 1 time a day, take your dose in the morning.
- If you miss a dose of phentermine, take it as soon as possible. If it is after 12 pm and you are taking phentermine 1 time a day, or after 4 pm and you are taking it more than 1 time a day, skip the missed dose and go back to your regular dosing schedule. Do not take 2 doses at once.
Ask your health care provider any questions you may have about how to use phentermine.
Important safety information:
- Phentermine may cause dizziness. These effects may be worse if you take it with alcohol or certain medicines. Use phentermine with caution. Do not drive or perform other possibly unsafe tasks until you know how you react to it.
- Do NOT take more than the recommended dose or use for longer than prescribed without checking with your doctor. Doing so may increase the risk of serious side effects.
- Tell your doctor or dentist that you take phentermine before you receive any medical or dental care, emergency care, or surgery.
- Before you have any medical or dental treatments, emergency care, or surgery, tell your doctor or dentist that you are using phentermine.
- Avoid drinking alcohol with phentermine.
- Diabetes patients-Phentermine may affect your blood sugar. Check blood sugar levels closely. Ask your doctor before you change the dose of your diabetes medicine.
- Phentermine is not recommended for use in CHILDREN younger than 12 years old; safety and effectiveness in this age group have not been confirmed.
- PREGNANCY and BREAST-FEEDING: If you become pregnant, contact your doctor. You will need to discuss the benefits and risks of using phentermine while you are pregnant. It is not known if phentermine is found in breast milk. Do not breast-feed while taking phentermine.
After you have taken phentermine for a few weeks, it will usually not work as well as when you began taking it. This is known at TOLERANCE. Talk with your doctor if phentermine stops working well. Do not take more medicine than prescribed.
Some people who use phentermine for a long time may develop a need to continue taking it. People who take high doses are also at risk. This is known as DEPENDENCE or addiction. If you stop taking phentermine suddenly, you may have WITHDRAWAL symptoms. These may include extreme tiredness, mental depression, trouble sleeping, irritability, or mental, mood, or personality changes.
Possible side effects of phentermine:
All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome:
Seek medical attention right away if any of these SEVERE side effects occur:
Bad taste in mouth; changes in sex drive; constipation; diarrhea; difficulty sleeping; dizziness; dry mouth; exaggerated sense of well being; headache; impotence; nervousness; overstimulation; restlessness; sleeplessness; upset stomach.
Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); bizarre behavior; chest pain; fainting; fast heartbeat; pounding in the chest; shortness of breath; swelling of the legs and feet; tremor.
This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider. Call your doctor for medical advice about side effects. To report side effects to the appropriate agency, please read the Guide to Reporting Problems to FDA.
If OVERDOSE is suspected:
Contact 1-800-222-1222 (the American Association of Poison Control Centers), your local poison control center, or emergency room immediately. Symptoms may include confusion; diarrhea; nausea; rapid breathing; restlessness; stomach cramps; tremor; vomiting.Proper storage of phentermine:
Store phentermine at room temperature, between 59 and 77 degrees F (15 and 25 degrees C), in a tightly closed container. Store away from heat, moisture, and light. Do not store in the bathroom. Keep phentermine out of the reach of children and away from pets.
- If you have any questions about phentermine, please talk with your doctor, pharmacist, or other health care provider.
- Phentermine is to be used only by the patient for whom it is prescribed. Do not share it with other people.
- If your symptoms do not improve or if they become worse, check with your doctor.
- Check with your pharmacist about how to dispose of unused medicine.
This information should not be used to decide whether or not to take phentermine or any other medicine. Only your health care provider has the knowledge and training to decide which medicines are right for you. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about phentermine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to phentermine. This information is not specific medical advice and does not replace information you receive from your health care provider. You must talk with your healthcare provider for complete information about the risks and benefits of using phentermine.
Disclaimer: This information should not be used to decide whether or not to take this medicine or any other medicine. Only your health care provider has the knowledge and training to decide which medicines are right for you. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this medicine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this medicine. This information is not specific medical advice and does not replace information you receive from your health care provider. You must talk with your healthcare provider for complete information about the risks and benefits of using this medicine.
More phentermine resources
- phentermine Advanced Consumer (Micromedex) - Includes Dosage Information
- phentermine Concise Consumer Information (Cerner Multum)
- Phentermine Monograph (AHFS DI)
- Phentermine Prescribing Information (FDA)
- Adipex-P Prescribing Information (FDA)
- Ionamin Prescribing Information (FDA)
- Suprenza Prescribing Information (FDA)