What is this medication for?
Phentermine belongs to the class of medications called anorexiants (appetite suppressants). It is used, along with an appropriate diet, to manage obesity for people who have not responded to an appropriate weight-reducing diet alone. This medication should only be used for a few weeks at a time, and always in combination with diet and exercise. It is thought to work by reducing the appetite of the person taking the medication, and may also have other actions on the brain and body.
Phentermine is only recommended for people with an initial body mass index (BMI) greater than or equal to 30 kg/m², or 27 kg/m² with risk factors such as diabetes, high cholesterol, or high blood pressure.
BMI is calculated with consideration to weight and height. Ask your health professional about your BMI.
Your doctor may have suggested this medication for conditions other than those listed here. As well, some forms of this medication may not be used for all of the conditions discussed here. If you are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.
Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.
What form(s) does this medication come in?
Adipex-P® is available as:
Some medications may have other generic brands available. Always ask your doctor or pharmacist about the safety of switching between brands of the same medication.
How should I use this medication?
The usual recommended daily adult dose of phentermine is one capsule or tablet (37.5 mg) taken before breakfast or 1 to 2 hours after breakfast. Some people may take one-half of the tablet (18.75 mg) once or twice daily. Your doctor may also suggest other doses.
To avoid insomnia, take this medication at least 10 to 14 hours before going to bed for the night. Do not take this medication for longer than 3 weeks unless directed by your doctor.
Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.
Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.
It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.
This medication is available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms listed here. The forms available for the specific brand you have searched are listed under "What form(s) does this medication come in?"
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Who should NOT take this medication?
Do not take phentermine if you:
- are allergic to phentermine, sympathomimetic amines (e.g., amphetamines, methylphenidate) or any of the ingredients of the medication
- are breast feeding
- are pregnant
- have advanced arteriosclerosis
- have glaucoma
- have heart disease
- have a history of drug abuse
- have moderate-to-severe high blood pressure (hypertension)
- have an overactive thyroid
- are subject to agitated states
- are taking an MAO inhibitor (e.g., phenelzine, tranylcypromine), or have taken one within the past 14 days