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Phentermine (By mouth)

Phentermine (FEN-ter-meen)

Helps you lose weight when used for a short time.

Brand Name(s):

Adipex-P, Lomaira

There may be other brand names for this medicine.

When This Medicine Should Not Be Used:

This medicine is not right for everyone. Do not use it if you had an allergic reaction to phentermine or similar medicines, or if you are pregnant.

How to Use This Medicine:

Dissolving Tablet, Capsule, Long Acting Capsule, Tablet, Dissolving Tablet

  • Your doctor will tell you how much medicine to use. Do not use more than directed.
  • This medicine is not for long-term use.
  • To avoid trouble sleeping, always take this medicine in the morning and never at bedtime or late in the evening.
    • Take the capsule 2 hours after breakfast.
    • Take the extended-release capsule before breakfast.
    • Take the disintegrating tablet in the morning, with or without food.
    • Take the phentermine tablet before breakfast or 1 to 2 hours after breakfast.
    • Take Lomaira™ tablet 30 minutes before meals.
  • Swallow the extended-release capsule whole. Do not crush, break, or chew it.
  • If you are using the disintegrating tablet, make sure your hands are dry before you handle the tablet. Place the tablet on your tongue. It should melt quickly. After the tablet has melted, swallow or take a drink of water.
  • Tablet: Swallow whole. Do not crush, break, or chew it.
  • Carefully follow your doctor's instructions about any special diet.
  • Missed dose: Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.
  • Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • Do not use this medicine and an MAO inhibitor (MAOI) within 14 days of each other.
  • Some medicines can affect how phentermine works. Tell your doctor if you are using any of the following:
    • Amphetamine medicine (including dextroamphetamine, methamphetamine)
    • Diet pills
    • Insulin or diabetes medicine
    • Medicine to treat depression (including fluoxetine, fluvoxamine, paroxetine, sertraline)
  • Do not drink alcohol while you are using this medicine.

Warnings While Using This Medicine:

  • It is not safe to take this medicine during pregnancy. It could harm an unborn baby. Tell your doctor right away if you become pregnant.
  • Tell your doctor if you are breastfeeding, or if you have kidney disease, diabetes, glaucoma, congestive heart failure, heart or blood vessel disease, high blood pressure, overactive thyroid, or a history of stroke or drug abuse. Tell your doctor if have allergies to aspirin or tartrazine.
  • This medicine may cause the following problems:
    • Primary pulmonary hypertension (a serious lung problem)
    • Heart valve disease
    • Changes in blood sugar levels
  • This medicine may make you dizzy or drowsy. Do not drive or do anything else that could be dangerous until you know how this medicine affects you.
  • This medicine can be habit-forming. Do not use more than your prescribed dose. Call your doctor if you think your medicine is not working.
  • Do not stop using this medicine suddenly. Your doctor will need to slowly decrease your dose before you stop it completely.
  • Your doctor will check your progress and the effects of this medicine at regular visits. Keep all appointments.
  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

Possible Side Effects While Using This Medicine:

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Chest pain, fainting, trouble breathing
  • Fast, slow, pounding, or uneven heartbeat
  • Seizures or tremors
  • Severe headache
  • Swelling of your feet or lower legs

If you notice these less serious side effects, talk with your doctor:

  • Changes in sex drive
  • Dizziness, drowsiness, mild headache
  • Dry mouth or a bad taste in your mouth
  • Nausea, vomiting, diarrhea, constipation, stomach cramps
  • Restlessness or nervousness, trouble sleeping

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Last Updated: 10/6/2020

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