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Phentermine (By mouth)
Used as part of a diet plan to help you lose weight.
There may be other brand names for this medicine.
When This Medicine Should Not Be Used
You should not use this medicine if you have had an allergic reaction to phentermine or a bad reaction to other diet pills or amphetamines. You should not use this medicine if you have problems with drug abuse, high blood pressure, heart disease, overactive thyroid, severe anxiety or glaucoma. You should not use phentermine if you have taken an MAO inhibitor (such as Parnate®, Marplan®, or Nardil®) in the past 2 weeks.
How to Use This Medicine
Tablet, Capsule, Long Acting Capsule
- Take this medicine exactly as your doctor ordered.
- Take the tablet or capsule 1 hour before meals. To avoid trouble sleeping, take the last dose of the day about 4 to 6 hours before bedtime (unless your doctor tells you differently).
- Swallow the extended-release capsule whole. Do not break, chew, or crush. To avoid trouble sleeping, take your daily dose in the morning (unless your doctor tells you differently).
If a dose is missed:
- If you take 1 dose a day, take the missed dose as soon as possible. If you do not remember until the next day, skip the missed dose and just take your one usual dose for the day.
- If you take more than 1 dose a day, take the medicine as soon as possible. If it is almost time for your next usual dose, wait until then to take your medicine and skip the missed dose.
- You should not use two doses at the same time.
How to Store and Dispose of This Medicine
- Store at room temperature, away from heat, moisture, and direct light.
- Keep all medicine out of the reach of children.
Drugs and Foods to Avoid
Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.
- Make sure your doctor knows if you are taking amantadine, amphetamines (Dexedrine®), cocaine, pemoline (Cylert®), methylphenidate (Ritalin®), other diet pills, medicine for asthma, allergies, or colds.
- Tell your doctor if you have taken an MAO inhibitor such as Marplan® or Parnate® within the past 2 weeks.
- Avoid alcohol and caffeine while taking this medicine.
Warnings While Using This Medicine
- Check with your doctor before taking this medicine if you have Tourette's syndrome, depression, nervousness, epilepsy (seizures), kidney disease, diabetes, or a history of drug or alcohol abuse.
- Phentermine may be habit-forming. You may have withdrawal symptoms such as stomach pain, trembling, severe depression, extreme weakness or tiredness, and anxiety after you stop taking this medicine.
- If you have taken this medicine for a long time, do not suddenly stop taking it. Talk to your doctor first.
- If the medicine does not seem to work as well after a few weeks, talk to your doctor. You should not use more of it than your doctor prescribed.
- This medicine may make you dizzy or feel "high." Be careful if you are driving a car or using machinery.
- For patients with diabetes, this medicine may change the level of sugar in your blood or urine. Tell your doctor if your tests for sugar in blood or urine change.
- Talk with your doctor before use if you are pregnant or breastfeeding.
- Tell your doctor or dentist that you are taking phentermine before having any kind of surgery.
Possible Side Effects While Using This Medicine
Call your doctor right away if you notice any of these side effects:
- Fast, pounding, or irregular heartbeat
- Chest pain
- Severe headache
- Trouble breathing
- Skin rash, severe itching or hives
- Unexplained fever or sore throat
- Blurred vision, confusion, or hallucinations
- Uncontrolled body movements or seizures
If you notice these less serious side effects, talk with your doctor:
- Restlessness, trembling, or nervousness
- Changes in sex drive
- Trouble sleeping or headache
- Diarrhea or constipation
- Bad taste in the mouth or dry mouth
- Increased sweating
- Nausea, vomiting or stomach cramps
If you notice other side effects that you think are caused by this medicine, tell your doctor