Drugs A - Z

Phentermine Hydrochloride Oral tablet

It is used with a reduced calorie diet and exercise to help you lose weight

Generic Name: phentermine  |  Brand Name: Ionamin

What is this medicine?

PHENTERMINE (FEN ter meen) decreases your appetite. It is used with a reduced calorie diet and exercise to help you lose weight.

What should I tell my health care provider before I take this medicine?

They need to know if you have any of these conditions:
  • agitation
  • glaucoma
  • heart disease
  • high blood pressure
  • history of substance abuse
  • lung disease called Primary Pulmonary Hypertension (PPH)
  • taken an MAOI like Carbex, Eldepryl, Marplan, Nardil, or Parnate in last 14 days
  • thyroid disease
  • an unusual or allergic reaction to phentermine, other medicines, foods, dyes, or preservatives
  • pregnant or trying to get pregnant
  • breast-feeding

How should I use this medicine?

Take this medicine by mouth with a glass of water. Follow the directions on the prescription label. This medicine is usually taken 30 minutes before or 1 to 2 hours after breakfast. Avoid taking this medicine in the evening. It may interfere with sleep. Take your doses at regular intervals. Do not take your medicine more often than directed.

Talk to your pediatrician regarding the use of this medicine in children. Special care may be needed.

What if I miss a dose?

If you miss a dose, take it as soon as you can. If it is almost time for your next dose, take only that dose. Do not take double or extra doses.

What may interact with this medicine?

Do not take this medicine with any of the following medications:
  • duloxetine
  • MAOIs like Carbex, Eldepryl, Marplan, Nardil, and Parnate
  • medicines for colds or breathing difficulties like pseudoephedrine or phenylephrine
  • procarbazine
  • sibutramine
  • SSRIs like citalopram, escitalopram, fluoxetine, fluvoxamine, paroxetine, and sertraline
  • stimulants like dexmethylphenidate, methylphenidate or modafinil
  • venlafaxine

This medicine may also interact with the following medications:

  • medicines for diabetes

What should I watch for while using this medicine?

Notify your physician immediately if you become short of breath while doing your normal activities.

Do not take this medicine within 6 hours of bedtime. It can keep you from getting to sleep. Avoid drinks that contain caffeine and try to stick to a regular bedtime every night.

This medicine was intended to be used in addition to a healthy diet and exercise. The best results are achieved this way. This medicine is only indicated for short-term use. Eventually your weight loss may level out. At that point, the drug will only help you maintain your new weight. Do not increase or in any way change your dose without consulting your doctor.

You may get drowsy or dizzy. Do not drive, use machinery, or do anything that needs mental alertness until you know how this medicine affects you. Do not stand or sit up quickly, especially if you are an older patient. This reduces the risk of dizzy or fainting spells. Alcohol may increase dizziness and drowsiness. Avoid alcoholic drinks.

What side effects may I notice from receiving this medicine?

Side effects that you should report to your doctor or health care professional as soon as possible:
  • chest pain, palpitations
  • depression or severe changes in mood
  • increased blood pressure
  • irritability
  • nervousness or restlessness
  • severe dizziness
  • shortness of breath
  • problems urinating
  • unusual swelling of the legs
  • vomiting

Side effects that usually do not require medical attention (report to your doctor or health care professional if they continue or are bothersome):

  • blurred vision or other eye problems
  • changes in sexual ability or desire
  • constipation or diarrhea
  • difficulty sleeping
  • dry mouth or unpleasant taste
  • headache
  • nausea


Last Updated: February 01, 2012
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