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Phentermine Capsules or Tablets

What is this medication?

PHENTERMINE (FEN ter meen) promotes weight loss. It works by decreasing appetite. It is often used for a short period of time. Changes to diet and exercise are often combined with this medication.

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This medicine may be used for other purposes; ask your health care provider or pharmacist if you have questions.

COMMON BRAND NAME(S): Adipex-P, Atti-Plex P, Atti-Plex P Spansule, Fastin, Lomaira, Pro-Fast, Pro-Fast HS, Pro-Fast SA, Tara-8

What should I tell my care team before I take this medication?

They need to know if you have any of these conditions:

  • Agitation or nervousness
  • Diabetes
  • Glaucoma
  • Heart disease
  • High blood pressure
  • History of drug abuse or addiction
  • History of stroke
  • Kidney disease
  • Lung disease called Primary Pulmonary Hypertension (PPH)
  • Taken an MAOI like Carbex, Eldepryl, Marplan, Nardil, or Parnate in last 14 days
  • Taking stimulant medications for attention disorders, weight loss, or to stay awake
  • Thyroid disease
  • An unusual or allergic reaction to phentermine, other medications, foods, dyes, or preservatives
  • Pregnant or trying to get pregnant
  • Breast-feeding

How should I use this medication?

Take this medication by mouth with a glass of water. Follow the directions on the prescription label. Take your medication at regular intervals. Do not take it more often than directed. Do not stop taking except on your care team's advice.

Talk to your care team about the use of this medication in children. While this medication may be prescribed for children 17 years or older for selected conditions, precautions do apply.

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Overdosage: If you think you have taken too much of this medicine contact a poison control center or emergency room at once.

NOTE: This medicine is only for you. Do not share this medicine with others.

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 medication?

Do not take this medication with any of the following:

  • MAOIs like Carbex, Eldepryl, Marplan, Nardil, and Parnate

This medication may also interact with the following:

  • Alcohol
  • Certain medications for depression, anxiety, or psychotic disorders
  • Certain medications for high blood pressure
  • Linezolid
  • Medications for colds or breathing difficulties like pseudoephedrine or phenylephrine
  • Medications for diabetes
  • Sibutramine
  • Stimulant medications for attention disorders, weight loss, or to stay awake

This list may not describe all possible interactions. Give your health care provider a list of all the medicines, herbs, non-prescription drugs, or dietary supplements you use. Also tell them if you smoke, drink alcohol, or use illegal drugs. Some items may interact with your medicine.

What should I watch for while using this medication?

Visit your care team for regular checks on your progress.

Do not stop taking except on your care team's advice. You may develop a severe reaction. Your care team will tell you how much medication to take.

Do not take this medication close to bedtime. It may prevent you from sleeping.

You may get drowsy or dizzy. Do not drive, use machinery, or do anything that needs mental alertness until you know how this medication 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.

This medication may affect blood sugar levels. Ask your care team if changes in diet or medications are needed if you have diabetes.

Women should inform their care team if they wish to become pregnant or think they might be pregnant. Losing weight while pregnant is not advised and may cause harm to the unborn child. Talk to your care team for more information.

What side effects may I notice from receiving this medication?

Side effects that you should report to your care team as soon as possible:

  • Allergic reactions—skin rash, itching, hives, swelling of the face, lips, tongue, or throat
  • Heart failure—shortness of breath, swelling of the ankles, feet, or hands, sudden weight gain, unusual weakness or fatigue
  • Pulmonary hypertension—shortness of breath, chest pain, fast or irregular heartbeat, feeling faint or lightheaded, fatigue, swelling of the ankles or feet

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

  • Change in taste
  • Diarrhea
  • Dizziness
  • Dry mouth
  • Restlessness
  • Trouble sleeping

This list may not describe all possible side effects. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Where should I keep my medication?

Keep out of the reach of children. This medication can be abused. Keep your medication in a safe place to protect it from theft. Do not share this medication with anyone. Selling or giving away this medication is dangerous and against the law.

This medication may cause harm and death if it is taken by other adults, children, or pets. Return medication that has not been used to an official disposal site. Contact the DEA at 1-800-882-9539 or your city/county government to find a site. If you cannot return the medication, mix any unused medication with a substance like cat litter or coffee grounds. Then throw the medication away in a sealed container like a sealed bag or coffee can with a lid. Do not use the medication after the expiration date.

Store at room temperature between 20 and 25 degrees C (68 and 77 degrees F). Keep container tightly closed.

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NOTE: This sheet is a summary. It may not cover all possible information. If you have questions about this medicine, talk to your doctor, pharmacist, or health care provider.

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Note: Introduction and Additional Common Questions written and medically approved by Cleveland Clinic professionals.

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