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Phenelzine (By mouth)

Phenelzine (FEN-el-zeen)

Treats depression. This medicine is a monoamine oxidase inhibitor (MAOI).

Brand Name(s):


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 phenelzine, or if you have high blood pressure, liver disease, heart disease, cerebrovascular disease, kidney disease, frequent headaches, or pheochromocytoma (a tumor of the adrenal gland). Make sure your doctor knows about all medicines you are taking, because this drug interacts with many other medicines.

How to Use This Medicine:


  • Take your medicine as directed. Your dose may need to be changed several times to find what works best for you. It may take 4 weeks of using this medicine before you start to feel better.
  • This medicine should come with a Medication Guide. Ask your pharmacist for a copy if you do not have one.
  • 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.

  • Tell your doctor about all other medicines you are using. MAO inhibitors can be very dangerous if used with other medicines. You may need to wait 1 to 5 weeks after stopping this medicine before you start using another medicine. Tell your doctor if you are using any of the following:
    • Any other medicine to treat depression
    • Diuretics or other blood pressure medicines
    • Medicine that makes you sleepy, such as allergy medicine or narcotic pain medicine
  • Do not drink alcohol while you are using this medicine.
  • Do not drink large amounts of caffeine while you are using this medicine.
  • Aged, smoked, and fermented foods can cause dangerously high blood pressure in people who are using an MAO inhibitor. Avoid the following foods and drinks:
    • Aged cheese
    • Canned figs and dried fruits
    • Caviar and liver
    • Sauerkraut
    • Smoked or pickled meat, such as smoked sausage, anchovies, or herring
    • Sour cream, yogurt, and yeast
    • Soy sauce

Warnings While Using This Medicine:

  • Tell your doctor if you are pregnant or breastfeeding, or if you have Parkinson disease, angina (chest pain), kidney disease, diabetes, or epilepsy. Your doctor also needs to know if you have schizophrenia, an overactive thyroid, or a history of drug or alcohol addiction.
  • For some teenagers and young adults, this medicine can increase thoughts of suicide. Tell your doctor right away if you start to feel more depressed or have thoughts about hurting yourself. Tell your doctor if you or anyone in your family has bipolar disorder (manic depression) or has tried to commit suicide.
  • This medicine may raise your blood pressure.
  • 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.
  • Tell any doctor or dentist who treats you that you are using this medicine. You may need to stop using this medicine several days before you have surgery or medical tests.
  • Do not stop using this medicine suddenly. Your doctor will need to slowly decrease your dose before you stop it completely.
  • 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
  • Changes in behavior, thoughts of hurting yourself or others
  • Dark urine or pale stools, nausea, vomiting, stomach pain, loss of appetite, yellow skin or eyes
  • Fast, slow, or pounding heartbeat
  • Feeling nervous, restless, anxious, agitated, or excited for no reason
  • Frequent headaches
  • Lightheadedness or dizziness
  • Seizures, tremors, or muscle twitching
  • Sensitivity to light, unusual sweating (sometimes with fever or cold, clammy skin)
  • Severe headache, stiff or sore neck, tightness in your throat or chest

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

  • Dry mouth
  • Mild diarrhea, constipation, or stomach pain

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: 11/4/2014
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