Phenelzine | Side Effects, Dosage, Uses & More
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Generic Name:

phenelzine, Oral tablet

All Brands

  • Nardil
SECTION 1 of 5

Highlights for phenelzine

Oral tablet
1

Phenelzine is used to treat depression.

2

This drug comes in the form of a tablet that you take by mouth.

3

Phenelzine is available as the brand-name drug called Nardil. It’s also available as a generic drug.

4

The more common side effects of this drug include dizziness, headache, drowsiness, trouble sleeping, tiredness, and weakness.

5

In some cases, phenelzine can cause serious side effects. These include a high blood pressure, low blood pressure, or suicidal thoughts or actions (thoughts or behaviors of harming yourself) in children, teenagers, or young adults.

IMPORTANT INFORMATION

FDA warning

This drug has a black box warning. This is the most serious warning from the Food and Drug Administration (FDA). A black box warning alerts doctors and patients about drug effects that may be dangerous. 

Suicidal thoughts warning. Drugs used to treat depression, including this drug, may cause an increase in suicidal thoughts or actions (thoughts or behaviors of harming yourself). This risk is higher in children, teenagers, or young adults, and within the first few months of treatment or during dose changes. If you have a family history of bipolar disorder, you may also have a higher risk. 

You and your family members, caregivers, and doctor should watch for any new or sudden changes in your mood, behaviors, thoughts, or feelings. Call your doctor right away if you have any of these changes.

Very high blood pressure

This drug can cause very high blood pressure. This can lead to bleeding in your brain and may even be fatal (cause death). Symptoms include headache, fast or slow heart rate, chest pain, neck stiffness or soreness, nausea, and vomiting. They also include large pupils, sensitivity to light, and sweating with a fever or cold, clammy skin. Call your doctor right away if you have a fast heart rate or a very bad headache.

Elective surgery

Don’t have any elective surgeries that require you to have general anesthesia while you’re taking this drug. This can cause low blood pressure. You should stop taking this drug at least 10 days before having an elective surgery.

Low blood pressure

This drug may cause low blood pressure. This is most likely when you stand up quickly from a sitting or lying position. If this happens, your doctor may lower your dose or have you stop taking this drug.

Drug features

This drug is a prescription drug. It’s available as an oral tablet. 

This drug is available as a generic drug. Generic drugs usually cost less. In some cases, they may not be available in every strength or form as the brand-name version.

This medication may be used as part of a combination therapy. This means you may need to take it with other medications.

Why it's used

This drug is used to treat depression. It’s often given to people with mixed anxiety and depression. This medication is normally used in people who haven’t responded to other depression drugs.

How it works

This drug belongs to a class of drugs called monoamine oxidase inhibitors. A class of drugs is a group of medications that work in a similar way.

More Details

How it works

This drug belongs to a class of drugs called monoamine oxidase inhibitors. A class of drugs is a group of medications that work in a similar way. These drugs are often used to treat similar conditions. 

This drug blocks the monoamine oxidase enzyme. This is a protein in your body that has many different actions. Drugs that block this enzyme have many effects. However, it’s not exactly known how this drug works to treat depression.

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phenelzine Side Effects

Oral tablet

More Common Side Effects

The more common side effects of phenelzine can include:

  • dizziness

  • headache

  • drowsiness

  • trouble sleeping

  • tiredness

  • weakness

  • tremors (shakiness)

  • twitching

  • jerking movements

  • strong reflexes

  • constipation

  • dry mouth

  • upset stomach

  • weight gain

  • dizziness after you stand up due to low blood pressure

  • swelling of your feet or legs

  • not being able to perform sexually as well as normal

If these effects are mild, they may go away within a few days or a couple of weeks. If they’re more severe or don’t go away, talk to your doctor or pharmacist.

Serious Side Effects

Call your doctor right away if you have serious side effects. Call 9-1-1 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include the following:

  • Suicidal thoughts or actions. Symptoms include:

    • attempts to commit suicide (harm yourself)
    • acting on dangerous impulses
    • acting aggressive or violent
    • thoughts about suicide or dying
    • new or worse depression
    • new or worse anxiety or panic attacks
    • feeling agitated, restless, angry, or irritable
    • trouble sleeping
  • High blood pressure crisis. Symptoms include:

    • severe headache
    • fast or slow heart rate
    • chest pain
    • neck stiffness or soreness
    • nausea or vomiting
    • sweating with a fever or cold, clammy skin
    • large pupils
    • sensitivity to light
  • Mania. Symptoms include:

    • greatly increased energy
    • severe trouble sleeping
    • racing thoughts
    • reckless behavior
    • unusually grand ideas
    • excessive happiness or irritability
    • talking more or faster than usual
Pharmacist's Advice
Healthline Pharmacist Editorial Team

This drug may cause drowsiness.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this information includes all possible side effects. This information is not a substitute for medical advice. Always discuss possible side effects with a healthcare provider who knows your medical history.
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phenelzine May Interact with Other Medications

Oral tablet

Phenelzine can interact with other medications, vitamins, or herbs you may be taking. An interaction is when a substance changes the way a drug works. This can be harmful or prevent the drug from working well.

To help avoid interactions, your doctor should manage all of your medications carefully. Be sure to tell your doctor about all medications, vitamins, or herbs you’re taking. To find out how this drug might interact with something else you’re taking, talk to your doctor or pharmacist.

Food interactions

Eating certain foods that contain tyramine or dopamine with this drug may increase your risk of severe, uncontrolled high blood pressure. You shouldn’t consume the following foods or beverages while taking phenelzine and for 2 weeks after stopping the drug: 

  • liver
  • dry sausage, including Genoa salami, hard salami, pepperoni, and Lebanon bologna
  • broad bean or fava bean pods
  • sauerkraut
  • cheese. (You can eat cottage cheese and cream cheese.)
  • yogurt
  • beer and wine (including alcohol-free or reduced-alcohol products)
  • yeast extract
  • meat extract
  • large amounts of chocolate or caffeine. You should limit caffeine to two 8-oz servings per day. Limit chocolate to 16 oz. per day.
  • meats, fish, and dairy products that may be spoiled or were improperly refrigerated, handled, or stored
  • aged, pickled, fermented, or smoked foods

Alcohol interaction

You shouldn’t consume any drinks that contain alcohol (beer or wine, including alcohol-free or reduced-alcohol products) while taking phenelzine or for 2 weeks after stopping this drug. Beer and wine contain tyramine. This can increase your risk of developing severe, uncontrolled high blood pressure. Other forms of alcohol can lead to increased drowsiness and sedation from this drug.

Medications that might interact with this drug

Drugs you shouldn’t take

Taking certain drugs with phenelzine may cause serious side effects. You shouldn’t take these medications together. These drugs include:

  • Stimulant-type drugs, such as amphetamines, methylphenidate, dopamine, epinephrine, norepinephrine, or methyldopa. Taking these drugs with phenelzine can increase your risk for high blood pressure.
  • Central nervous system (CNS) depressants, such as dextromethorphan or narcotic pain drugs. Taking these drugs with phenelzine can increase your risk for drowsiness and sedation. Taking dextromethorphan with phenelzine may also cause a coma (being unconscious for a long time), fever, and low blood pressure that could be fatal (cause death).
  • Other monoamine oxidase inhibitors (MAOIs), such as procarbazine and tranylcypromine. MAOIs can cause a high blood pressure crisis when they’re used together. Taking these drugs together can also cause seizures, fever, sweating, excitation, delirium, tremor, coma (being unconscious for a long time), or a heart attack. You should wait at least 14 days after stopping one MAOI before starting another one.
  • Meperidine. A single dose of meperidine can cause severe reactions when taken with phenelzine. These include excitation, seizures, delirium, fever, coma (being unconscious for a long time), a heart attack, and death.
  • Buspirone. Taking buspirone with phenelzine can cause high blood pressure. You should wait at least 14 days after stopping phenelzine before starting buspirone or vice versa.
  • Drugs that increase the levels of serotonin in your body, such as fluoxetine, paroxetine, sertraline, citalopram, or venlafaxine. Taking phenelzine with drugs that increase serotonin can cause serious reactions. These include fever, stiff muscles, strange body movements, or death. You should wait at least 14 days after stopping phenelzine before starting a serotonin reuptake inhibitor drug (except fluoxetine) or vice versa. You should wait at least 5 weeks after stopping fluoxetine before starting phenelzine or vice versa.
  • Bupropion. You should wait at least 14 days after stopping phenelzine before starting bupropion or vice versa.
  • Over-the-counter or prescription cough, cold, hay fever (allergy), sinus, asthma, weight loss, or nasal decongestant medications. Taking these drugs with phenelzine can cause headaches and other serious symptoms due to a rise in blood pressure. 

Drugs that cause more side effects

Taking phenelzine with certain drugs may cause more side effects. These drugs include:

  • Other antidepressants, such as amitriptyline, desipramine, doxepin, mirtazapine, carbamazepine, and cyclobenzaprine. These drugs can increase the side effects of phenelzine when they’re taken together or within 10 days of stopping either drug.
  • Blood pressure drugs, such as benazepril, losartan, acebutolol, amlodipine, or diuretics. Taking phenelzine with drugs that lower blood pressure can increase your risk for low blood pressure.
  • Barbiturates, such as phenobarbital. Taking these drugs together may increase drowsiness. Your doctor may give you a lower dose of your barbiturate if you need to take these drugs together.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs interact differently in each person, we cannot guarantee that this information includes all possible interactions. This information is not a substitute for medical advice. Always speak with your healthcare provider about possible interactions with all prescription drugs, vitamins, herbs and supplements, and over-the-counter drugs that you are taking.

People with pheochromocytoma

This drug can cause very high blood pressure. You shouldn’t take this drug if you have this condition since you’re already at risk for high blood pressure.

People with heart failure

This drug can cause very high blood pressure. You shouldn’t use this drug if you have heart failure since very high blood pressure can make your heart failure worse.

People with kidney problems

If you have kidney problems or a history of kidney disease, you may not be able to clear this drug from your body. This may increase the levels of this drug in your body and cause more side effects. People with severe kidney problems shouldn’t take this drug.

People with liver problems

If you have liver problems or a history of liver disease, you may not be able to process this drug well. This may increase the levels of this drug in your body and cause more side effects. People with a history of liver disease or abnormal liver function test results shouldn’t take this drug.

People with a history of seizures

This drug can have unpredictable effects on seizures. It may make your seizures either more or less likely. If you have a history of seizures, ask your doctor whether this drug is safe for you.

People with schizophrenia

This drug can cause excessive stimulation in people with schizophrenia. This may make it more difficult to control your condition.

People with a history of mania

A common side effect of this drug is agitation and excitement. This may lead to mania in people with a history of mania or who are at risk for mania. Your risk may be higher if you use this drug at high doses or for a long time.

People with diabetes

This drug may increase your sensitivity to insulin. Your doctor may need to change the doses of your diabetes medications.

Pregnant women

The Food and Drug Administration (FDA) hasn’t assigned a pregnancy category to this drug. It is not known if this drug is safe and effective for use in pregnant women.

Tell your doctor if you’re pregnant or plan to become pregnant. This drug should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.

Women who are breast-feeding

This drug may pass into breast milk and may cause side effects in a child who is breast-fed. 

Talk to your doctor if you breast-feed your child. You may need to decide whether to stop breast-feeding or stop taking this medication.

For seniors

The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This raises your risk of side effects.

For children

It hasn’t been confirmed if this drug is safe and effective for use in people younger than 18 years. This drug shouldn’t be used in children younger than 18 years.

When to call the doctor

Call your doctor right away if you become pregnant while taking this drug.

Call your doctor if your depression symptoms don’t get better, or if they get worse. Note that many people don’t respond to this drug until they’ve been taking 60 mg per day for at least 4 weeks.

Allergies

This drug can cause a severe allergic reaction. Symptoms can include: 

  • trouble breathing
  • swelling of your throat or tongue 

If you have an allergic reaction, call your doctor or local poison control center right away. If your symptoms are severe, call 9-1-1 or go to the nearest emergency room. 

Don’t take this drug again if you’ve ever had an allergic reaction to it. Taking it again could be fatal (cause death).

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How to Take phenelzine (Dosage)

Oral tablet

All possible dosages and drug forms may not be included here. Your dosage, drug form, and how often you take the drug will depend on: 

  • your age
  • the condition being treated
  • how severe your condition is
  • other medical conditions you have
  • how you react to the first dose

What are you taking this medication for?

Depression

Generic: phenelzine

Form: Oral tablet
Strength: 15 mg

Brand: Nardil

Form: Oral tablet
Strength: 15 mg
Adult dosage (ages 18–64 years)
  • Typical starting dose: 15 mg taken three times per day
  • Dose increases: Your doctor may increase your dose to 60 mg per day as quickly as you can tolerate it. Your dose may need to be increased to 90 mg per day. After the maximum benefit of this drug is achieved, your doctor will reduce your dose slowly over several weeks. Your maintenance dose may be as low as 15 mg per day or 15 mg taken every other day.
Child dosage (ages 0–17 years)

It hasn’t been confirmed that this drug is safe and effective for use in people younger than 18 years of age.

Senior dosage (ages 65 years and older)

The kidneys of older adults may not work as well as they used to. This can cause your body to process drugs more slowly. As a result, more of a drug stays in your body for a longer time. This raises your risk of side effects.

Your doctor may start you on a lower dose or a different dosing schedule. This can help keep levels of this drug from building up too much in your body.

Warnings

Don’t stop this drug without talking to your doctor. Stopping this drug too quickly can cause withdrawal symptoms.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this list includes all possible dosages. This information is not a substitute for medical advice. Always to speak with your doctor or pharmacist about dosages that are right for you.
Pharmacist's Advice
Healthline Pharmacist Editorial Team

This drug comes with serious risks if you don’t take it as prescribed.

If you stop taking the drug suddenly or don’t take it at all

Stopping this drug quickly can cause withdrawal symptoms. These include nausea, vomiting, or muscle aches. In rare cases, this drug may cause agitation, nightmares, psychosis, and convulsions (violent, involuntary movements) within 24–72 hours of stopping this drug. Call your doctor if this happens. If you need to stop taking this drug, your doctor will slowly lower your dose over time.

If you don’t take this drug at all, your depression won’t get better. It may even get worse.

If you miss doses or don’t take the drug on schedule

Your medication may not work as well or may stop working completely. For this drug to work well, a certain amount needs to be in your body at all times.

If you take too much

You could have dangerous levels of the drug in your body. Symptoms of an overdose of this drug can include:

  • drowsiness
  • dizziness
  • faintness
  • irritability
  • hyperactivity
  • agitation
  • severe headache
  • hallucinations (seeing or hearing something that isn’t there)
  • stiff muscles, including your jaw, head, neck, or back
  • convulsions (violent, involuntary movements)
  • coma (being unconscious for a long time)
  • fast or irregular heart rate
  • high or low blood pressure
  • breathing problems
  • fever
  • sweating
  • cool, clammy skin

If you think you’ve taken too much of this drug, call your doctor or local poison control center. If your symptoms are severe, call 9-1-1 or go to the nearest emergency room right away.

What to do if you miss a dose

Take your dose as soon as you remember. But if you remember just a few hours before your next scheduled dose, take only one dose. Never try to catch up by taking two doses at once. This could result in dangerous side effects.

How to tell if the drug is working

Your depression symptoms will be less severe or may happen less often.

Many people don’t respond to this drug until they’ve been taking a dose of 60 mg per day for at least 4 weeks.

This drug is used for long-term treatment.

Important considerations for taking this drug
take this drug with or without food You can take this drug with or without food
timing Take this drug at the time(s) recommended by your doctor
can cut or crush the tablet You can cut or crush the tablet
storage Store this drug carefully See Details
medication is refillable A prescription for this medication is refillable See Details
Travel Travel See Details
Clinical monitoring Clinical monitoring See Details
diet Your diet See Details
not usually stocked Not every pharmacy stocks this drug. When filling your prescription, be sure to call ahead
prior authorization Insurance See Details

Store this drug carefully

  • Store this drug at room temperature. Keep it between 59°F and 86°F (15°C and 30°C). Keep it away from light.
  • Don’t store this medication in moist or damp areas, such as bathrooms.

A prescription for this medication is refillable

You should not need a new prescription for this medication to be refilled. Your doctor will write the number of refills authorized on your prescription.

Travel

When traveling with your medication:

  • Always carry your medication with you. When flying, never put it into a checked bag. Keep it in your carry-on bag.
  • Don’t worry about airport x-ray machines. They can’t hurt your medication.
  • You may need to show airport staff the pharmacy label for your medication. Always carry the original prescription-labeled box with you.
  • Don’t put this medication in your car’s glove compartment or leave it in the car. Be sure to avoid doing this when the weather is very hot or very cold.

Clinical monitoring

You and your doctor should monitor certain health issues. This can help make sure you stay safe while you take this drug. These issues include: 

  • Mental health and depression. Your doctor will monitor your symptoms of depression to make sure that this drug is working. Pay close attention to sudden changes in your mood, behaviors, thoughts, or feelings, especially when starting this drug or during dose changes. Call your doctor right away if you have any unusual changes.
  • Blood pressure. Your doctor will monitor your blood pressure to make sure that it’s not too high or low.

Your diet

Eating certain foods that contain tyramine or dopamine with this drug may increase your risk of developing severe uncontrolled blood pressure. You shouldn’t consume the following foods or beverages while taking this drug and for 2 weeks after stopping the drug:

  • liver
  • dry sausage, including Genoa salami, hard salami, pepperoni, and Lebanon bologna
  • broad bean or fava bean pods
  • sauerkraut
  • cheese (You can eat cottage cheese and cream cheese.)
  • yogurt
  • beer and wine (including alcohol-free or reduced-alcohol products)
  • yeast extract
  • meat extract
  • large amounts of chocolate or caffeine. You should limit caffeine to two 8-oz servings per day. Limit chocolate to 16 oz per day.
  • meats, fish, and dairy products that may be spoiled or were improperly refrigerated, handled, or stored
  • aged, pickled, fermented, or smoked foods

Insurance

Many insurance companies require a prior authorization for this drug. This means your doctor will need to get approval from your insurance company before your insurance company will pay for the prescription.

Are there any alternatives?

There are other drugs available to treat your condition. Some may be better suited for you than others. Talk to your doctor about other drug options that may work for you.

What does the pill look like?

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How Much Does phenelzine Cost?

Oral tablet

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Lowest price for phenelzine

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These prices represent the lowest priced national pharmacies for phenelzine on GoodRx. They may be lower than your insurance.

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These prices represent the lowest priced national pharmacies for phenelzine on GoodRx. They may be lower than your insurance.

Show Sources

Content developed in collaboration with University of Illinois-Chicago, Drug Information Group

Medically reviewed by Creighton University, Center for Drug Information and Evidence-Based Practice on November 30, 2015

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up-to-date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.
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