Some commonly used brand names are:

In the U.S.—

In Canada—

• Antidepressant -- Isocarboxazid; Phenelzine; Tranylcypromine
• Antipanic agent --Phenelzine; Tranylcypromine
• Headache, tension, prophylactic --Phenelzine; Tranylcypromine
• Vascular headache prophylactic --Phenelzine; Tranylcypromine

Monoamine oxidase (MAO) inhibitors are used to relieve certain types of mental depression. They work by blocking the action of a chemical substance known as monoamine oxidase (MAO) in the nervous system.

Although these medicines are very effective for certain patients, they may also cause some unwanted reactions if not taken in the right way. It is very important to avoid certain foods, beverages, and medicines while you are being treated with an MAO inhibitor. Your health care professional will help you obtain a list to carry in your wallet or purse as a reminder of which products you should avoid.

MAO inhibitors are available only with your doctor's prescription, in the following dosage forms:

Oral
• Isocarboxazid
  • Tablets (U.S.)
• Phenelzine
  • Tablets (U.S. and Canada)
• Tranylcypromine
  • Tablets (U.S. and Canada)

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For monoamine oxidase (MAO) inhibitors, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to any MAO inhibitor. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Diet—Dangerous reactions such as sudden high blood pressure may result when MAO inhibitors are taken with certain foods or drinks. The following foods should be avoided:

• Foods that have a high tyramine content (most common in foods that are aged or fermented to increase their flavor), such as cheeses; fava or broad bean pods; yeast or meat extracts; smoked or pickled meat, poultry, or fish; fermented sausage (bologna, pepperoni, salami, summer sausage) or other fermented meat; sauerkraut; or any overripe fruit. If a list of these foods and beverages is not given to you, ask your health care professional to provide one.
• Alcoholic beverages or alcohol-free or reduced-alcohol beer and wine.
• Large amounts of caffeine-containing food or beverages such as coffee, tea, cola, or chocolate.

Pregnancy—A limited study in pregnant women showed an increased risk of birth defects when these medicines were taken during the first 3 months of pregnancy. In animal studies, MAO inhibitors caused a slowing of growth and increased excitability in the newborn when very large doses were given to the mother during pregnancy.

Breast-feeding—Tranylcypromine passes into the breast milk; it is not known whether isocarboxazid or phenelzine passes into breast milk. Problems in nursing babies have not been reported.

Children—Studies on these medicines have been done only in adult patients, and there is no specific information comparing use of MAO inhibitors in children with use in other age groups. However, animal studies have shown that these medicines may slow growth in the young. Therefore, be sure to discuss with your doctor the use of these medicines in children.

Older adults—Dizziness or lightheadedness may be especially likely to occur in elderly patients, who are usually more sensitive than younger adults to these effects of MAO inhibitors.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking MAO inhibitors, it is especially important that your health care professional know if you are taking any of the following:

• Amphetamines or
• Antihypertensives (high blood pressure medicine) or
• Appetite suppressants (diet pills) or
• Cyclobenzaprine (e.g., Flexeril) or
• Fluoxetine (e.g., Prozac) or
• Levodopa (e.g., Dopar, Larodopa) or
• Maprotiline (e.g., Ludiomil) or
• Medicine for asthma or other breathing problems or
• Medicines for colds, sinus problems, or hay fever or other allergies (including nose drops or sprays) or
• Meperidine (e.g., Demerol) or
• Methylphenidate (e.g., Ritalin) or
• Monoamine oxidase (MAO) inhibitors, other, including furazolidone (e.g., Furoxone), procarbazine (e.g., Matulane), or selegiline (e.g., Eldepryl), or
• Paroxetine (e.g., Paxil), or
• Sertraline (e.g., Zoloft), or
• Tricyclic antidepressants (amitriptyline [e.g., Elavil], amoxapine [e.g., Asendin], clomipramine [e.g., Anafranil], desipramine [e.g., Pertofrane], doxepin [e.g., Sinequan], imipramine [e.g., Tofranil], nortriptyline [e.g., Aventyl], protriptyline [e.g., Vivactil], trimipramine [e.g., Surmontil])—Using these medicines while you are taking or within 2 weeks of taking MAO inhibitors may cause serious side effects such as sudden rise in body temperature, extremely high blood pressure, severe convulsions, and death; however, sometimes certain of these medicines may be used with MAO inhibitors under close supervision by your doctor

• Antidiabetics, oral (diabetes medicine you take by mouth) or
• Insulin—MAO inhibitors may change the amount of antidiabetic medicine you need to take

• Bupropion (e.g., Wellbutrin)—Using bupropion while you are taking or within 2 weeks of taking MAO inhibitors may cause serious side effects such as seizures

• Buspirone (e.g., BuSpar)—Use with MAO inhibitors may cause high blood pressure

• Carbamazepine (e.g., Tegretol)—Use with MAO inhibitors may increase seizures

• Central nervous system (CNS) depressants (medicines that cause drowsiness)—Using these medicines with MAO inhibitors may increase the CNS and other depressant effects

• Cocaine—Cocaine use by persons taking MAO inhibitors, including furazolidone and procarbazine, may cause a severe increase in blood pressure

• Dextromethorphan—Use with MAO inhibitors may cause excitement, high blood pressure, and fever

• Trazodone or
• Tryptophan used as a food supplement or a sleep aid—Use of these medicines by persons taking MAO inhibitors, including furazolidone and procarbazine, may cause mental confusion, excitement, shivering, trouble in breathing, or fever

• Alcohol abuse—Drinking alcohol while you are taking an MAO inhibitor may cause serious side effects

• Angina (chest pain) or
• Headaches (severe or frequent)—These conditions may interfere with warning signs of serious side effects of MAO inhibitors

• Asthma or bronchitis—Some medicines used to treat these conditions may cause serious side effects when used while you are taking an MAO inhibitor

• Diabetes mellitus (sugar diabetes)—These medicines may change the amount of insulin or oral antidiabetic medication that you need

• Epilepsy—Seizures may occur more often

• Heart or blood vessel disease or
• Liver disease or
• Mental illness (or history of) or
• Parkinson's disease or
• Recent heart attack or stroke—MAO inhibitors may make the condition worse

• High blood pressure—Condition may be affected by these medicines

• Kidney disease—Higher blood levels of MAO inhibitors may occur, which increases the chance of side effects

• Overactive thyroid or
• Pheochromocytoma (PCC)—Serious side effects may occur

Sometimes this medicine must be taken for several weeks before you begin to feel better. Your doctor should check your progress at regular visits, especially during the first few months of treatment, to make sure that this medicine is working properly and to check for unwanted effects.

Take this medicine only as directed by your doctor . Do not take more of it, do not take it more often, and do not take it for a longer time than your doctor ordered.

MAO inhibitors may be taken with or without food or on a full or empty stomach. However, if your doctor tells you to take the medicine a certain way, take it exactly as directed.

Dosing—

The dose of MAO inhibitors will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of phenelzine and tranylcypromine. If your dose is different, do not change it unless your doctor tells you to do so.

The number of tablets that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using an MAO inhibitor.

For isocarboxazid
• For oral dosage form (tablets):
  • For treatment of depression:
    • Adults—To start, 10 milligrams (mg) twice a day. Your doctor may increase your dose gradually as needed. However, the dose usually is not more than 60 mg a day.
    • Children younger than 16 years of age—Use and dose must be determined by the doctor.

For phenelzine
• For oral dosage form (tablets):
  • For treatment of depression:
    • Adults—Dose is based on your body weight. To start, the usual dose is 1 milligram (mg) per kilogram (kg) of body weight (0.45 mg per pound) a day. Your doctor may decrease or increase your dose as needed. However, the dose usually is not more than 90 mg a day.
    • Children younger than 16 years of age—Use and dose must be determined by the doctor.
    • Older adults—To start, 15 mg in the morning. Your doctor may increase your dose gradually as needed. However, the dose usually is not more than 60 mg a day.

For tranylcypromine
• For oral dosage form (tablets):
  • For treatment of depression:
    • Adults—To start, 30 milligrams (mg) a day. Your doctor may increase your dose gradually as needed. However, the dose usually is not more than 60 mg a day.
    • Children younger than 16 years of age—Use and dose must be determined by the doctor.
    • Older adults—To start, 2.5 to 5 mg a day. The doctor may increase your dose as needed. However, the dose usually is not more than 45 mg a day.

Missed dose—

If you miss a dose of this medicine, take it as soon as possible. However, if it is within 2 hours of your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.

Storage—

To store this medicine:

• Keep out of the reach of children.
• Store away from heat and direct light.
• Do not store in the bathroom, near the kitchen sink, or in other damp places. Heat or moisture may cause the medicine to break down.
• Do not keep outdated medicine or medicine no longer needed. Be sure that any discarded medicine is out of the reach of children.

When taken with certain foods, drinks, or other medicines, MAO inhibitors can cause very dangerous reactions such as sudden high blood pressure (also called hypertensive crisis). To avoid such reactions, obey the following rules of caution:

• Do not eat foods that have a high tyramine content (most common in foods that are aged or fermented to increase their flavor), such as cheeses; fava or broad bean pods; yeast or meat extracts; smoked or pickled meat, poultry, or fish; fermented sausage (bologna, pepperoni, salami, and summer sausage) or other fermented meat; sauerkraut; or any overripe fruit. If a list of these foods is not given to you, ask your health care professional to provide one.
• Do not drink alcoholic beverages or alcohol-free or reduced-alcohol beer and wine.
• Do not eat or drink large amounts of caffeine-containing food or beverages such as coffee, tea, cola, or chocolate.
• Do not take any other medicine unless approved or prescribed by your doctor. This especially includes nonprescription (over-the-counter [OTC]) medicine, such as that for colds (including nose drops or sprays), cough, asthma, hay fever, and appetite control; “keep awake'' products; or products that make you sleepy.

This medicine will add to the effects of alcohol and other CNS depressants (medicines that slow down the nervous system, possibly causing drowsiness). Some examples of CNS depressants are antihistamines or medicine for hay fever, other allergies, or colds; sedatives, tranquilizers, or sleeping medicine; prescription pain medicine or narcotics; barbiturates; medicine for seizures; muscle relaxants; or anesthetics, including some dental anesthetics. Check with your doctor before taking any of the above while you are using this medicine.

Check with your doctor or hospital emergency room immediately if severe headache, stiff neck, chest pains, fast heartbeat, or nausea and vomiting occur while you are taking this medicine. These may be symptoms of a serious side effect that should have a doctor's attention.

Do not stop taking this medicine without first checking with your doctor. Your doctor may want you to reduce gradually the amount you are using before stopping completely.

Dizziness, lightheadedness, or fainting may occur, especially when you get up from a lying or sitting position. Getting up slowly may help. When you get up from lying down, sit on the edge of the bed with your feet dangling for 1 or 2 minutes. Then stand up slowly. If the problem continues or gets worse, check with your doctor.

This medicine may cause blurred vision or make some people drowsy or less alert than they are normally. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are unable to see well or are not alert .

Before having any kind of surgery, dental treatment, or emergency treatment, tell the medical doctor or dentist in charge that you are using this medicine or have used it within the past 2 weeks. Taking MAO inhibitors together with medicines that are used during surgery or dental or emergency treatments may increase the risk of serious side effects.

Your doctor may want you to carry an identification card stating that you are using this medicine.

For patients with angina (chest pain):

• This medicine may cause you to have an unusual feeling of good health and energy. However, do not suddenly increase the amount of exercise you get without discussing it with your doctor. Too much activity could bring on an attack of angina.

For diabetic patients:

• This medicine may affect blood sugar levels. While you are using this medicine, be especially careful in testing for sugar in your blood or urine. If you have any questions about this, check with your doctor.

After you stop using this medicine, you must continue to obey the rules of caution for at least 2 weeks concerning food, drink, and other medicine, since these things may continue to react with MAO inhibitors.

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Stop taking this medicine and get emergency help immediately if any of the following side effects occur:

• Symptoms of unusually high blood pressure (hypertensive crisis)
  • Chest pain (severe);  enlarged pupils ;  fast or slow heartbeat;  headache (severe);  increased sensitivity of eyes to light;  increased sweating (possibly with fever or cold, clammy skin);  nausea and vomiting;  stiff or sore neck 
  
  

Check with your doctor as soon as possible if any of the following side effects occur:

• More common
  • Dizziness or lightheadedness (severe), especially when getting up from a lying or sitting position 
  
  

• Less common
  • Diarrhea;  fast or pounding heartbeat ;  swelling of feet or lower legs;  unusual excitement or nervousness 
  
  

• Rare
  • Dark urine;  fever;  skin rash;  slurred speech;  sore throat;  staggering walk;  yellow eyes or skin 
  
  

• Symptoms of overdose
  • Anxiety (severe);  confusion;  convulsions (seizures);  cool, clammy skin;  dizziness (severe);  drowsiness (severe);  fast and irregular pulse;  fever;  hallucinations (seeing, hearing, or feeling things that are not there);  headache (severe) ;  high or low blood pressure;  muscle stiffness;  sweating;  troubled breathing;  trouble in sleeping (severe) ;  unusual irritability 
  
  

Other side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. However, check with your doctor if any of the following side effects continue or are bothersome:

• More common
  • Blurred vision;  decreased amount of urine;  decreased sexual ability;  dizziness or lightheadedness (mild), especially when getting up from a lying or sitting position;  drowsiness;  headache (mild);  increased appetite (especially for sweets) or weight gain;  increased sweating;  muscle twitching during sleep;  nausea ;  restlessness;  shakiness or trembling;  tiredness and weakness;  trouble in sleeping 
  
  

• Less common or rare
  • Chills;  constipation;  decreased appetite;  dryness of mouth 
  
  

Other side effects not listed above may also occur in some patients. If you notice any other effects, check with your doctor.

Once a medicine has been approved for marketing for a certain use, experience may show that it is also useful for other medical problems. Although these uses are not included in product labeling, phenelzine and tranylcypromine are used in certain patients with the following medical conditions:

• Headache
• Panic disorder

Other than the above information, there is no additional information relating to proper use, precautions, or side effects for these uses.