Phenelzine belongs to a class of medications known as monoamine oxidase inhibitors (MAOIs). This medication is used to treat depression. Depression is caused by an imbalance of natural chemicals in the brain called neurotransmitters. Phenelzine works by inhibiting the breakdown of these chemicals in the brain, thereby restoring a balance in mood. This medication may take up to 4 weeks for full effect; however, symptoms of depression will start to improve during this period.

Your doctor may have suggested this medication for conditions other than those listed here. As well, some forms of this medication may not be used for all of the conditions discussed here. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

The recommended adult starting dose is 45 mg daily to 90 mg daily taken in 3 divided doses. Once there is a good response, the doctor will lower the dose depending on the individual. Phenelzine may be taken with or without food.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important that this medication be taken exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Phenelzine should not be taken by anyone who:

• is allergic to phenelzine or to any of the ingredients of the medication
• is taking any medications known to cause a serious drug interaction (see drug interactions for the complete list)
• has congestive heart failure
• has liver disease
• has pheochromocytoma (tumor of the adrenal glands)
• has severe kidney impairment or kidney disease
• has taken another MAOI (e.g., selegiline, tranylcypromine) in the last 14 days

People taking phenelzine must not consume foods or beverages with high tyramine content, which include:

These foods should be avoided while taking the medication and for 14 days after stopping this medication.

A side effect is an unwanted response to a medication when it is taken in normal doses. A side effect may be mild or severe, temporary or permanent, but does not occur in everyone. The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away over time. If you develop any of these side effects (or any other side effects not listed here) or they change in intensity, speak to your doctor or pharmacist for advice on managing them and on the risks and benefits of the medication.

• constipation
• dizziness
• drowsiness
• dry mouth
• excessive sleepiness
• headache
• insomnia
• lightheadedness (upon rising from sitting or lying down)
• nausea
• reduced sex drive, or impotence
• stomach upset
• swelling in the legs, ankles, or feet
• tremors or twitching
• vomiting
• weakness and fatigue
• weight gain

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Avoid certain foods and beverages: People taking this medication must not consume certain foods and beverages for 2 weeks after stopping phenelzine. Refer to the "Who should not take this medication?" section for specific examples.

Blood pressure: On rare occasions, phenelzine can cause severely high blood pressure (hypertensive crises) in some people. If you experience any of the following symptoms, contact your doctor immediately: headache at the back of the head, palpitation, neck stiffness or soreness, nausea, vomiting, sweating, fever, cold and clammy skin, dilated pupils, abnormal heart rate, or chest pain.

Diabetes: Phenelzine may affect the blood glucose (sugar) level for people with diabetes. Your doctor may want you to check your blood glucose more often while taking this medication.

Drug interactions: Phenelzine can interact with a number of different medications. Some medications need to be stopped for at least 10 to 14 days before starting phenelzine. Fluoxetine needs to be stopped at least 5 weeks before starting phenelzine. It is important to tell your doctor and pharmacists about all the prescription and over-the-counter products that you are using before taking phenelzine or other medications. Refer to the "What medications can interact with this medication?" section for specific examples.

Stopping the medication: Stopping this medication suddenly may lead to side effects. If you are thinking of stopping the medication, check with your doctor first.

Suicidal or agitated behavior: Adults and children taking this medication may feel agitated (restless, anxious, aggressive, emotional, feeling not like themselves), or they may want to hurt themselves or others. These symptoms may occur within several weeks after beginning this medication. People should be closely monitored by their doctor for emotional and behavioral changes.

Surgery: People taking phenelzine should not undergo elective surgery that requires general anesthesia.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if phenelzine passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of this medication have not been established for children.