Generic name: Phenelzine (FEN el zeen)
What is phenelzine and what does it treat?
Phenelzine is an antidepressant medication that works in the brain. It is approved for the treatment of major depressive disorder (MDD).
Symptoms of depression include:
- Depressed mood - feeling sad, empty, or tearful
- Feeling worthless, guilty, hopeless, and helpless
- Loss of interest or pleasure in your usual activities
- Sleep and eat more or less than usual (for most people it is less)
- Low energy, trouble concentrating, or thoughts of death (suicidal thinking)
- Psychomotor agitation (‘nervous energy’)
- Psychomotor retardation (feeling like you are moving and thinking in slow motion)
- Suicidal thoughts or behaviors
What is the most important information I should know about phenelzine?
Do not stop taking phenelzine, even when you feel better. Only your healthcare provider can determine the length of treatment that is right for you.
Missing doses of phenelzine may increase your risk for relapse in your symptoms.
Stopping phenelzine abruptly may result in one or more of the following withdrawal symptoms: irritability, nausea, dizziness, vomiting, nightmares, headache, and/or paresthesias (prickling, tingling sensation on the skin).
Depression is also a part of bipolar illness. People with bipolar disorder who take antidepressants may be at risk for "switching" from depression into mania. Symptoms of mania include "high" or irritable mood, very high self-esteem, decreased need for sleep, pressure to keep talking, racing thoughts, being easily distracted, frequently involved in activities with a large risk for bad consequences (for example, excessive buying sprees).
Medical attention should be sought if serotonin syndrome is suspected. Please refer to serious side effects for signs/symptoms.
Are there specific concerns about phenelzine and pregnancy?
If you are planning on becoming pregnant, notify your healthcare provider to best manage your medications. People living with MDD who wish to become pregnant face important decisions. Untreated MDD has risks to the fetus, as well as the mother. It is important to discuss the risks and benefits of treatment with your doctor and caregivers.
Regarding breast-feeding, caution is advised since it is not known if phenelzine passes into breast milk. Further discusses should be discussed with health care provider.
What should I discuss with my healthcare provider before taking phenelzine?
- Symptoms of your condition that bother you the most
- If you have thoughts of suicide or harming yourself
- Medications you have taken in the past for your condition, whether they were effective or caused any adverse effects
- If you experience side effects from your medications, discuss them with your provider. Some side effects may pass with time, but others may require changes in the medication.
- Any other psychiatric or medical problems you have, including a history of bipolar disorder
- All other medications you are currently taking (including over the counter products, herbal and nutritional supplements) and any medication allergies you have
- Other non-medication treatment you are receiving, such as talk therapy or substance abuse treatment. Your provider can explain how these different treatments work with the medication.
- If you are pregnant, plan to become pregnant, or are breast-feeding
- If you drink alcohol or use drugs
How should I take phenelzine?
Phenelzine is usually taken 3-4 times per day with or without food. Typically patients begin at a low dose of medicine and the dose is increased slowly over several weeks. The dose usually ranges from 15mg to 90mg. Only your healthcare provider can determine the correct dose for you.
Consider using a calendar, pillbox, alarm clock, or cell to help you remember to take your medication. You may also ask a family member or friend to remind you or check in with you to be sure you are taking your medication.
What happens if I miss a dose of phenelzine?
If you miss a dose of phenelzine take it as soon as you remember, unless it is closer to the time of your next dose. Discuss this with your healthcare provider. Do not double your next dose or take more than what is prescribed.
What should I avoid while taking phenelzine?
Avoid drinking alcohol or using illegal drugs while you are taking antidepressant medications. They may decrease the benefits (e.g., worsen your condition) and increase adverse effects (e.g., sedation) of the medication.
Special Dietary Considerations: Foods rich in tyramine and may cause a sudden and severe high blood pressure (hypertensive crisis). Avoid high protein food that has undergone protein break down via aging, fermentation, pickling, smoking, or bacterial contamination. Also avoid beverages containing tyramine. Food freshness is also important; avoid any food that may potentially be spoiled, improperly refrigerated, stored, or handled. It is important to also avoid food with excessive amounts of caffeine and/or chocolate.
Example of food to avoid include:
- Dry sausage (salami, pepperoni)
- Cheeses (aged cheeses including parmesan, aged cheddar, bleu cheese)
- Beer, wine
- Pickled herring
- Fava or broad bean pods
- Avoid foods/beverages with excessive amounts of caffeine/chocolate
These dietary considerations should be taken into consideration for 2 weeks even after phenelzine is discontinued. Discuss with health care provider any other foods or specific dietary concerns.
What happens if I overdose with phenelzine?
If an overdose occurs, call your doctor or 911. You may need urgent medical care. You may also contact the poison control center at 1-800-222-1222.
A specific treatment to reverse the effects of phenelzine does not exist.
What are the possible side effects of phenelzine?
The most common side effects of taking phenelzine are:
- Dry mouth
- Weight gain
- Decreased blood pressure (hypotension)
- Sexual dysfunction
- Blurred vision
- Urinary retention
Rare side effects:
- Elevated sodium levels
- Liver dysfunction
- Skin rash
- Hypertensive crisis; especially if low tyramine diet is not followed
- Serotonin Syndrome
Hypertensive crisis (symptoms may include occitpal headache-start in the back and radiate to the front, heart palpitations, nausea/vomiting, neck stiffness/soreness, light sensitivity, sweating)
Serotonin syndrome (symptoms may include shivering, diarrhea, confusion, severe muscle tightness, fever, seizures, and death)
Are there any risks for taking phenelzine for long periods of time?
To date, there are no known problems associated with long term use of phenelzine. It is a safe and effective medication when used as directed.
What other medications may interact with phenelzine?
Phenezline should not be taken with or within 2 weeks (6 weeks for fluoxetine) of any other mental health medications including other antidepressants (SSRIs, SNRIs, MAOIs, TCAs), mood stabilizers, antipsychotics, and antianxiety medications. Phenelzine may also interact with some pain medication, medications for migraines, amphetamines, and antibiotics. Please inform you health care providers of all your current medications and any substance use at the time of prescribing to avoid any potential side effects.
There is an increased risk of serotonin syndrome when phenezline used with other medications that increase serotonin, such as other antidepressants, migraine medications called “triptans” (e.g., Imitrex®), some pain medications (e.g., tramadol (Ultram®), amphetamines, and the antibiotic linezolid (Zyvox®).
The following medications may increase the levels and effects of phenezline: alcohol, alfuzosin, amantadine, antipsychotics, barbiturates, blood pressure lowering agents, buprenorphine, buspirone, carbamazepine, cyclobenzapine, fentanyl, ipratropium (oral inhalation), levodopa, methadone, methylene blue, oxycodone, opioid analgesics, pentoxifylline, pheniramine, phosphodiesterase 5 inhibitors (including sildenafil), tramadol, tetrabenezine, valbenazine.
The following medications may decrease the levels and effects of phenelzine: acetylcholinesterase inhibitors, amidampridine, cyprohepatdine, domperidone.
Phenezline may increase the levels and effects of: antipsychotics, atomoxetine, bupropion, cyprohepatidine, deutetrabenazine, dopamine, dextromethorphan, codeine, heroin, hydrocodone, lithium, methylphenidate, morphine, mirtazapine, MAO-Is, norepinephrine, opioid analgesics, pindolol, SSRIs, SNRIs, topiramate, tramadol, tricyclic antidepressants.
Phenezline may decrease the levels and effects of acetylcholinesterase inhibitors, gastrointestinal agents, amidapridine, domperidone, nitroglycerin.
How long does it take for phenelzine to work?
Sleep, energy, or appetite may show some improvement within the first 1-2 weeks. Improvement in these physical symptoms can be an important early signal that the medication is working. Depressed mood and lack of interest in activities may need up to 6-8 weeks to fully improve.
Summary of Black Box Warnings —
Suicidal Thoughts or Actions in Children and Adults
Depression and certain other psychiatric disorders are themselves associated with increases in the risk of suicide. Patients with major depressive disorder (MDD), both adult and pediatric, may experience worsening of their depression and/or the emergence of suicidal ideation and behavior (suicidality) or unusual changes in behavior, whether or not they are taking antidepressant medications. This risk may persist until significant remission occurs.
In short-term studies, antidepressants increased the risk of suicidality in children, adolescents, and young adults when compared to placebo. Short-term studies did not show an increase in the risk of suicidality with antidepressants compared to placebo in adults beyond age 24. Adults age 65 and older taking antidepressants have a decreased risk of suicidality. Patients, their families, and caregivers should be alert to the emergence of anxiety, restlessness, irritability, aggressiveness and insomnia. If these symptoms emerge, they should be reported to the patient’s prescriber or healthcare professional. All patients being treated with antidepressants for any indication should watch for and notify their healthcare provider for worsening symptoms, suicidality and unusual changes in behavior, especially during the first few months of treatment.
This information is being provided as a community outreach effort of the College of Psychiatric and Neurologic Pharmacists. This information is for educational and informational purposes only and is not medical advice. This information contains a summary of important points and is not an exhaustive review of information about the medication. Always seek the advice of a physician or other qualified medical professional with any questions you may have regarding medications or medical conditions. Never delay seeking professional medical advice or disregard medical professional advice as a result of any information provided herein. The College of Psychiatric and Neurologic Pharmacists disclaims any and all liability alleged as a result of the information provided herein.