Phenelzine is an antidepressant (monoamine oxidase inhibitor). This medication treats depression by restoring the balance of certain natural substances (neurotransmitters) in the brain. Phenelzine can improve your mood and feelings of well-being. Usually, this medication is used in persons who have not responded to treatment with other drugs.
This drug should not be used with the following medications because very serious (possibly fatal) interactions may occur: other antidepressants (including maprotiline, mirtazapine, nefazodone, SNRIs such as duloxetine/venlafaxine, SSRIs such as citalopram/fluoxetine/paroxetine, TCAs such as amitriptyline/nortriptyline), appetite suppressants (e.g., diethylpropion), drugs for attention deficit disorder (e.g., atomoxetine, methylphenidate), certain antihistamines (azatadine, carbetapentane, chlorpheniramine), apraclonidine, bupropion, buspirone, carbamazepine, cyclobenzaprine, dextromethorphan, certain drugs for high blood pressure (e.g., guanethidine, methyldopa), other MAO inhibitors (isocarboxazid, linezolid, methylene blue, moclobemide, procarbazine, rasagiline, selegiline, tranylcypromine), certain narcotic medications (such as fentanyl, meperidine, methadone, tapentadol), certain drugs for Parkinson's (e.g., entacapone, levodopa, tolcapone), street drugs (e.g., MDMA/"ecstasy", LSD, mescaline), stimulants (e.g., amphetamines, cocaine, dopamine, epinephrine, phenylalanine), tetrabenazine, "triptan" migraine drugs (e.g., sumatriptan, rizatriptan), tramadol, tyrosine, tryptophan.
If you are currently using any of these medications listed above, tell your doctor or pharmacist before starting phenelzine. Do not take these medications within the 2 weeks before, during or after treatment with phenelzine. If you have been taking fluoxetine, wait at least 5 weeks after stopping fluoxetine before starting phenelzine. Discuss with your doctor how much time to wait between starting or stopping any of these drugs and taking phenelzine.
Before using this medication, tell your doctor or pharmacist of all prescription and nonprescription/herbal products you may use, especially of: drugs for high blood pressure (e.g., beta blockers such as atenolol, clonidine, rauwolfia alkaloids such as reserpine, "water pills"/diuretics such as hydrochlorothiazide).
Also report the use of drugs which might increase seizure risk (decrease seizure threshold) when combined with phenelzine such as isoniazid (INH), phenothiazines (e.g., thioridazine), theophylline, or tricyclic antidepressants (e.g., imipramine) among others. Consult your doctor or pharmacist for details.
Tell your doctor or pharmacist if you also take drugs that cause drowsiness such as: certain antihistamines (e.g., diphenhydramine), anti-seizure drugs (e.g., phenytoin), medicine for sleep or anxiety (e.g., alprazolam, diazepam, zolpidem), muscle relaxants, narcotic pain relievers (e.g., codeine), psychiatric medicines (e.g., chlorpromazine, lithium, risperidone, trazodone).
Check the labels on all your medicines (e.g., allergy, cough-and-cold products, decongestants, diet pills) because they may contain dextromethorphan, decongestants, stimulants, or drowsiness-causing ingredients. Ask your pharmacist about the safe use of those products.
Common side effects of Phenelzine include:
- Problems sleeping
- Dry mouth
If any of these effects persist or worsen, notify your doctor or pharmacist promptly.
Tell your doctor immediately if any of these unlikely but serious side effects occur: fainting, mental/mood changes (e.g., agitation, confusion), muscle stiffness/twitching, changes in sexual ability/interest, shaking (tremor), shivering, swollen ankles/legs, unusual weight gain, vision changes (e.g., double/blurred vision).
Tell your doctor immediately if any of these highly unlikely but very serious side effects occur: severe stomach/abdominal pain, persistent nausea/vomiting, seizures, dark urine, yellowing eyes/skin.
This drug may rarely cause an attack of extremely high blood pressure (hypertensive crisis), which may be fatal. Many drug and food interactions can increase this risk (See also Drug Interaction section.) Stop taking phenelzine and seek immediate medical attention if any of these serious side effects occur: frequent/severe headache, fast/slow/irregular/pounding heartbeat, chest pain, neck stiffness/soreness, severe nausea/vomiting, sweating/clammy skin (sometimes with fever), widened pupils, sudden sensitivity to light (photophobia).
Special Dietary Caution:
It is very important that you follow special dietary restrictions in order to limit the amount of tyramine in your diet. Avoid drinking large amounts of beverages containing caffeine (coffee, tea, colas) or eating large amounts of chocolate. Caffeine can increase the side effects of this medication. Foods and beverages high in tyramine should be avoided while you are taking this medication and for at least 2 weeks after you stop using this medication.
Foods high in tyramine include: aged cheeses (cheddar, camembert, emmenthaler, brie, stilton blue, gruyere, gouda, brick, bleu, roquefort, boursault, parmesan, romano, provolone, liederdranz, colby, edam), aged/dried/fermented/salted/smoked/pickled/processed meats and fish (includes bacon, summer sausage, liverwurst, hot dogs, corned beef, pepperoni, salami, bologna, ham, mortadella, pickled or dried herring), banana peel, beef/chicken liver (stored, not fresh), bouillon cubes, commercial gravies, concentrated yeast extracts, fava beans, Italian green beans, broad beans, fermented bean curd, homemade yeast-leavened bread, kim chee (Korean fermented cabbage), orange pulp, overripe or spoiled fruits, packaged soups, red wine, sauerkraut, sherry, snow pea pods, sourdough bread, soy sauce, soybeans, soybean paste/miso, tofu, tap beer and ale, vermouth.
Moderate-to-low tyramine content foods include: alcohol-free beer, avocados, bananas, bottled beer and ale, chocolate and products made with chocolate, coffee, cola, cultured dairy products (e.g. buttermilk, yogurt, sour cream), distilled spirits, eggplant, canned figs, fish roe (caviar), green bean pods, pate, peanuts, port wine, raisins, raspberries, red plums, spinach, tomatoes, white wine.
Tell your doctor or pharmacist immediately if you notice symptoms of high blood pressure such as fast/slow heartbeat, vomiting, sweating, headache, chest pain, sudden vision changes, weakness on one side of the body, or slurred speech.