100 Migraine Drugs, A to Z: phenelzine

Phenelzine (Nardil) is an antidepressant which was approved by the FDA for the treatment of depression in 1961. It belongs to the family of monoamine oxidase (MAO) inhibitors and it is a very effective antidepressant. However, it is rarely used because of its potential to cause side effects and serious drug and food interactions.

There have been no good trials of phenelzine for the treatment of migraines. One small study compared phenelzine with and without a beta blocker, atenolol. Atenolol is known to help migraines and lowers blood pressure, so it could prevent an increase in blood pressure from phenelzine. Phenelzine worked well with and without atenolol. Another report described 11 patients with refractory (not responding to usual drugs) migraines. Ten of the 11 patients had a greater than 50% reduction in the number of headache attacks. Two patients developed low blood pressure and one, high pressure, which was easily controlled. There was also a case report of dramatic improvement in a patient with chronic and treatment-resistant migraines.

Phenelzine can interact with other antidepressants, appetite suppressants, drugs for attention deficit disorder, some epilepsy drugs, muscle relaxants, certain blood pressure medications, some opioid (narcotic) medications, and other. Foods that can interact with phenelzine include aged cheeses, aged/dried/fermented/salted/smoked/pickled/processed meats and fish, fava beans, Italian green beans, broad beans, overripe or spoiled fruits, packaged soups, sauerkraut, red wine, and some other types of alcohol.

An adverse interaction with these drugs and foods can cause a sudden increase in blood pressure or serotonin syndrome, which can be dangerous. However, it does not mean that every drug and food listed above will always cause a serious reaction. Most people will have mild or no reaction at all and if another drug needs to be added to phenelzine, it can be started at a very low dose, and then the dose can be slowly increased.

Besides drug and food interactions, phenelzine has some unpleasant side effects of its own. These include drowsiness, dizziness, constipation, dry mouth, weight gain, sexual dysfunction, and other.

We have many other antidepressants (tricyclics and SNRIs) and other categories of drugs (CGRP drugs, Botox, epilepsy and high blood pressure medications) that are very effective for the prevention of migraines, so phenelzine is almost never used. I prescribe it only after trying many other preventive drugs but it works exceptionally well for a handful of patients for whom no other drug helps.