What Is Phenelzine? Uses, Dosage, and What You Need to Know in 2026

Phenelzine — sold as Nardil — is one of the oldest antidepressants still in active use, and for many patients with hard-to-treat depression, it remains the most effective option available. Here's a plain-language overview of what phenelzine is, what conditions it treats, how to take it, and what you need to know before starting.

What Is Phenelzine?

Phenelzine is a monoamine oxidase inhibitor (MAOI). It belongs to the hydrazine class of MAOIs — one of the first groups of antidepressants ever developed, dating back to the 1950s. Despite its age, phenelzine remains one of the few non-selective, irreversible MAOIs still in widespread clinical use alongside tranylcypromine and isocarboxazid.

The brand name Nardil is made by Pfizer. Generic versions are manufactured by Lupin and Greenstone. All formulations come as a 15 mg film-coated orange tablet.

What Conditions Does Phenelzine Treat?

The FDA has approved phenelzine for:

Atypical, nonendogenous, or neurotic depression: Often featuring a mix of anxiety and depression, phobias, or hypochondria. Phenelzine is particularly effective here.

Treatment-resistant depression: When patients haven't responded to first-line antidepressants (SSRIs, SNRIs, etc.), phenelzine is often the next step.

Panic disorder: Effective in reducing the frequency and severity of panic attacks.

Social anxiety disorder: Phenelzine is FDA-approved and clinically proven to reduce social anxiety symptoms.

Off-label, phenelzine is also used for dysthymia, bipolar depression, bulimia nervosa, and post-traumatic stress disorder (PTSD). It is not FDA-approved for treating severe endogenous depression or bipolar disorder (manic depression).

How Is Phenelzine Dosed?

Phenelzine is available only as 15 mg tablets. Dosing follows this general pattern:

Starting dose: 15 mg three times daily (45 mg/day)

Target dose: At least 60 mg/day; may increase to 90 mg/day for adequate response

Response time: Many patients don't respond until they've been on 60 mg/day for at least 4 weeks

Maintenance dose: As low as 15 mg/day or every other day after maximum response is achieved

Phenelzine can be taken with or without food. If it upsets your stomach, take it with a meal.

Who Should NOT Take Phenelzine?

Phenelzine is contraindicated in patients with:

Pheochromocytoma (adrenal gland tumor)

Congestive heart failure

Severe renal impairment or renal disease

History of liver disease or abnormal liver function tests

Currently taking SSRIs, SNRIs, other MAOIs, sympathomimetics, or meperidine (within 14 days)

Is Phenelzine a Controlled Substance?

No. Phenelzine is not classified as a controlled substance by the DEA. It does not have abuse potential and is not scheduled. However, because of its complex interaction and dietary requirements, it is not a medication that should be taken casually — it requires ongoing monitoring and a committed prescriber.

The Tyramine Diet Requirement

One of the most important things to know about phenelzine is the tyramine dietary restriction. Because phenelzine blocks the enzyme that breaks down tyramine in the gut, eating high-tyramine foods can cause a dangerous spike in blood pressure (hypertensive crisis). Avoid: aged cheeses, fermented meats, tap beer, soy sauce, fava beans, and yeast extracts.

For a full guide to phenelzine's side effects, visit our post on phenelzine side effects. And if you need help finding phenelzine in stock near you, medfinder can call pharmacies and text you the results.