MAOIs (Monoamine Oxidase Inhibitors)

MAOIs (monoamine oxidase inhibitors) are medications that help treat depression symptoms. Healthcare providers prescribe them for other conditions, as well.

MAOIs were the first type of antidepressant invented. But providers don’t often prescribe them for depression today due to several dietary issues, side effects and safety concerns. Providers typically only prescribe them if all other classes of antidepressants haven’t helped your symptoms.

What drugs are MAOIs?

MAOIs (and their brand names) that are available in the United States include:

• Isocarboxazid (Marplan®)
• Phenelzine (Nardil®)
• Selegiline (Emsam®)
• Tranylcypromine (Parnate®)

What conditions do MAOIs help treat?

Each type of MAOI has different U.S. Food and Drug Administration (FDA) approvals:

• Isocarboxazid and tranylcypromine are approved to treat major depressive disorder.
• Phenelzine is approved for treatment-resistant depression, panic disorder and social anxiety disorder.
• Selegiline is approved for major depressive disorder and additional treatment in the management of Parkinson’s disease.

Off-label uses

Healthcare providers sometimes prescribe MAOIs for other conditions. This is an off-label, or non-FDA-approved, use of the medication.

For example, providers sometimes prescribe Selegiline for ADHD.

They may prescribe tranylcypromine off-label for:

• Treatment-resistant social anxiety disorder
• Treatment-resistant panic disorder
• Atypical depression

How do MAOIs work?

MAOIs work by increasing the levels of certain neurotransmitters (chemical messengers) in your brain. This helps boost your mood and improve other depression symptoms.

More specifically, MAOIs (monoamine oxidase inhibitors) work by blocking the monoamine oxidase enzyme. This enzyme breaks down different types of neurotransmitters in your brain, including:

• Serotonin
• Norepinephrine
• Dopamine
• Tyramine

By blocking this enzyme, the medication increases the levels of these chemicals in your brain.

You can take MAOIs orally (by mouth) in tablet or capsule form. Selegiline also comes as a skin patch. Your healthcare provider will prescribe a certain dose and give you instructions for taking the medication.

What are the potential side effects of MAOIs?

Each type of MAOI has its own side effects. Be sure to talk to your healthcare provider or pharmacist about ones to look out for.

In general, common side effects of MAOIs include:

• Dizziness or lightheadedness (due to low blood pressure)
• Dry mouth
• Nausea
• Diarrhea or constipation
• Drowsiness
• Insomnia

Possible complications associated with MAOIs include:

• Risk of suicidal thoughts or behavior
• Serotonin syndrome
• Antidepressant discontinuation syndrome
• Food interactions causing high blood pressure

Suicidal thoughts or behavior

People younger than 25 years may have an increase in suicidal thoughts or behavior when taking MAOIs. This is especially the case when they first start them or change the dose.

If you or your child has suicidal thoughts or behavior, call the healthcare provider who prescribed the medication immediately. You can also dial 988 on your phone to reach the Suicide and Crisis Lifeline.

Serotonin syndrome

Serotonin syndrome is a potentially life-threatening drug reaction. It happens when you have too much serotonin in your body.

It can happen when you either take a new MAOI or take an increased dose. The syndrome most often occurs when you take an MAOI in addition to other medications that increase your serotonin levels. Examples include SSRIs and opioids.

Antidepressant discontinuation syndrome

Antidepressant discontinuation syndrome can happen if you suddenly stop taking an MAOI after taking it for at least six weeks.

Never stop taking your medication without talking to your healthcare provider first. Safely stopping antidepressants is a process. It usually takes at least four weeks to reduce your dose.

Food interactions

MAOIs prevent the breakdown of tyramine in your body, as well as in certain foods and drinks. Taking an MAOI and consuming too much tyramine causes high levels of it in your blood. This can lead to a sudden increase in blood pressure, called the tyramine pressor response.

A sudden increase in blood pressure is dangerous. In rare cases, a high tyramine level can trigger a brain bleed. This can result in death.

Which foods should I avoid on MAOIs?

Foods you should avoid while taking MAOIs include:

• Aged cheese (unaged cheeses, like cottage cheese, mozzarella and ricotta, are unlikely to have high tyramine levels unless you store them at a high temperature)
• Artisan sourdough bread
• Cured fish
• Fava beans
• Fermented beers (including tap beer)
• Fermented sausages
• Liver (fresh liver has no tyramine, but it can spoil quickly if you don’t refrigerate it, producing high levels of tyramine)
• Overripe fruits, including avocados, bananas and figs
• Salami
• Soy sauce

Tyramine can increase with the aging of food. If you take an MAOI, aim to eat fresh foods instead of leftovers.

Be sure to talk to your healthcare provider and/or a dietitian about which foods you should avoid. Your provider may ask you to check your blood pressure at home after sampling small amounts of tyramine-containing foods.

How long will it take for me to feel better?

It may take two to three weeks to notice an improvement in your symptoms after starting an MAOI. Talk to your healthcare provider if you don’t feel better after this time.

When should I call my healthcare provider?

You should have regular appointments with your healthcare provider when you’re taking an MAOI to check how well it works.

Otherwise, talk to your healthcare provider if:

• You develop bothersome side effects
• Your symptoms aren’t improving, or they’ve gotten worse
• You’re thinking of stopping the medication

Due to the potential safety concerns with MAOIs, it’s important to notify every healthcare provider you see about your use of this medication.