MAOI Antidepressants: Their Side Effects, Uses, And MOA

Last Updated: June 10, 2020

Authored by Sharon Levy, MD, MPH

MAOI antidepressants are among the four common classes of depression medications. Browsing an MAOI antidepressants list, one will find some of the most recognizable depressive disorder medication names. However, just because they are well-known and often used does not mean that MAOI antidepressant medications are for everyone.

What Are MAOI Antidepressants?

MAOI depression medications have been in use since 1959. Standing for Monoamine Oxidase Inhibitors, these were among the most common antidepressants used. Their effects were discovered by accident when certain compounds that inhibit monoamine oxidase were used in tuberculosis patients, and euphoria was among the observed side effects of use.

These medications are effective. However, they have declined in popularity in recent years. As newer depression drug classes have developed, doctors have turned to SSRI, SNRI, and TCA antidepressants more and more. MAOI antidepressants are often not used until other classes are deemed ineffective for a given patient.

There are other examples of MAOI antidepressants used in other countries, but only the four above are approved for use within the United States.

How Do MAOI Antidepressants Work?

Understanding how MAOI antidepressants work requires understanding the function of monoamine oxidase in the body.

Monoamine oxidase is an enzyme that assists in removing norepinephrine, serotonin, and dopamine from the brain. These are all so-called “feel-good” chemicals. For individuals with depression, having these chemicals removed from the brain can leave them with levels so low that they fall into significant depressive episodes.

MAOIs inhibit the actions of the monoamine oxidase enzyme. This results in higher levels of norepinephrine, serotonin, and dopamine in the brain. As a result, someone taking these medications is then likely to feel less depressed and suffer from fewer extreme mood changes.

How long antidepressants take to work can vary. MAOIs are among the fastest-acting depression medications, with effects being felt as soon as two weeks after beginning treatment. However, full effects are generally not experienced until four to six weeks after the first dose is taken.

mood change after MAOI antidepressants

Uses Of MAOI Antidepressants

Unlike newer depression medications, MAOI antidepressants are not meant to be used to treat severe depression or bipolar disorder. Instead, they are used for mild to moderate depression. They are also used for other conditions.

Antidepressants and anxiety treatment are common, and MAOIs are no exception. They are also used to treat panic disorder and numerous phobias. Many people who suffer from PTSD also benefit from their use. They have also been used to address symptoms of Parkinson’s disease.

Sometimes patients have sexual dysfunction that is not due to depression but still related. Most antidepressants and sex drive effects are negative. However, for some, MAOIs can increase sexual desire and performance. Another concern is the way antidepressants and weight gain interact. While some MAOIs can cause weight gain, others can make it easier for patients to manage their binge eating disorder and help them lose weight.

sleepiness after MAOIs

Side Effects Of MAOI Antidepressants

The side effects of MAOI antidepressants are more significant than those caused by other classes of depression medications. They also occur more frequently and tend to leave more long-term effects of antidepressants on the brain. It is for this reason that their use has fallen out of favor. The side effects of these drugs are wide-ranging and can vary between specific medications.

Side effects of MAOI antidepressants include:

  • Dizziness on standing
  • Sleep disturbance at night
  • Sleepiness during the day
  • Blurred vision
  • Dry mouth
  • Tremor
  • Difficulty passing urine (especially in men)
  • Weight loss
  • Weight gain
  • Lower blood pressure
  • High blood pressure
  • Irregular heartbeat
  • Nausea
  • Constipation
  • Diarrhea
  • Headache
  • Insomnia
  • Skin reactions with patch administration
  • Sexual dysfunction
  • Tingling sensations

Depending on the patient, it is possible that no side effects will develop. However, most MAOI users do experience at least a few side effects. In some cases, they are significant enough to stop use.


Drug interactions can be caused by other medications, street drugs, alcohol, and even foods. In fact, MAOIs interact with foods more than most other medications. Any food containing tyramine should be limited or avoided, as this amino acid causes changes in blood pressure.

Some foods containing tyramine include:

  • Aged cheese
  • Sauerkraut
  • Cured meats
  • Draft beer
  • Soy sauce
  • Miso
  • Tofu

Chocolate is also dangerous to those taking MAOI, as is ginseng. Grapefruit and antidepressants also should not be mixed.

Many prescription and over-the-counter drugs are also dangerous when combined with MAOI antidepressants. Some medications that should be avoided or used under tight supervision include:

  • Other depression medications
  • Some pain medications, specifically phenylpiperidine derivative opioids
  • Stimulants, especially amphetamines
  • Some cold and allergy medications
  • Many herbal supplements, especially those containing ginseng and St. John’s wort
  • Tryptophan supplements
  • Tobacco
  • Glaucoma medications
  • Local and general anesthetics, especially those with epinephrine
  • Certain antibiotics

Because the potential interactions are so extensive, patients must be prepared to be their own advocates, as not all health professionals realize the extent of the dangers.

contraindications for MAOI use

Contraindications And Warnings

Even the safest MAOI antidepressants have numerous contraindications and warnings. The biggest is the risk of suicidal thoughts. MAOIs carry black box warnings about the increased risk of suicidal thoughts in patients taking them, especially those under the age of 25.

Anyone with kidney or liver impairment should avoid MAOI use. Those who have severe and uncontrolled headaches are also best to avoid these medications. Any cardiac and vascular conditions are also contraindications for their use, including high blood pressure.

Taking MAOI antidepressants while pregnant or breastfeeding is not recommended. There is a risk of harm to the child.

How To Treat MAOI Antidepressants Addiction

Addiction to MAOIs is possible, both physical, as well as psychological. It can develop either while taking medication as prescribed or purposeful increase in dosage. Whether someone is abusing their medication or just contraindicated for MAOI use, once the medicine becomes dangerous, it is time to stop. With drug rehab centers, it is possible to end dependence on MAOIs in a safe and effective manner.

Page Sources

  1. Avoiding Drug Interactions. US Food & Drug Administration. 2008.
  2. Monoamine Oxidase Inhibitor Antidepressants (MOAIs). The Australian National University. 2007.
  3. Fiedorowicz JG, Swartz KL. The role of monoamine oxidase inhibitors in current psychiatric practice. Journal of Psychiatric Practice. 2004; 10(4): 239–248.

Published on: October 15th, 2019

Updated on: June 10th, 2020

About Author

Sharon Levy, MD, MPH

After successful graduation from Boston University, MA, Sharon gained a Master’s degree in Public Health. Since then, Sharon devoted herself entirely to the medical niche. Sharon Levy is also a certified addiction recovery coach.


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