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What Are MAO Inhibitors?

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  • What Are MAOIs?

    What Are MAOIs?

    MAOIs (monoamine oxidase inhibitors) are a class of medications used to treat depression. They were first introduced in the 1950s as the first class of drugs designed for depression. Today, they are less popular than other medications, but some people benefit from their use.

    Follow through this slideshow to learn more about MAOIs, including how they work, who they might help, and what foods to avoid while taking them. 

  • How MAOIs Work

    How MAOIs Work

    MAOIs work with the chemicals in your brain—neurotransmitters—that allow brain cells to communicate with each other. Depression is thought to be caused by low levels of the neurotransmitters dopamine, serotonin, and norepinephrine, which collectively are called monoamines. A chemical found naturally in the body, monoamine oxidase, removes these neurotransmitters in the body.

    By inhibiting the monoamine oxidase, MAOIs allow more of the neurotransmitters to remain in the brain, thus elevating mood through improved brain cell communication.

  • More on Monoamine Oxidase

    More on Monoamine Oxidase

    Monoamine oxidase is a type of enzyme that helps neurons fire throughout the body. It is formed in the liver and cleans up neurotransmitters in the brain once they have done their jobs. 

    Besides clearing out the neurotransmitters, monoamine oxidase cleans out tyramine, a chemical that helps regulate blood pressure. MAOIs inhibit monoamine oxidase from doing its job. Unfortunately, as MAOIs are working to keep neurotransmitter levels at optimal levels, the process also adversely affects blood pressure. People taking MAOIs have to pay special attention to their blood pressure, including avoiding certain foods.

  • Dietary Restrictions with MAOIs

    Dietary Restrictions with MAOIs

    One downside to MAOIs is that there are dietary restrictions because of the elevated tyramine levels in the blood.

    When the drug was first on the market, no one knew about the tyramine and blood pressure concerns. Sadly, this caused a wave of deaths that prompted further research. Now, we know that certain foods contain excess tyramine and should be avoided.

  • Foods to Avoid While Taking an MAOI

    Foods to Avoid While Taking an MAOI

    The more food ages, the more concentrated the levels of tyramine become. This is true for aged meats, cheeses, and even leftovers in your fridge. Foods with dangerously high levels of tyramine include:

    • soy sauce and other fermented soy products
    • sauerkraut
    • salami and other aged or cured meats
  • Foods Containing Tyramine

    Foods Containing Tyramine

    Other foods that contain high levels of tyramine are:

    • aged cheeses: bleu, Brie, cheddar, Gouda, Parmesan, and Swiss
    • alcohol, especially chianti, vermouth, and beers
    • fava beans
    • raisins, dates, and other dried fruits
    • tofu
    • all nuts
  • Other Precautions

    Other Precautions

    Besides blood pressure problems, people taking MAOIs should also beware of a condition called serotonin syndrome. This is a condition with symptoms of confusion, fever, irregular or rapid heartbeat, dilated pupils, and occasional unconsciousness. The condition can manifest if a person on MAOIs takes other antidepressants, or the herbal supplement St. John’s Wort.

    To avoid serotonin syndrome, people taking MAOIs should not take anything for two weeks when ending MAOI treatment and starting another. 

  • Types of MAOIs

    Types of MAOIs

    MAOIs are rarely the first choice of prescription medication to treat depression. The Food and Drug Administration—the regulating agency of all prescription medication—has approved the following MAOIs sold under the following brand names: 

    • Isocarboxazid. Sold under the brand name Marplan, this MAOI can take 3 to 6 weeks before the full benefit is reached.
    • Phenelzine. This drug—sold as Nardil—can take up to 4 weeks to fully work.
    • Tranylcypromine. Also called Parnate, this drug can take up to 3 weeks to achieve its desired effects.
  • New MAOI: Selegiline

    New MAOI: Selegiline

    Selegiline is a newer type of MAOI. It works by selectively blocking MAO-B, which reduces the breakdown of dopamine and phenethylamine. This means there are no dietary restrictions. It is available in patch form under the brand names Atapryl, Carbex, Eldepryl, and Zelapar.

     Besides depression, selegiline is prescribed for early-onset Parkinson’s disease and dementia.

  • MAOI Side Effects

    MAOI Side Effects

    MAOIs carry more side effects than other antidepressants, which is why they are often the last drug prescribed to treat depression. Some side effects of MAOIs include:

    • fatigue
    • muscle aches
    • nervousness
    • insomnia
    • reduced libido
    • erectile dysfunction
  • More MAOI Side Effects

    More MAOI Side Effects

    Other side effects of MAOIs include:

    • dizziness
    • lightheadedness
    • diarrhea
    • dry mouth
    • high blood pressure
    • tingling of the skin
    • difficulty urinating
    • weight gain
  • MAOIs & Suicide Risk

    MAOIs & Suicide Risk

    The FDA requires a warning on antidepressants that they may increase the risk of suicide in children and young adults. While MAOIs are rarely prescribed for children, all people beginning any kind of antidepressant therapy should be watched for changes in mood, mindset, or attitude when first beginning treatment. Successful antidepressant treatments should lower suicide risk by increasing mood. However, you should consult your doctor before you stop taking MAOIs or any other prescribed medication. 

  • More Information

    More Information

    MAOIs are only one type of medication used to treat depression. Like most antidepressants, they may not be right for everyone and take weeks of use to reach their full effect. However, when used in combination with other therapies, they can be highly effective at combating depression symptoms. Talk to your doctor for more information to see if MAOI therapy suits your lifestyle.