Monoamine Oxidase Inhibitors (MAOIs), like most other antidepressants, work by targeting and, to some degree, preventing changes in brain chemistry that result in a depressed mood. Although MAOIs have, for the most part, been replaced by newer generations of antidepressant medications, they are still in use because they are particularly effective for treating some major and treatment-resistant forms of depression.

In fact, because they are so effective, some mental health experts are calling for wider consideration of MAOIs for difficult-to-treat depressive conditions, and for more training of new physicians on how to use them. MAOIs currently approved for treating depression include oral phenelzine (brand name Nardil), tranylcypromine (Parnate), and isocaroxazid (Marplan), and the transdermal patch form of selegiline (EMSAM).1,2

“When researchers looked at how MAOIs were being used in the 1980s, they were commonly being prescribed for people with bipolar disorder,” recalls psychiatrist Matthew Edlund, MD, MOH, director of the Center for Circadian Medicine in Sarasota, Florida. “They worked particularly well for older adults.”

But back in the 1950s, when MAOI medications were first introduced and prescribed to treat depression, patients began having problems with high blood pressure and migraine headaches, especially after eating specific types of foods. Medical experts took note, and researchers determined that a dangerous and potentially fatal interaction was occurring when these patients ate foods rich in tyramine, an amino acid (protein) found in the diet and also naturally produced in the body.3 Foods rich in tyramine include aged, cured, pickled, smoked and fermented foods, tap or unpasteurized beer, red wine, dried fruit, and fresh citrus.

How MAOIs Work

While they are in your body, MAOI medications inhibit, or block, the action of an enzyme known as monoamine oxidase. One of the usual jobs this enzyme performs is to remove certain neurotransmitters (chemical messengers such as serotonin, norepinephrine and dopamine) from your brain, in order to maintain a normal flow. MAOIs prevent this removal, allowing these “feel good” chemicals to flood those areas of your brain that are involved in depression and help elevate your mood.

At the same time, however, MAOIs also prevent this enzyme from doing another one of its usual jobs, which is to metabolize, or break down, tyramine to a form that is easily eliminated from your body. This normal process of elimination also prevents tyramine from building up to unsafe levels in your body, whether it occurs naturally or comes from your diet.

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So while you are taking MAOIs for depression, Dr. Edlund explains, your body is already working harder to process naturally occurring tyramine. Any tyramine that comes from your diet is “extra,” and can easily accumulate in your body and overload the system. That’s what causes side effects such as headaches and elevated blood pressure, as well as gastrointestinal upset, rapid heartbeat, shortness in breath, and neurological problems like confusion, anxiety, and vision changes that accompany sudden surges in blood pressure. When blood pressure shoots up high enough, there is the possibility of a hypertensive crisis, which can be deadly.

Avoiding Dangerous Side Effects

The way to prevent these side effects is to avoid eating foods that are high in tyramine throughout the period of time you are taking MAOIs and for several weeks after you stop the medication, to allow all traces of the drug to to be eliminated from your body. Foods and to eliminate from your diet include the following specific types, as well as any combination foods (such as soups, stews, casseroles, stir-fries, and baked goods) that may include these as ingredients, as well as certain other types of drugs and supplements:2, 4, 5, 6

Aged, fermented, pickled and air-dried meats, poultry and fish. To include salami, dried sausages such as mortadella, jerky, aged chicken livers, smoked salmon (lox), caviar, and pickled herring, as well as any animal foods that have spoiled or have been improperly stored. (Tyramine levels increase in foods when they are held at room temperature.) Also avoid gravies and sauces made with meat extracts, soy products, or cheese.

  • Aged (mature) cheeses, including Cheddar, Stilton, Swiss, camembert, blue, and gorgonzola varieties.
  • Fava beans, broad beans (and their pods), snow peas, and most soybean products (with the exception of soy beverages).
  • Dried fruit such as raisins, apricots, and prunes. Oranges, grapefruit, lemons, limes, and pineapple contain small amounts of tyramine and should be limited to no more than 1/2 cup per day. Other fruits are fine but avoid any that are overripe.
  • Fermented and pickled foods such as sauerkraut, kimchi, miso, pickles, pickled vegetables, Asian fish sauce, soy sauce, fermented bean curd (tofu). and concentrated yeast extract products such as Marmite and Vegemite.
  • Beer on tap and unpasteurized or home-brewed beers. (Canned and bottled beers have been pasteurized, which prevents further fermentation and production of tyramine.) Vermouth and Korean beers are also known to be high in tyramine.
  • Protein supplements and supplemental products, especially those promoted for weight loss and body-building. Check the ingredient list for any form of tyramine, including L-tyramine, N-Methyl-L-Tyramine HCL and N-Methyltyramine HCL.

Additionally, speak to your health care provider or pharmacist before you take any prescription or over-the-counter products for weight reduction, allergies, sinus, cold, cough or flu, or mood (including herbal products such as ginseng or St. John’s Wort.) Make sure your prescriber is aware of all medications and supplements you take for any reason.

“Be especially careful with cough and cold medications, decongestants, antihistimes, and any other products that contain epinephrine, pseudoephedrine or phenylpropanolamine (banned in the U.S and many other, but not all, countries),” Dr Edlund warns. “When combined with MAOIs, these substances can cause the same problems with hypertension as tyramine, leading to increased heart rate and stroke.”


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Last Updated: Jan 8, 2021