If you have been prescribed a monoamine oxidase inhibitor, known as an MAOI, a slice of aged cheddar or a plate of salami can push your blood pressure into dangerous territory within minutes.
The risk is well documented in FDA drug labeling and by major hospital systems, yet counseling for patients starting these drugs is often incomplete.
MAOIs block the enzyme monoamine oxidase, which normally breaks down a compound called tyramine found in aged, fermented and spoiled foods.
With the enzyme blocked, tyramine builds up quickly and can trigger a sudden surge in blood pressure that may need emergency care.
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How little tyramine it takes
In a review published in the Journal of Clinical Psychiatry, pharmacologist David A. Flockhart reported that just 6 to 10 milligrams of tyramine can trigger a mild reaction in someone on an irreversible MAOI, and 10 to 25 milligrams a severe one.
Hypertensive crisis is defined as systolic pressure above 180 mm Hg or diastolic pressure above 120. Warning signs include severe headache, a pounding or racing heartbeat, neck stiffness, sweating, nausea and chest pain.
In rare cases the pressure surge can trigger a brain bleed, which can be fatal, the Cleveland Clinic warns.
The foods to be careful with
Aged cheeses top the list. That includes cheddar, Swiss, Parmesan, blue cheeses such as Stilton and Gorgonzola, feta, brie and Camembert.
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Cured and fermented meats belong on it too, including salami, pepperoni, dry sausage, liver and anchovies, along with smoked or pickled fish.
Fermented soy products, such as soy sauce, miso and tempeh, are also tyramine-rich, as are yeast extracts like Marmite.
Draft or tap beer is singled out because unpasteurized brews can be tyramine-heavy. Sauerkraut, fava beans and overripe or spoiled fruit round out the main list.
A StatPearls chapter maintained by the National Library of Medicine flags overripe fruits, avocados, bananas, raisins and figs, since tyramine levels rise as food ages.
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MedlinePlus, the federal drug-information service, notes that patients on phenelzine should also avoid caffeine. A doctor or dietitian should explain which foods to skip entirely and which are acceptable in small amounts.
Which drugs are MAOIs
Only four MAOIs are approved in the United States. They are phenelzine, sold as Nardil, tranylcypromine, sold as Parnate, isocarboxazid, sold as Marplan, and selegiline, sold as the Emsam skin patch.
All four are typically reserved for patients who have not responded to other treatment options, according to StatPearls, which is why they remain a key tool for treatment-resistant depression.
If you take an SSRI or SNRI
Most people taking antidepressants today are not on an MAOI. Selective serotonin reuptake inhibitors, known as SSRIs, and serotonin-norepinephrine reuptake inhibitors, or SNRIs, work through a different mechanism and do not block the enzyme that clears tyramine.
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Cheese, cured meats and beer do not carry the same blood-pressure risk on those drugs.
Anyone unsure which class their medication belongs to can ask a pharmacist. Any patient with symptoms of a hypertensive crisis, especially a sudden severe headache with chest pain or a racing heart, should seek emergency care.
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This article is made and published by Jesper Bengtson, who may have used AI in the preparation.