Tyramine (TIE-ruh-meen) is an amino acid that helps regulate blood pressure. It occurs naturally in the body, and it's found in certain foods. Medications called monoamine oxidase inhibitors (MAOIs) block monoamine oxidase, which is an enzyme that breaks down excess tyramine in the body. Blocking this enzyme helps relieve depression.

If you take an MAOI and you eat high-tyramine foods, tyramine can quickly reach dangerous levels. This can cause a serious spike in blood pressure and require emergency treatment.

Avoid consuming foods that are high in tyramine if you take an MAOI. You may need to continue following a low-tyramine diet for a few weeks after you stop the medication.

Tyramine occurs naturally in small amounts in protein-containing foods. As these foods age, the tyramine levels increase. Tyramine amounts can vary among foods due to different processing, storage and preparation methods. You can't reduce the amount of tyramine in a food by cooking it.

Examples of foods high in tyramine include:

• Strong or aged cheeses, such as aged cheddar, Swiss and Parmesan; blue cheeses such as Stilton and Gorgonzola; and Camembert. Cheeses made from pasteurized milk are less likely to contain high levels of tyramine — for example, American cheese, cottage cheese, ricotta, farmer cheese and cream cheese.
• Cured meats, which are meats treated with salt and nitrate or nitrite, such as dry-type summer sausages, pepperoni and salami.
• Smoked or processed meats, such as hot dogs, bologna, bacon, corned beef or smoked fish.
• Pickled or fermented foods, such as sauerkraut, kimchi, caviar, tofu or pickles.
• Sauces, such as soy sauce, shrimp sauce, fish sauce, miso and teriyaki sauce.
• Soybeans and soybean products.
• Snow peas, broad beans (fava beans) and their pods.
• Dried or overripe fruits, such as raisins or prunes, or overripe bananas or avocados.
• Meat tenderizers or meat prepared with tenderizers.
• Yeast-extract spreads, such as Marmite, brewer's yeast or sourdough bread.
• Alcoholic beverages, such as beer — especially tap or homebrewed beer — red wine, sherry and liqueurs.
• Combination foods that contain any of the above ingredients.
• Improperly stored foods or spoiled foods. While you're taking an MAOI, your doctor may recommend eating only fresh foods — not leftovers or foods past their freshness dates.

Beverages with caffeine also may contain tyramine, so your doctor may recommend limits.

MAOIs, although effective, generally have been replaced by newer antidepressants that are safer and cause fewer side effects. Still, an MAOI is a good option for some people. In certain cases, an MAOI relieves depression when other treatments have failed.

Examples of MAOIs that are used for depression include:

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

Selegiline in patch form (Emsam) delivers the medication through your skin. If you use the lowest dose of the patch, you may not need to be as strict with the foods you eat, but check with your doctor or pharmacist.

It's wise to learn the emergency signs of a rapid and severe rise in blood pressure (hypertensive crisis), which may include:

• Severe headache
• Nausea and vomiting
• Sweating and severe anxiety
• Nosebleeds
• Fast heartbeat
• Chest pain
• Changes in vision
• Shortness of breath
• Confusion

Rarely, a severe increase in blood pressure can lead to bleeding in the brain (hemorrhagic stroke).

If you take an MAOI, be prepared. Ask your doctor:

• For a list of foods to avoid — make sure you understand exactly what's safe for you and what isn't
• What to do if you accidently eat or drink something with too much tyramine, so you have a plan in place