What Is Tyramine? Foods to Avoid With MAOI Medicines

What it means

Tyramine is a natural substance formed when proteins break down as foods age, ferment or are preserved. It is found in higher amounts in aged cheeses, fermented and dry-aged meats such as salami, soy sauce and other fermented soy products, sauerkraut, some tap beers and foods that are spoiled or left out too long. Normally an enzyme called monoamine oxidase breaks tyramine down in the gut and liver, so it causes no problem.

Labels for MAOI (monoamine oxidase inhibitor) medicines, and some other medicines that block this enzyme, such as linezolid, warn about tyramine. When the enzyme is blocked, tyramine can build up and cause a sudden, dangerous rise in blood pressure. A severe headache, pounding heartbeat, chest pain, stiff neck, nausea or sweating after eating needs urgent medical help. These labels include diet advice and lists of foods to avoid.

Tyramine is not an allergen; the reaction is a chemical effect, not an allergy. It matters mainly with MAOIs; most people not taking these medicines can eat tyramine-rich foods normally.

Where you may see it

• The 'Warnings' and 'Patient Counseling' sections of MAOI labels
• Diet sheets given with MAOIs and linezolid
• Pharmacy counselling leaflets