Can I take Phenelzine and Tyramine together?

Why this happens

Phenelzine is a Monoamine Oxidase Inhibitor (MAOI). It works by blocking an enzyme (MAO) that normally breaks down tyramine in your gut and liver. When this enzyme is blocked, tyramine from your food enters your bloodstream in large amounts. This causes your body to release a surge of adrenaline-like chemicals, which makes your blood vessels tighten and your blood pressure soar.

What you should do

You must follow a strict 'low-tyramine' diet while taking phenelzine and for at least two weeks after stopping it. Avoid aged cheeses, yeast extracts (like Marmite), soy sauce, broad beans, pickled herrings, and cured or fermented meats (like salami). Only eat fresh foods and avoid anything that is aged, fermented, or spoiled. If you develop a sudden, severe headache, seek emergency medical help immediately.

Important precautions

Hypertensive crisis (dangerously high blood pressure)

You must strictly avoid foods containing tyramine (such as aged cheeses, yeast extracts like Marmite, cured meats, and draught beer) while taking phenelzine and for 14 days after stopping. Combining them can cause a life-threatening spike in blood pressure.

Serotonin syndrome and drug interactions

Phenelzine has dangerous interactions with many other medicines, including other antidepressants, certain painkillers (like pethidine), and cold/flu remedies. Combining these can cause serotonin syndrome, a potentially fatal condition.

Suicidal thoughts and self-harm

Phenelzine can increase the risk of suicidal thoughts or self-harm, particularly when first starting treatment or changing the dose. Monitor your mood closely and seek urgent medical help if you experience distressing thoughts.

Use of over-the-counter cough and cold remedies

Many non-prescription medicines, especially decongestants, can cause dangerously high blood pressure if taken with phenelzine. Always check with a pharmacist before taking any other medicine.

Food and drink warnings

Tyramine-rich foods (e.g., aged cheeses, cured meats, yeast extracts)

Phenelzine is a Monoamine Oxidase Inhibitor (MAOI). Consuming foods high in tyramine can cause a sudden, dangerous rise in blood pressure (hypertensive crisis). You must follow a strict low-tyramine diet while taking this medicine and for two weeks after stopping it. Avoid aged cheeses (like cheddar or camembert), pickled herrings, salami, pepperoni, and Marmite. Only eat fresh foods.

Alcohol (specifically draught beers and Chianti wine)

Avoid draught beers, real ales, and certain wines like Chianti, as they contain high levels of tyramine. Most spirits and bottled lagers are lower in tyramine, but alcohol can also increase the sedative effects of phenelzine. It is safest to avoid alcohol or consult your pharmacist for a specific list of safer options.

Caffeine (Coffee, tea, cola, energy drinks)

Phenelzine can increase your sensitivity to caffeine. Consuming large amounts may lead to high blood pressure, a racing heart, or jitteriness. Limit your intake of caffeinated drinks.

Broad beans and fermented soya products

Avoid broad beans (fava beans) as they contain levodopa, which can react with phenelzine to raise blood pressure. Also avoid fermented soya products like soy sauce, miso, or tofu, which are high in tyramine.

Chocolate

Eat chocolate only in moderation. It contains small amounts of phenylethylamine, which can occasionally cause reactions like headaches or high blood pressure when taking this medicine.

Using other medicines

Taking multiple medicines? Our Medicines Interaction Checker helps you check whether your prescriptions, over-the-counter medicines, and supplements are safe to take together. Simply search for your medicines to see potential interactions and what to do about them.

Disclaimer

This information is for general educational purposes only and should not be relied upon as a substitute for professional medical advice. Always consult your GP, pharmacist, or another qualified healthcare professional before making decisions about your medications. Individual circumstances may vary, and only a healthcare professional who knows your medical history can provide personalised guidance.