MAOIs (Monoamine Oxidase Inhibitors)

What MAOIs are

Monoamine oxidase inhibitors (MAOIs) are one of the oldest classes of antidepressant medicine, first introduced in the 1950s. They work by blocking monoamine oxidase, an enzyme that breaks down chemical messengers such as serotonin, norepinephrine and dopamine. Their discovery played an important part in the history of psychopharmacology and in early theories about the biology of depression.

Today MAOIs are prescribed far less often than newer antidepressants, mainly because they require careful attention to interactions with certain foods and other medicines. They remain an option that specialists may consider in particular circumstances. The first MAOI, iproniazid, was originally developed to treat tuberculosis, and its mood-lifting effects were noticed by chance, a story often used to show how unexpected observations can lead to new scientific ideas.

Talking to a professional

Because of these interactions, MAOIs need close supervision by an experienced prescriber. Any questions about starting, stopping or switching medicines should be discussed with the prescriber or a pharmacist, never decided from general information.

Relevant professionals include psychiatrists, primary care doctors (GPs) and pharmacists. Psychologists and licensed therapists provide evidence-based talking therapies for depression.

Before an appointment, it can help to note down your questions, what you have noticed and any medicines you already take. It is reasonable to ask about the options available, what the research says about them and what happens next. Good clinicians welcome questions and explain things in plain language.

Learn more

To learn more, see our pages on depression, the difference between psychiatrists and psychologists and types of therapy. Our guide to types of mental health professionals explains who does what.