MAO inhibitors have largely been supplanted in therapy because of their high risk of significant side effects, most notably severe, possibly fatal high blood pressure, if foods or alcoholic beverages containing tyramine are consumed.
SSRIs should not be used with any drug that increases serotonin concentrations, including MAO inhibitors, tramadol, sibutramine, meperidine, sumatriptan, lithium, St. John's wort, ginkgo biloba, and some anti-psychotic agents.
When antidepressants are prescribed for episodes of bipolar depression, they are usually selective serotonin reuptake inhibitors (SSRIs) or, less often, monoamine oxidase inhibitors (MAO inhibitors).
Studies on MAO inhibitors have only been performed on adult patients, and there is as of 2004 no specific information comparing the use of MAO inhibitors in children with use in other age groups.
A rapid, potentially fatal increase in blood pressure can occur if foods or alcoholic beverages containing tyramine are ingested by a person already taking MAO inhibitors.