Tyramine and irreversible monoamine oxidase inhibitors in clinical practice.

The cheese reaction following use of the irreversible monoamine oxidase inhibitors (MAOIs) began to be reported in the UK with increasing frequency from about 1961. By 1965, the underlying mechanism (tyramine-provoked hypertension) had been essentially elucidated. Thereafter, this potentially severe side-effect could have been largely avoided by the use of fairly simple dietary precautions. Unfortunately, suspicion and fear burgeoned, and both the seriousness and the frequency of risk were dramatically inflated. This was a major factor in the subsequent general disuse of the irreversible MAOIs. Second-generation MAOIs which are selective for monoamine oxidase-A and B are now being synthesised and may eliminate the eventuality of hypertension without special dietary precautions.