What is a cheese reaction caused by Nardil?

A cheese reaction to the antidepressant Nardil (phenelzine) is a serious health problem from an interaction between the drug and certain foods. People who take Nardil have difficulty breaking down a substance in some foods called tyramine. Cheeses tend to be high in tyramine, so your doctor may tell you not to consume them if you take Nardil. The same is true of foods that are pickled, smoked, aged or fermented.

If you do consume foods high in tyramine while you're taking Nardil, tyramine can build up in your blood, causing dangerously high blood pressure -- what some doctors call a hypertensive crisis caused by a "cheese reaction." The spike in blood pressure may increase your risk for stroke.