There are significant side effects related to MAOIs, and they are therefore not prescribed very often for OCD.
If individuals taking MAOIs eat foods containing tyramine, there can be a serious problem with hypertension (high blood pressure). Therefore, foods such as aged cheeses, chocolate, red wines, soy sauce, and processed meats must be avoided.
If these foods are eaten while taking MAOIs, levels of norepinephrine may rise to dangerous levels and blood pressure can skyrocket, even leading to internal hemorrhaging.
Further, do not take MAOIs in combination with other drugs that affect serotonin, as it could lead to the development of serotonin syndrome, a life threatening overabundance of serotonin, which can cause difficulties in cardiovascular functioning, coordination, digestion, and the ability to concentrate.
Other side effects can include dry mouth, insomnia, weight gain, and impotence in men or inability to achieve orgasm for women. Although these side effects are potentially severe, for some individuals who have tried all of the other medications and have not had any success, MAOIs can have some positive effects.
However, they are typically used as a last resort.