The combination of moclobemide with prescription or over the counter sympathomimetic drugs is not recommended due to the potential of significant drug interactions. Serotonin syndrome has been reported when moclobemide has been taken in combination with other serotonin enhancing drugs; however, due to moclobemide's reversible MAO inhibition, serotonin syndrome is significantly less likely to occur with moclobemide than with older irreversible MAOIs. Serotonin syndrome has been reported when trazodone was abruptly replaced with moclobemide. Taking at the same time or starting moclobemide too soon after discontinuing clomipramine or serotonin reuptake inhibitors such as SSRIs may result in the development of a serotonin syndrome. SNRIs such as venlafaxine in combination with moclobemide have also been associated with serotonin syndrome. Cimetidine causes a doubling of the blood plasma levels of moclobemide. Blood plasma levels of trimipramine and maprotiline and possibly other tricyclic antidepressants increase when used in combination with moclobemide and may require dosage adjustments if the combination is used for treatment resistant depression. The elimination of zolmitriptan is reduced by moclobemide and if the combination is used, a dosage reduction of zolmitriptan is recommended. Moclobemide reduces the metabolism of dextromethorphan. Moclobemide may decrease metabolism of diazepam, omeprazole, proguanil, propranolol and others due to inhibition of CYP2C19. Dietary Irreversible MAOIs can cause unpleasant and occasionally dangerous side effects such as a hypertensive crises after intake of food or drink containing indirectly acting sympathomimetic amines such as tyramine. This is sometimes referred to as the 'cheese effect'. These side effects are due to irreversible inhibition of MAO in the gut and vasomotor neurones. However, the reversible MAOI antidepressants such as moclobemide have a very different side effect profile in this regard. The reversible binding to MAO-A by moclobemide allows amines such as tyramine to displace moclobemide from MAO-A allowing its metabolism and removing the risk of a hypertensive crisis that occurs with irreversible MAO inhibition. Of 2300 people in multiple clinical trials who were treated with moclobemide in doses up to 600 mg with no dietary restrictions, none experienced a tyramine-mediated hypertensive reaction. As the pressor effect of moclobemide is so low, dietary restrictions are not necessary in people eating a normal diet, in contrast to irreversible MAOIs. However, some rare cheeses that have a high tyramine level may possibly cause a pressor effect and require caution. The potentiation of the pressor effect of tyramine by moclobemide is only one seventh to one