 Under the European approval, it is contraindicated in combination with St. John's Wort, which is expected to accelerate inactivation of rolapitant.In studies comparing chemotherapy plus rolapitant, dexamethasone and a 5-HT3 antagonist to chemotherapy plus placebo, dexamethasone and a 5-HT3 antagonist, most side effects had comparable frequencies in both groups, and differed more between chemotherapy regimens than between rolapitant and placebo groups.Common side effects included decreased appetite (9% under rolapitant vs. 7% under placebo), neutropenia (9% vs. 8% or 7% vs. 6%, depending on the kind of chemotherapy), dizziness (6% vs. 4%), indigestion and stomatitis (both 4% vs. 2%).