There is some confusion regarding Trazodone here. First, you can take two SSRI's together if your doctor has prescribed it. Second, Trazodone according to the Nursing Drug Reference 2006 states that its action is to: Selectively inhibit serotonin, norepinephrine uptake by brain, potentates behavioral changes. Third, it is used according to the same reference for Depression and Chronic Pain
There is an interaction warning with taking it in conjunction with SAM-e and or St. John's wort.
Also a possible hypersensitivity to other tricyclics. You are not taking any tricyclics as you are on Lexapro.