It’s been nearly 5 months since “The Real Housewives of Orange County” star Lauri Peterson announced the passing of her son, Josh Waring … and TMZ has learned what caused his death.
California’s Orange County Sheriff-Coroner Department tells TMZ … the Bravo personality’s late son died from the combined effects of fentanyl, methamphetamine and olanzapine — with the death officially ruled “accidental.”

