 [ Symptoms ] can lexapro be taken simultaneously with dextromethorphan hbr i had acute endo carditis 2004 and had emergency surgery to replace my mitral valve with a porcine valve i am now 71 and have a viral infection that is not responding to a z pac i started on adult tussin dm nd mucinex this morning worried that this may not be good for me because i take lexapro 10 m daily [ Disease ] i checked them in the interaction checker and found this serious   use alternative potential for serious interaction regular monitoring by your doctor required dextromethorphan + lexapro oral lexapro oral and dextromethorphan both increase affecting serotonin levels in the blood too much serotonin is a potentially life threatening situation severe signs and symptoms include high blood pressure and increased heart rate that lead to shock <link>