I am undergoing chemotherapy for metastatic breast cancer. My treatment includes intravenous doxyl. On Thursday, I received a prescription of citalopram hydrobromide (20mg) to address my feelings of depression. I am also using tamazepan (?) for sleeping problems. Yesterday, I felt fine. However, today I am outrageously sleepy. I have slept most of the afternoon. I know my chemo can cause drowsiness, but that has never occurred on the second day. Usually, the drowsiness sets in several days after the treatment. Is there an adverse interaction between my medications that is causing this sleepiness?

Thank you.