"I was prescribed flexeril for migraines and it was the WORST experience of my life. After developing a migraine, I took one 5mg flexeril in the afternoon and, about 6 hours later, one 50mg tramadol and one 100 mg imitrex. I ended up in the ER at 3 o&#039;clock in the morning unable to breathe, barely able to move and in a full blown panic attack. Apparently, flexeril is similar in chemical make up to Elavil  - a drug a had a VIOLENT reaction to! - and can cause something called serotonin syndrome (which is what I had) when taken with tramadol. Why didn&#039;t my doctor know this?? Why was I never warned that flexeril should NOT be taken with tramadol due to possible dangerous interactions. I&#039;ll NEVER take this dangerous drug again."