Make up for a missed intake at once if you are reminded of it. But if the next dose on your schedule is already due, leave out the missed dose and take the succeeding one according to prescription. Taking Flexeril in excess can be fatal. If you incur symptoms of excessive use, such as a quick heartbeat, tremors, hallucinatory visions, chest pains, or seizure (convulsion), get medical attention as soon as possible. Keep Flexeril away out of children’s reach. Store it at 25C, or within controlled temperatures of 15-30C.