I have extraordinary sciatica pain - saw my doctor today and she prescribed 500 mg twice a day of Naproxen. Have taken two today, one just a few hours ago. It is not working nearly as well as the extra strength Advil I had been using. I don't suppose it is a good idea to take Advil now? Also, I have some Tylenol with codeine left over from dental surgery -- would it be a bad idea to take it while I have Naproxen in my system? Any help appreciated. Doctor also gave me a prescription for a muscle relaxant to be taken at bedtime. Haven't taken it yet.