Phenocane was recommended to me by a massage therapist -nothing seemed to be helping my nagging lower-back and knee pain and I was not happy to be taking Ibuprofen almost daily. I bought a bottle and took one, not really expecting much - went to the gym and played racquetball for an hour and a half. Then it hit me - I couldn't have done that unless the pain had been reduced! For me, it works better than 2 Ibuprofen, lasts 6-8 hours and I observe no side effects whatever. For this active 55 yr old, this stuff works great!