I have been using Endovan for 4 years. It is the only thing I have found for pain relief. I don’t know how it works only that it does. Also keeps me from having PMS. I have recommended to several people who have tried it and LOVE IT. The only thing I don’t is the cost. I haven’t ever been able to go down to one tablet twice a day. I have to be on two tabs twice a day. Gets costly, but worth it.