I have had chronic pain for the past 10 years and have been on just about any pain medication you can think of. While I am still on a daily 'maintenance' pain med, I was also taking 2-4 percocet a day for 'break-through pain). I read about Willow Bark in a chronic pain book I'm reading (it was used for pain 1-2 centuries ago). I thought I'd give it a try. When I feel the need for Percocet, instead I take 2 tablets of Willow Aid and it works just as good (without any negative side effects an opiad would have). I'd say it works well for me for about 3 hours. I take 2 at a time and have never needed more than 4 tablets a day. Lisa - California Amazing but true, and I would know! This is THE best supplement I have ever tried for pain (and I used to work at a homeopathic pharmacy!