How long before glucosamine takes effect?

Glucosamine has been shown to be no better than placebo in numerous studies now. However, despite this fact, many people perceive benefit, in terms of decreased joint pain, when taking glucosamine (and/or chondroitin sulfate). Most clinicians ascribe this response to the placebo effect. In any case, the response is quite variable, with approximately one third of people reporting some response, at least, after a few weeks or so, and two thirds reporting no response at all.