Colosan works very well for me whenever I take it. Works much better than products found in the pharmacy. What's very interesting, is that The Finchley Clinic recommend avoiding taking Vitamin C for a couple of hours around when taking colosan.
At one point I did take them together and found that colosan stopped working. I then went back to read the information on the colosan, where I noticed the advice not to mix it with Vitamin C. So I separated them out, and colosan immediately began working again. So please follow The Finchley Clinic's advice!