Glucosamine chondroitin is a good supplement to take if you have worn joints, from sports or from aging.  It's not a miracle pill, but it does work and it's natural.  I definetly think 2x before taking anything at all, and surely doubt anything that has potentially harmfull side effects.  However, this supplement is a good proactive measure for relieving pain in joints where cartilage has worn down from constant friction.  Knee pain is a prime example of this, thining cartilage eventually causes bones to get closer together which causes extreme pain, due to the function of the joint, it's made to hold our entire body weight.  So give this a try, you have little to lose.  These are naturally occoring substances in our bodies (Glucosamine and Chondroitin Sulfate).  Anything that's natural is way more safe (less toxic to liver and stomach) than even some of the best FDA approved drugs.  Make sure when you do purchase your supplements, that they come from a reputable company.  This is not something you would want to cut corners on, because if the standards are low, pill may look just like the one that costs 2x as much, but in the coating can be mixed in hundreds of particles that were never part of the recipe.  Raw materials that go into making the supplement maybe of low quality, process of making it is not as strict as it needs to be, and of course you get a finished product that looks like the pricy name brand, but is far from it quality wise.  Things that are in the competitors supplements are not necessarily harmful to our systems, but they may make the supplements less effective, which means you pay less per pill, but you need a greater quantity to achieve the same results.  You don't have to spend a fortune to get a good product, just do some research prior shopping.