How useful is glucosamine-chondroitin-msm in treating joint pains?

I am not sure. The theory behind using the glucosamine and chondroitin joint supplements is that more of the cartilage building blocks will be available for cartilage repair.Some study shows less pain in the joint, like when people take Motrin but real evidence of cartilage repair. Thank you.
Some feel it helps. Some of the studies suggest it may help while others do not. In the appropriate patient who wants to take it, i tell them it may or make not help. I have no reason to proactively recommend. There can be side effects: nausea, diarrhea or constipation, indigestion, upset stomach, soft stools, heart burn, the diabetic patient may have a risk of increased glucose (sugar).
Not useful. There is no good evidence that these supplements do anything. Save your money and go to the gym to exercise regularly.