Do collagen supplements work !?

For what: your question could be a bit more specific--for injections it can help for cosmetic purposes. For taking it for arthritis or to support joints, there is no good data that it does anything. Avoiding smoking will help project the collagen in your body.

Maybe not: There are thousands of supplements advertised to do all sorts of magical remedies. Very few supplements have real research studies to show benefits (but manufacturers make claims, based on theories, animal tests, testimonials, chemical similarities, etc... but not based on real research because real research is hard to do and is expensive to do).