Depends on what is meant by long time!!Glucosamine may adversely affect sugar levels in diabetes. These supplements are recommended in early stages of osteoarthritis. If no significant relief is appreciated in 3-6 weeks further usage may not be of much help. Kidney function and Other systemic diseases also may not warrant long term usage of these supplements. In the absence of any other systemic illness and in early arthritis, it is recommended to be used for 6 months to a year without any significant side effect