I am allergic to shellfish, and i can't take glucosamine. is there another alternative for arthritis?

No need to: New data from a long-term study of the dietary supplements glucosamine and chondroitin for knee osteoarthritis pain reveal that patients who took the supplements (alone or in combination) had outcomes similar to those experienced by patients who took Celecoxib or placebo pills.

Other supplements: Consider other supplements that are natural anti-inflammatories. Ginger, green tea, turmeric, rosemary and omega-3-fatty acids are some examples. A popular brand name containing many of these supplements is zyflamend. Some also recommend msm, although there is little scientific evidence of a benefit with osteoarthritis.