Currently, there is no information regarding any negative long term effects of taking bromelain. As you may know, bromelain is a proteolytic enzyme naturally derived from the pineapple plant. Due it is natural origin and gentle mechanism of action there are no foreseeable problems regarding long term use particularly if you are finding it helpful in managing your arthritis symptoms. It is certainly a better option than using other more harmful over the counter or prescription anti-inflammatories that can severely damage the gastrointestinal tract. However, people with certain bleeding disorders or with pre-existing stomach ulcers or other digestive problems should consult with a physician before using bromelain as it may cause these conditions to worsen.
If you are still concerned, often I will recommend that people take a break of 2 weeks from certain supplements after about 8-10 weeks of consecutive therapy. This gives the body a chance to have a break and can help ensure that product remains to be effective for you in the long term. If you find that your symptoms return quickly when you discontinue it, you can shorten your break to just a few days.