There have been reports of allergic reactions to bromelain. Other known side effects of this supplement include nausea, vomiting, diarrhea, and menorrhagia (excessively heavy menstrual flow).

As with most things, moderation is the key. Bromelain has been demonstrated to be generally safe when taken in moderate doses. One preliminary report links an increased heart rate with the use of the supplement. People with an inflammation of the stomach lining should not use digestive enzyme supplements such as bromelain. In addition, the safe use of bromelain in pregnant or nursing women, small children, and people with kidney or liver disease has not been established.

People who are allergic to pineapple or pineapple juice should not use this product.