Within the system organ classes, undesirable effects are listed under headings of frequency, using the following categories: very common ( 1/ 10); common ( 1/ 100 to < 1/ 10); uncommon ( 1/ 1,000 to < 1/ 100); rare ( 1/ 10,000 to < 1/ 1,000); very rare ( 1/ 10,000), not known (cannot be estimated from the available data). Within each frequency grouping, undesirable effects are presented in order of decreasing seriousness