Честотите се определят като: много чести (≥ 1/ 10); чести (≥ 1/ 100 до < 1/ 10); нечести (≥ 1/ 1 000 до < 1/ 100); редки (≥ 1/ 10 000 до < 1/ 1 000), много редки (< 1/ 10 000 вкл. отделни съобщения).
Frequencies are defined as: 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 including isolated reports).