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. Author manuscript; available in PMC: 2023 Jan 1.
Published in final edited form as: Cancer J. 2022 May-Jun;28(3):208–223. doi: 10.1097/PPO.0000000000000591

Table 4.

World Health Organization (WHO) Council for International Organizations of Medical Sciences (CIOMS) Classification of Frequency of Drug Reactions

Very common >1/10 (>10%)
Common (frequent) >1/100 and <1/10 (>1% and <10%)
Uncommon (infrequent) >1/1,000 and <1/100 (>0.1% and <1%)
Rare >1/10,000 and <1/1,000 (0.01% and <0.1%)
Very rare <1/10,000 (<0.01%)