RT Journal Article SR Electronic T1 How to use antihistamines JF Canadian Medical Association Journal JO CMAJ FD Canadian Medical Association SP E478 OP E479 DO 10.1503/cmaj.201959 VO 193 IS 14 A1 Chu, Derek K. A1 Oykhman, Paul A1 Sussman, Gordon L. YR 2021 UL http://www.cmaj.ca/content/193/14/E478.abstract