I need to verify a few statements before processing. If any of these statements are true I need to do something. I tried

if exists (select patid from pat..patientallergies where patid = @patid and facid = @newfacid )
or
if exists (select patid from pat..reorders where patid = @patid and facid = @newfacid )
or
if exists (select patid from pat..ReorderDirections where patid = @patid and facid = @newfacid )
begin

However this syntax is not allowed. What would be the proper way to do this?