The main adverse effects of YAZ included intermenstrual bleeding [ 13 % ( 12/93 ) versus 3 % ( 3/94 ) ] , menorrhagia [ 9 % ( 8/93 ) versus 1 % ( 1/94 ) ] , nausea [ 5 % ( 5/93 ) versus 4 % ( 4/94 ) ] and skin rash [ 4 % ( 4/93 ) versus 2 % ( 2/94 ) ] .