Median time to recovery was 17 days ( 95 % CI 14-19 ) in the regular group , 17 days ( 15-20 ) in the as-needed group , and 16 days ( 14-20 ) in the placebo group ( regular vs placebo hazard ratio 099 , 95 % CI 087-114 ; as-needed vs placebo 105 , 092-119 ; regular vs as-needed 105 , 092-120 ) .