For advanced cases of coccidia you need sulfadimethoxine. (Albon) First state vet supply sells it. Corrid won't touch advanced coccid. It's just a vitamin blocker. You need a sulfa drug. Peter Brown runs First State, he is the one who instructed me to use it. Saved my chicks. lso I use colloidal silver for unknown illnesses. Safe, natural antibiotic. Does the trick pretty much every time. However you need a powerhouse drug to kill bad Coccidia. Hope this helps.