I use it for 28 days the rabbits love it , i am told that its more thorough than Panacureni a referring to the risk of a parasite called E.Cuniculi. It is present in approximately 50% of domestic (not wild) rabbits. It is a small protozoan parasite that is typically spread from mum to babies or via urine- such as rabbits mixing on the same area of grass or run- eating grass that could have previously had urine on it from an infected rabbit.
The only way to effectively treat or prevent E.Cuniculi is a 28 day course of an oral aniseed flavoured liquid called Lapizole. It only needs to ever be done once unless your rabbit is due to mix with new rabbits at any stage again in the future- in which case it should be done each time.
A bottle of lapizole is around £14 from online supplyersvand has sufficient in it to treat a 3kg rabbit for the full course. Its easy to give- they love the taste.
I would use it as i don't like the end result of the parisite infection Symptoms may never appear but they can include head tilt, kidney failure, bladder infections, incontinence, weakness and paralysis. Treatment once they have symptoms often is too late.