What Medical Care Is Needed After Toddler Swallows Ibuprofen?

my 18 month old daughter haas swallowed atleast half of a 600mg ibuprofen tablet. possiobly more as there were 5 tablets on the floor and many more empty ones. but some might have been empty prior to her getting hold of it. what do i do? should i take her to my gp, a&e, or just try and get her to drink lots of water?