Is it safe to give my child a dose of activated charcoal to cure his diarrhoea?
Depends on how old the child is and how serious the diarrhea is also. But in general, if the child is very young (less than 4), you should not attempt to self treat a child. Most over-the-counter medications (and actually most medications) have not been studied extensively in children regarding their safety. Furthermore, simple illness such as diarrhea may be harmless to adults like us, but in children, they can be very serious and lead to complications. My suggestion would be take him/her to a pediatrician to have them evaluate the condition. In the meantime, keep the child well-hydrated with pedialyte or just regular water.