I bought a bottle of Robitussin for adults, and took the first 1/4 spoonful this morning. Thought I would start with even less than 1/2 tsp a day, to see if so little would be of any help at all.
But what an awful, disgusting taste! I can hardly get the 1/4 tsp down. I will keep it up until this first bottle is empty, and if it has had no effect by then, my taste buds will be grateful. But if it helps me it is certainly well worth the taste jolt.

white rat birte