I have a 30ml bottle full of mixed flavours, mixed strengths. There is no reason I can think of why I should not use it - but somehow it is kept for an emergency, which, with my 1/2 litre 36mg tasteless tucked away, is going to be so far in the future I don't have to think about it now. But I cannot bring myself to throw it away and since I am now using teabag/paper towels instead of filler I won't be adding to it. So I guess it will just sit there until I make a decision.