DD used to have it when she was under 2 but back then it had the dosage on the bottle for under 2's.
I give it to DS occasionally (today infact) he is almost 22 months. The dosage for 2yrs is 2.5ml & I give him 1.5ml.
My children dont have any allergies or other health problems but if they did I would be alot more cautious like you I'm sure.