念慈庵枇杷膏 works very well. Most of the 中药店 sell them, some Chinese grocery stores also carry them. At one point, I saw them at Loblaws; it is known as "Nin Jiom Pei Pa Kao - Herbal Cough and Throat Syrup".
I like to take (drink) 枇杷膏 mixed with some hot water. I finds it is very soothing for the throat ... even the children like it. 念慈庵枇杷膏 is a MUST have 中药 in our house.
Hope it works for you.