Just know if you decide to use the Robitussin make sure there are no additives in it.
Guaifenesin is what you need. You can also utilize
the generic brand which is called Tussin or even
the store brand (i.e. Walgreen's, CVS, etc.)...not sure if these are in Canada. There are several types of Robitussin (i.e. Robitussin DM, Robitussin C, Robitussin D, etc.) These all have additional active ingredients in them like Dextromethorphan HBr which is a cough suppressant and you do not need that.