Hello denmark ,

What works well for me with the asthma and the mucus in the back of my throat, is the product named, TUSSIN/Cough Formula.

This is a Guaifenesin Oral Solution/Expectorant.

The 'thing' one must know is that MOST Guaifenesin OTC liquids contain MENTHOL. Which is something asthmatics are to AVOID.

Therefore I purchase the CVS TUSSIN C/F which is alcohol/menthol free! This is also available at Walgreens, I am told.

The key here, denmark, is to get the Tussin with the code #31034 on the back of the bottle, on the lower- right hand corner.

I DO NOT have a cough with my asthma, but I DO HAVE THE MUCUS in the back of my throat, and upper chest (sometimes).

I hope this will help your son.

Blessings, Abishag <><