ML,
Just so happens my sinuses are well blocked and I'm almost deaf as a post in one ear.
Went to the local chemist yesterday and the Pharmacist presented me with a small white jar marked "Menthol" and "Irritant". You only need a little he said.
Got home prepared the bowl of almost boiled water and had the towel ready. Sprinkled a (generous) pinch of the crystals into the bowl and - JEEZUS - nearly blew my head off . I'm still almost deaf but my eyes have had a good watering !!