There's a range of options available at the local pharmacy if you're suffering from catarrh. There are the mucolytics, which dissolve phlegm, and which can be taken by mouth and as an inhalant, and the decongestants, which come either as nasal spray
Both come with a range of side effects which are worth noting before you begin a course of treatment.
The decongestant sprays can cause swelling of the lining of the nose, while oily nasal solutions have on occasions brought on pneumomia. Dryness and irritation of the nasal cavity can also occur, while inhaled mucolytics could cause wheezing.
Asthmatics should avoid all mucolytics, and infants should never be given decongestants as body temperature can fall rapidly and dangerously, possibly causing a coma. Adults can suffer the same fate if they take enough of the drug.
If your catarrh is persistent, you might do better by suspecting an allergy, or a smoker in the house, or an excess of dairy or wheat products in your diet.