Dexona is a steroid and is to be taken only when there is allergy that does not respond to simple anti-allergy drugs like cetirizine (sold under the brand name of Ceticad) 10 mg once daily for 4-5 days. Avil causes lot of drowsiness and reduces alertness and hence driving is prohibited. It is better to take Ceticad. Erythromycin has no role in allergy. It is an antibiotic.