Can Long Term Usage Of Levocet Cause Any Side Effects?

frequent stuffy nose,difficulty in breathing; diagonised as primarily due to allergy ,along D.S and sinus problem.using Levocet daily evening which gives relief but feels fatigue next day. is it okay to continue using the drug for long, or is there any other medicine safer & more effective? male ,64 yrs , on drugs for HT and mild BPH.