It?s normal for nostrils to alternate airflow due to the nasal cycle, but if you have allergy or blockage, medicines can help. Allrite DC can be taken if prescribed, as it reduces allergy and nasal congestion, but use it only for the duration advised since decongestants are not meant for long-term daily use. Also try steam inhalation and saline nasal spray. If blockage continues for long or you depend on tablets regularly, consult an ENT doctor to check for allergy or structural issues.