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What is Nasal congestion and explain in detail?
Nasal congestion is the blockage of nasal breathing usually due to membranes lining the nose becoming swollen from inflamed blood vessels.

Background
In about 85% of cases, nasal congestion leads to  mouth breathing rather than nasal breathing. According to Jason Turowski, MD of the Cleveland Clinic, "we are designed to breathe through our noses from birth—its the way humans have evolved." This is referred to as "obligate nasal breathing."Nasal congestion can interfere with hearing and speech