A blocked nose (nasal congestion) occurs when the blood vessels in the nasal passages become inflamed and the tissues swell, often accompanied by excess mucus. Whether it’s from a cold, flu, allergies, or sinusitis, the feeling of being unable to breathe through your nose is frustrating. Here is a step-by-step guide to finding relief. Immediate, Drug-Free Fixes These methods work quickly by mechanically clearing mucus or reducing swelling using natural principles.