Why does one nostril always feel blocked?

Some one-sidedness is normal: your nose runs a natural cycle, quietly swapping most of the airflow between your nostrils every few hours, so at any moment one side feels clearer and the other stuffier - and you notice it most in bed, when the lower nostril congests from lying down. A congested nose is simply swollen lining tissue, per MedlinePlus, and swelling pools where gravity sends it. The pattern that means something is different: the SAME side blocked all the time, every position, every day. The most common structural reason is a deviated septum - the wall between your nostrils sits off-centre and narrows one passage; MedlinePlus lists it among the most common nose disorders, and most people have at least a slight deviation without knowing. Enlarged turbinates, nasal polyps, and old injuries do the same job. Allergies make everything worse by swelling the lining further. Worth trying first: a saline rinse or spray to clear the lining, a steroid nasal spray daily for a few weeks if allergies are in the mix, and sleeping slightly propped. The see-a-GP lines: one side always blocked despite that, discharge that comes from only one side (MedlinePlus flags one-sided discharge as a get-checked sign), frequent one-sided nosebleeds, or blocked breathing that wrecks your sleep. A deviated septum that truly obstructs can be straightened surgically. Pymander is a free AI doctor, 24/7 by text, that can help you weigh the pattern.