Why does common cold cause runny nose?

Cold viruses irritate cells inside the nose. Nearby blood vessels can become more leaky and the lining can swell, allowing fluid and mucus to enter the nasal passages. Early discharge may be clear and watery; it can become thicker as the illness develops. Runny Nose is a very common presentation of Common Cold. A runny nose can also occur with allergies, irritants, or other infections, so the symptom alone does not identify the cause.

Rest, drink fluids regularly, and use soft tissues to protect irritated skin around the nostrils. Saline nasal spray or drops can loosen mucus and moisturise the nasal lining. A clean humidified room may ease dryness. If you are considering a non-prescription medicine, ask a pharmacist which option is suitable for you, especially if you are pregnant, have a long-term condition, or take regular medicines.

Get urgent medical help for trouble breathing, blue or grey lips, confusion, severe drowsiness, or chest pain. Arrange medical advice if symptoms are getting worse rather than settling, if fever is persistent, or if you develop marked facial pain or swelling. Young children, older adults, and people with reduced immunity may need earlier assessment when they become unwell.

Ask whether your pattern of symptoms suggests a cold, allergy, or another cause, and which nasal treatments fit your age and health conditions. Mention the colour and duration of discharge, breathing changes, facial pain, and every medicine or nasal product you have used.