If you have a blocked or runny nose, chances are you’ll reach for a tissue or hanky to clear the mucus by having a good blow. But is there a right way to blow your nose? Could some ways make your cold worse? And could you actually do some damage? The three most common reasons for extra mucus or snot are the common cold, sinusitis, and hay fever. Each of these conditions cause the lining in the nose to swell up, and to produce extra mucus to flush away infection, irritants or allergens. Both the swelling and extra mucus lead to nasal congestion. This is when the narrowed passages increase the effort of breathing through the nose. Clearing the mucus by blowing the nose should reduce this congestion somewhat.
At the beginning of colds and for most of the time with hay fever, there’s lots of runny mucus. Blowing the nose regularly prevents mucus building up and running down from the nostrils towards the upper lip, the all-too-familiar runny nose. People tend to repeatedly sniff thick mucus back into their nose or allow it to dribble down their upper lip. Keeping this mucus (rather than blowing it out) is thought to contribute to a cycle of irritation that causes the snotty nose to persist for weeks or longer.
This may be due to the retained mucus acting as a good “home” for bacteria to grow in, as well as fatigue of the “hairs” that cleanse the nose by moving along mucus and carrying with it irritants, inhaled debris and bacteria. Thick retained mucus is also more likely to be transported to the throat rather than gravity working it from the nostrils, leading to throat irritation and possibly a cough. This is the mechanism behind the most common cause of prolonged cough after a viral infection or hay fever, known as the post-nasal drip cough.
To sum up, if you have mucus in the nose, it is probably best to get it out, so blow gently or by clearing one nostril at a time. Use of appropriate treatments can lessen the need to blow, and the force required to clear your nose. If you are repeatedly blowing your nose you probably have a nasal condition, like hay fever or sinusitis, which should be treated more comprehensively.
