Your nose is usually the first indicator of environmental changes and changes to you body health. Therefore a runny nose has lots of different causes and it’s always good to run it past your GP if it goes on for too long.
Your nose, if you like, is like the canary in the coal mine, you know? It’s the first thing that detects things going on in the environment, and therefore a runny nose has lots of causes because it’s about what goes into your nose.
So probably the commonest cause of a runny nose is a cold day. So the cold air hitting your nose, just that it reacts and produces mucus, and it can become runny. Another cause would be allergy, where, you know, it’s the seasonal pollen and that goes into your nose, your nose reacts. In fact, the whole upper airway reacts, and then that reaction, that immune reaction produces fluid which then comes out of your nose.
An infection, an upper respiratory infection can cause a runny nose, again, because of the immune reaction. Some people have something called perennial rhinitis, which is almost certainly an allergy as well, but not necessarily one that, it’s more like a sensitivity in your nose to almost anything. I get it and I, you know, I sneeze and my nose runs anytime of the year, and so perennial rhinitis is really common.
The interesting thing is that if you’ve got asthma and a runny nose, the two go together by the way, rhinitis and asthma. If you’ve got rhinitis and asthma, and your asthma is difficult to control, treating the runny nose actually helps your asthma too, with a nasal steroid, but you’ve gotta talk to your GP about that. Those are the commonest causes of a runny nose.
Really rare causes are you’ve had a head injury and you can get a leak from your brain into your nose with cerebral spinal fluid coming out. It’s extremely rare, often associated with a headache, but you know, apart from that, those are the more important ones. And the other one is trauma, you know, if you’ve traumatised the nose, the nose can react and be runny as well, but the ones I’ve just mentioned are the commonest.
Dr Norman Swan, Physician and Journalist