If you blow your nose too hard, you can potentially send enough pressure up the tubes that connect the ears to the back of the nose and rupture your eardrum, but you’d have to blow pretty hard to do that. The main thing with blowing your nose too vigorously is that it can cause it to bleed – too much pressure can cause blood vessels to burst – but it’s never usually dramatic. You may just notice some bloodstains on your tissue.
You can blow both nostrils at the same time, but you may have a deviation in the midline partition – the septum – which may make it difficult. You may find it easier to do one, then the other.
Blowing your nose is mostly for comfort – most people do it because they have a feeling of excess mucus in their nose. We all produce a pint and a half of mucus every day, which we swallow without noticing. Most of the time, you blow your nose because you have an excess of mucus production – you have a cold, nasal allergy, hay fever or other condition. If you work in a polluted environment, blowing your nose is a way of clearing out mucus that has collected debris and pollutants from the atmosphere.
Nasal douching with a saline solution is a technique doctors recommend for patients with various nasal disorders, such as allergies and people with rhinosinusitis (nasal inflammation), and an additional way to clear excess mucus. You can get a kit from your pharmacist or supermarket.