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There are a variety of factors that may cause sinusitis and sinus congestion.
It follows that sinusitis is therefore not always infectious. If, however, your sinusitis has been caused by a viral, bacterial or fungal infection, it may well be infectious.3 The problem is that even doctors and pharmacists may sometimes struggle to know what the cause is in individual patients.5,6
The most common cause of sinusitis is a viral infection.1,6 Viruses are often contagious and can be spread from person to person via coughing, sneezing, touching of hands, kissing, and so on.7,8 However, just because a virus can be transmitted to someone else doesn’t necessarily mean that it will cause a sinus infection in them too. We all respond differently to viruses.8
Experts disagree about whether sinusitis caused by a bacterial infection is contagious. Some medical websites claim that it is not.8,9 Others disagree,7 but as bacteria and fungi can be infectious agents,3 it is prudent to assume that bacterial- and fungal-related sinusitis may well be contagious.
A common misunderstanding is that having thick yellow or green excess mucus in your nasal passages and sinuses means you have a bacterial infection and therefore need an antibiotic. Evidence suggests, however, that cloudy or discoloured (brown, yellow or green) nasal mucus may be present in both bacterial and viral sinusitis1 and that mucus colour may therefore be a weak indicator of whether the infection is viral or bacterial.10
As respiratory infections can be spread by coughing, sneezing and hand-to-hand contact, the most important way to prevent transfer of the infection is good hand-washing practices, using soap or alcohol-based rubs. This is particularly important when in contact with people who are unwell.1
Minimise your exposure to environmental irritants, like cigarette smoke and pollutants, and to allergens, like dust and pollen.1