We are often familiar with viral sinusitis, which is very commonly associated with the common cold, for example, yet there are other causes that are more or less well known.
A viral cause
This is the main cause: it occurs during a common cold, for example. The inflammation then affects the maxillary sinus, which is the most common form of sinusitis. This can be the result of nasopharyngitis that does not clear up (1).
During nasopharyngitis, inflammation of the mucous membranes can block the sinus drainage openings, leading to a build-up of mucus which then flows into the maxillary sinuses, which communicate directly with the nasal cavities.
In this case, treatment is often symptomatic. The rapid resolution of sinusitis relies on the body’s natural defence mechanisms and immune system. Regular nasal rinses will help improve your breathing comfort and provide temporary relief from symptoms(3).
A secondary bacterial infection
Sometimes, following a viral infection, the local flora becomes unbalanced or our immune system is put under severe strain. Under these circumstances, the condition may progress to bacterial sinusitis. This is referred to as a secondary infection. If you experience a combination of several of these symptoms, you should seek medical advice promptly so that a diagnosis can be made:
Pain beneath the eyes: it intensifies rather than subsiding, even after 48 hours of symptomatic treatment;
A throbbing, one-sided sensation: this sensation is more pronounced at the end of the day and when you bend your head forwards;
A runny nose: the discharge changes and becomes purulent, flowing from just one nostril.
Unlike viral sinusitis, this secondary bacterial infection is not transmitted to those around you. The bacteria involved are part of everyone’s respiratory tract flora. It is the build-up of mucus that facilitates their proliferation and allows them to take hold in an already weakened body.
A dental origin
A tooth cavity or an abscess that has not been properly treated can also cause sinusitis. The infection spreads to the maxillary sinuses, which are situated close to the tooth roots. This is a common mechanism that results in a well-recognised symptom: pain radiating towards the teeth. In this case, consult your dentist without delay.
A neglected abscess or cavity can perpetuate sinus inflammation until the source of infection is treated.
Other causes
Secondary causes can also lead to sinusitis. This is the case, for example, when our body comes into contact with a substance that triggers an allergic reaction (pollen, dust mites, animal hair).
Or when we are exposed to irritants such as pollution or tobacco, which trigger a localised inflammatory reaction.
If you experience persistent pain or symptoms that are getting worse, see your doctor promptly for appropriate treatment.