Sinusitis can result from infection or allergy.
The sinuses are spaces in the bones of the skull which are mainly full of air. Their exact function is unclear. They stop our heads being too heavy and may play a role in helping us hear more clearly.
There are 3 pairs of sinuses and one, the sphenoidal sinus, is in the centre of the head. The maxillary sinuses are situated below the eyes on either side of the nose, the frontal sinuses are above our eyes and the ethmoid sinuses are behind the eyes. Each sinus has a narrow opening or tube connecting it to the back of the nose.
The lining of the sinuses produces a clear fluid — mucus — which constantly cleans them of unwanted material. This fluid passes through the drainage passages into the back of the nose and throat, from where it is swallowed. This happens continually, although we are usually unaware of it. When excess fluid is produced it is often known as phlegm, or catarrh. It can produce a chronic irritation in the throat known by the unglamorous name of post-nasal drip.
There are 2 main causes of excess mucus production: infection and allergy.
Because the drainage holes from the sinuses are narrow they block up easily. When this happens, pressure builds up in the sinuses causing symptoms which can vary from a mild feeling of congestion, as in a typical head cold, to severe pain. A sensation of partial deafness or blockage in the ear may also occur. This is because the Eustachian tube, which connects the middle ear to the back of the nose, blocks up in just the same way as the nearby sinus openings.
Infections can vary from mild viral illnesses to more severe bacterial infections. In these cases the mucus becomes thick and usually green or yellow in colour. Treatment with antibiotics is often necessary. Spreading into nearby structures, such as the eye or brain, is a serious but rare complication of untreated sinus infections.
Allergic reactions such as hay fever are most common in spring time when allergy-producing pollens are abundant, but can happen at any time in response to a variety of things, including house dust and animals.
For those with recurring sinus congestion and infections, various treatments are available. Sometimes surgery is necessary to drain a blocked sinus, or to enlarge the drainage passage. This is most commonly done using an endoscope (a thin, flexible tube with an attached light), which is passed through the nose. Those with allergies can be helped with nasal spays which suppress the allergic reactions. The use of antihistamine tablets, especially the newer ones with little or no sedating side effects, can be helpful. Saline nasal sprays are also useful in relieving nasal congestion.
If you get a blocked up feeling in the head, simple remedies such as aspirin or paracetamol and steam inhalations may be all you need. But if you develop pain in the face or head, or find you are producing discoloured phlegm, seek medical advice.
Last Reviewed: 30 September 2009