Catarrh is an excessive build-up of thick phlegm or mucus in an airway or cavity of the body.
It is usually found in the sinuses (the two small, air-filled cavities either side of your nose), but it can also occur in the throat, ears or chest.
Catarrh is not a condition itself, it is a symptom of a condition such as:
What causes catarrh?
Catarrh is caused by the immune system reacting to an infection or irritation. The immune system is the body's natural defence against infection and illness.
Your immune system sends infection-fighting white blood cells to the source of the infection or irritation. These release molecules called inflammatory mediators which cause the mucous membranes to swell and produce mucus. The swelling also narrows the cavity, resulting in further congestion.
Read more about the causes of catarrh.
Should I see my GP?
In most cases, catarrh will usually clear up as the underlying infection only lasts a short period of time.
If your catarrh persists, speak to your GP. They may want to rule out conditions such as nasal polyps and find if your catarrh is being caused by an allergic reaction.
Read more about diagnosing chronic catarrh.
If your catarrh hasn't cleared up on its own your treatment will depend on the underlying cause.
Decongestant medicines can help relieve a blocked nose by reducing swelling of the blood vessels in your nose. Decongestants are available from pharmacies without a prescription.
Steam inhalation may also help.
Read more about how catarrh is treated.
Causes of catarrh
Catarrh is caused by the immune system reacting to an infection or irritation in an airway or a cavity of the body, such as inside the nose.
Your immune system sends infection-fighting white blood cells to the source of the infection.
The white blood cells cause the mucous membrane that lines the affected area to swell and produce mucus. The swelling will also narrow the cavity, resulting in further congestion.
The most common triggers of catarrh are:
Some people have abnormally sensitive blood vessels that react to environmental triggers, such as cigarette smoke and pollution. The reasons for this over-sensitivity are unknown.
The affected blood vessels become enlarged (swollen) in a similar way to how they respond to an infection or allergic reaction. The swelling leads to congestion and catarrh.
As well as cigarette smoke and pollution, other triggers of non-allergic rhinitis include:
Read more about non-allergic rhinitis.
Nasal polyps are non-cancerous, fleshy swellings that grow from the lining of your nose or your sinuses (the small cavities inside your nose).
The polyps can prevent mucus from properly draining out of your nose or sinuses, leading to congestion and catarrh.
Read more about nasal polyps.
Diagnosing the causes of catarrh
In most cases, catarrh does not need to be diagnosed because the underlying infection will pass quickly, often without treatment.
Further investigation will be required in cases where catarrh persists for longer (chronic catarrh).
Your GP may examine your nose to check for nasal polyps (fleshy swellings that develop in the lining of the nose that prevent mucus from draining properly).
Your GP may also want to check that your catarrh is not the result of an allergic reaction. You'll be asked whether your symptoms are worse in particular environments or at certain times of the day or year. This will help them to pinpoint a possible allergen (a substance that causes an allergic reaction).
In rare cases, an allergy test may be recommended if an allergic reaction is thought to be causing your catarrh, and the allergen responsible is not known. This will usually involve having a skin prick test, where allergens are placed on your arm and introduced into your skin by pricking it with a short pin. If you are allergic to the substance, a small welt (itchy spot) will appear.
Read more about diagnosing allergic rhinitis.
Persistent catarrh can also be caused by non-allergic rhinitis. Diagnosing non-allergic rhinitis can be difficult because it shares many of the same symptoms as allergic rhinitis, but there are no specific tests for the condition.
If allergy tests reveal you are not experiencing an allergic reaction, non-allergic rhinitis may then be diagnosed.
Treatment for catarrh is not often necessary because it will disappear within a few days, after your body has fought off the infection.
If treatment is required, the type of treatment recommended will depend on the underlying cause.
To help relieve a blocked nose you can use decongestant medication and steam inhalation
Decongestants help relieve a blocked nose by reducing swelling of blood vessels in your nose.
Decongestants are available in tablet form or as a nasal spray and can be bought from pharmacies without a prescription. Oral decongestants (those taken by mouth) may take a little longer to work, but their effect can last longer than nasal sprays.
You should not use decongestants for more than 5-7 days at a time. This is because they only provide short-term relief and using them for longer than seven days may make your symptoms worse.
Decongestants do not usually cause side effects and, if they do, they are likely to be mild. Possible side effects of decongestant nasal sprays may include:
Read more about decongestant medicines.
Inhaling steam from a bowl of hot (but not boiling) water may help soften and loosen up the mucus in your nasal cavities.
Adding menthol crystals or eucalyptus oil to the water may also help to ease your blocked nose.
Steam inhalation is not recommended as a suitable treatment for children due to the risk of scalding.
The recommended treatment for persistent catarrh will depend on the underlying cause.
For example, rhinitis can usually be managed by avoiding the allergens (substances responsible for causing allergic reactions) or environmental triggers that cause catarrh.
It may be possible to relieve persistent catarrh by using a nasal spray that contains corticosteroids (medication that helps reduce inflammation).
If you have small nasal polyps (fleshy growths in your nose) it may be possible to shrink them using a nasal spray containing steroids. Surgery may be needed to remove larger nasal polyps.
Read more about treating nasal polyps.
Symptoms associated with catarrh
Symptoms often associated with catarrh include: