What is bronchitis?
Bronchitis is an inflammation of the bronchial tubes that bring air to the lungs. When irritated, they swell, preventing cilia (tiny hairs) from clearing the passages. Mucus builds up, stimulating a reflex to clear them - a cough. This is the primary symptom of bronchitis (though not all coughs are due to bronchitis).

Acute (short-lived) bronchitis often follows a cold or flu. It produces a ‘burning’ chest and phlegmy cough, perhaps with a sore throat and a temperature. It is usually caused by a virus, rarely bacteria, and is infectious.

Chronic bronchitis is a cough lasting at least three months, two years in a row. There’s often lots of mucus, wheezing and shortness of breath. Mainly due to air pollution (dust or cigarette smoke), it may also result from childhood pneumonia or an untreated illness. It may also lead to emphysema.

What doctors tell you
There are five conventional drug treatments for bronchitis:

* Bronchodilators include beta-agonists that relax the airways, and anticholinergics, which block the chemicals produced by the body to contract the airways. Beta-agonist side-effects, especially in the elderly, include heart problems, tremor and nervousness. The two types of drugs are often combined to reduce the side-effects.

* Epinephrine (adrenaline) is usually given to babies with bronchitis, although it may be no better than a placebo, and causes the heart to race (N Engl J Med, 2003; 349: 27-35).

* Corticosteroids such as prednisone reduce mucus and inflammation, but side-effects can be considerable (skin damage, cataracts, diabetes, osteoporosis and secondary infections) particularly in the elderly. Combinations of corticosteroids and beta-agonists have been tried, but the evidence for their effectiveness is weak (Cochrane Data-base Syst Rev, 2003; 4: CD003794).

* Antibiotics may prevent infection, but they do nothing for the underlying condition.

* Over-the-counter cold remedies such as antihistamines and decongestants may exacerbate the problem by thickening the mucus, thereby worsening the coughing.

* Oxygen may be given in extreme cases to aid breathing.

Tony Edwards