Allergies and asthma are indications that your body has increased its production of histamine, a neurotransmitter that regulates water metabolism. This is why antihistamines, drugs that block this effect, are used to dry up the watery eyes and runny noses of allergies and colds.
Apart from interfering with the body's attempts to correct dehydration (by releasing histamine), other side-effects of antihistamines include dry mouth, drowsiness, blurred vision, diarrhoea, nausea and difficulty in passing water.
These have been associated with an increased risk of death or near death. According to the Adverse Drug Reaction Bulletin , which devoted an entire issue to asthma, the marked rise in asthma deaths during the 1960s in many countries "coincided with the introduction of high-strength isoprenaline inhalers". When the inhalers were withdrawn, mortality fell to previous levels.
But the problems haven't just been due to non-selective beta2-agonists. In many countries, a renewed rise in asthma deaths occurred in the 1980s, particularly in New Zealand, where one study showed was linked to the popularity of fenoterol, but also theopylline and oral steroids.
Used for asthma control, these pose many more risks than previously thought. Many doctors are turning to steroids as a first port of call after all the bad press for beta2-agonists. But recent studies have shown that inhaled steroids (which were supposed not to pose the usual risks that swallowed ones do) are not as harmless as medicine previously supposed.
And although conventional medical opinion believes that asthma should be easily controlled with much smaller doses of inhaled steroids, by combining the steroid with a long-acting inhaled bronchodilator, such as formoterol (Foradil), or salbuterol, this isn't ideal either.
The consensus up till now has been that beclomethasone dipropionate (BDP) at 400-800 mcg daily is appropriate for three- to five-year-olds..
Inhaled steroids have also caused symptoms characteristic of Cushing's syndrome: obesity, moon face, thinning skin and stretch marks, as well as bruising.
The use of inhaled steroids for long-term treatment of asthma may lead to reduced bone density in premenopausal women.
Physicians need to work harder to find the minimum dose required to provide asthma control, and make sure that patients maintain adequate dietary calcium and vitamin D intake, say the researchers. In addition, patients who must stay on high doses should be monitored regularly.