AZithromycin Against pLacebo in Exacerbations of Asthma

Acute attacks (exacerbations) of asthma are common and cause a great deal of suffering in asthmatic patients. Current treatments for asthma attacks are not completely effective and new and better treatments are needed. Viruses often cause asthma attacks and bacterial lung infections have also been associated with asthma attacks. However, the role for bacteria is uncertain. Current asthma guidelines for doctors treating asthma exacerbations do not recommend the routine use of antibiotics. The investigators would like to investigate whether or not azithromycin, which is a safe and well tolerated antibiotic (an antibacterial) that has been used for many years in the treatment of respiratory disease, might be of benefit in asthma attacks. As there is some evidence that azithromycin has anti-viral properties this may add to its benefits (antibiotics don't usually affect viruses). By looking at the effect of azithromycin on asthma attacks this will help us to show whether or not azithromycin should be recommended during an acute asthma attack in addition to the usual care that is provided to these patients as it may help them recover quicker from the exacerbation. The investigators will also be able to look at why azithromycin may be effective - if it is having an anti-bacterial and/or anti-viral effect.