The AMAZES Study research team is aiming to determine whether taking an antibiotic (Azithromycin) alongside normal asthma medications helps to reduce the number of asthma ‘attacks’ and general daily symptoms experienced by adults with asthma. Eligible participants will be randomly allocated to take either Azithromycin or placebo tablets over a 48-week period (neither participants nor investigators will know which medication is being taken until the end of the study). Participants will have their asthma closely monitored over the 48-week period and monitoring will continue for an additional 4 weeks after the treatment has ended. Participants will not need to stop taking their regular asthma medication.

• Adults with asthma (aged 18 and over)
• who are non-smokers (or ex smokers) and
• who experience symptoms despite taking regular preventer medication