An aerosol solution composition for use in an aerosol inhaler comprises an active material, a propellant containing a hydrofluoroalkane, a cosolvent and optionally a low volatility component to increase the mass median aerodynamic diameter (MMAD) of the aerosol particles on actuation of the inhaler. The composition is stabilized by using a small amount of mineral acid and a suitable can having part or all of its internal matellic surfaces made of stainless steel, anodized aluminium or lines with an inert organic coating.
