A stable dry powder composition for inhalation includes acetylsalicylic acid in particles having a mass median aerodynamic diameter (MMAD) in a range of about 1 μm to about 5 μm. The dry powder composition may contain a pharmaceutically acceptable excipient, such as a stearate, in an amount ranging from about 0.04% (w/w) to about 0.06% (w/w), or from about 0.4% (w/w) to about 0.6% (w/w), of the composition.