Duolin Inhaler 70MCG is a combination of two medicine, use for Asthma Treatment. Inhaler Duolin This Inhaler helps relax the muscles of the air passages and making it easier for you to breathe. Always shake this inhaler before using it. place this inhaler on the mouth opening and press down on the inhaler one time to release medicine. After it holds on to your breath for 10 seconds. Repeat the same procedure and inhale the advised number of puffs. Afterward, rinse your mouth with water and spit it out.