Seretide Evohaler contains two medicines, salmeterol and fluticasone propionate. Seretide Evohaler is a preventer inhaler and helps to stop asthma symptoms from developing. Seretide Evohaler should not be used to relieve a sudden attack of breathlessness or wheezing. If this happens you need to use a fast-acting ‘reliever’ inhaler, such as salbutamol.