Symbicort (budesonide / formoterol) is a combination inhaler used to treat asthma and chronic obstructive pulmonary disease (COPD). It contains two medications: budesonide, a steroid, and formoterol, a long-acting beta-agonist (LABA). Both medications work together to reduce inflammation in the lungs and open up your airways. The typical dose is two puffs by mouth twice a day, usually about 12 hours apart. Common side effects include common cold symptoms, headache, and sore throat.