Symbicort dosage. Inhalers deliver two different strengths Symbicort: 160 micrograms (mcg) of budesonide/4.5 mcg formoterol and 80 mcg budesonide/4.5 mcg formoterol. Regardless of the strength, each inhaler contains 4.5 of formoterol, while the dose of budesonide varies. Your doctor will determine what dose and strength is best for you. You may begin with a lower dose of Symbicort and adjust the dose with your doctor’s supervision over a period of several weeks until your symptoms are controlled.