GINA step therapy provides a systematic approach to asthma controller escalation and de-escalation. Step 1-2: PRN low-dose ICS-formoterol (preferred) or daily low-dose ICS + SABA PRN. Step 3: low-dose ICS-LABA maintenance (budesonide-formoterol preferred for MART). Step 4: medium-dose ICS-LABA +/- LTRA or tiotropium. Step 5: high-dose ICS-LABA + tiotropium; consider anti-IgE (omalizumab), anti-IL5 (mepolizumab, benralizumab), anti-IL4R (dupilumab), or anti-TSLP (tezepelumab) biologics based on phenotype. The clinician prescribes initial therapy based on severity classification and adjusts every 2-3 months based on symptom control assessment (ACT or ACQ scores). Step-down is attempted after 3 months of well-controlled asthma, reducing ICS dose by 25-50% while monitoring.