Controller (maintenance) drugs treat the airway inflammation that drives symptoms and exacerbations. They do not relieve an attack in progress; their benefit builds over days to weeks.

Asthma vs. COPD: asthma inflammation is usually steroid-responsive, so ICS is the foundation of asthma treatment. In COPD, ICS helps mainly clients with frequent exacerbations and high blood eosinophils; bronchodilators are the foundation.

Before stepping up any controller: check inhaler technique, adherence, triggers, and comorbidities — most "treatment failures" are device or adherence problems.

• ICS: not for relief of acute bronchospasm; caution with untreated fungal, bacterial, or tuberculosis infection and with herpes simplex of the eye. Strong CYP3A4 inhibitors (ritonavir, cobicistat, ketoconazole) raise fluticasone and budesonide levels and can cause Cushing syndrome and adrenal suppression — beclomethasone or ciclesonide may be preferred.
• Systemic corticosteroids: caution in diabetes, uncontrolled hypertension, heart failure, peptic ulcer, active infection, glaucoma, psychiatric illness, and osteoporosis. NSAIDs add GI bleeding risk; loop/thiazide diuretics and beta₂ agonists add hypokalemia; corticosteroids raise glucose and oppose antidiabetic drugs. Live vaccines are avoided during high-dose therapy (about 20 mg/day of prednisone or more for 14 days or longer).
• Montelukast: avoid or use with great caution in clients with a history of depression or suicidal behavior; for allergic rhinitis alone, the FDA advises reserving it for clients who cannot use other treatments.
• Zafirlukast/zileuton: liver disease; zileuton raises theophylline and warfarin effects; zafirlukast increases warfarin effect.
• Roflumilast: contraindicated in moderate to severe liver impairment; avoid with strong CYP inducers (rifampin, carbamazepine, phenytoin); caution with depression.
• Azithromycin: avoid with QT prolongation, hypokalemia, or other QT-prolonging drugs; baseline hearing and ECG.
• Biologics: not for acute attacks; treat helminth infections before starting; live vaccines are generally avoided during treatment.
• Pregnancy and lactation: continue ICS in pregnancy — poorly controlled asthma harms the fetus more than ICS does; budesonide has the most data. Montelukast and systemic corticosteroids may be used when needed (oral steroids in the first trimester carry a small cleft-lip risk and raise gestational glucose). Roflumilast is not recommended in pregnancy. Biologic data are limited; decisions are specialist-led.

Listed in priority order.

1. Respiratory status and exacerbation risk
   • Assess symptoms, night waking, reliever use, PEF/FEV₁, SpO₂, and exacerbation history at every contact. Increasing reliever use signals loss of control.
   • In COPD clients on ICS, watch for pneumonia (fever, new crackles, purulent sputum).
2. Administration
   • Give the bronchodilator before the ICS when both are scheduled separately.
   • Watch the client use the device; correct technique before any dose increase.
   • Have the client rinse the mouth with water and spit after each ICS dose; use a spacer with ICS pMDIs.
   • Give oral corticosteroids with food, in the morning.
3. Laboratory and physical monitoring
   • Glucose during systemic corticosteroids — report persistent values above about 180 mg/dL (10.0 mmol/L) in hospitalized clients; potassium 3.5–5.0 mEq/L (3.5–5.0 mmol/L); blood pressure, weight, edema, mood and sleep.
   • Long-term high-dose ICS or repeated steroid courses: bone density, eye examinations (cataract, glaucoma), and height in children at each visit.
   • Liver tests with zileuton and zafirlukast; weight with roflumilast.
   • Mood and behavior with montelukast and roflumilast — ask about sleep, nightmares, depression, and suicidal thoughts.
4. Corticosteroid tapering and adrenal suppression
   • Short bursts (5–7 days) usually stop without tapering. Courses longer than about 2–3 weeks, or frequent courses, need a taper and may require stress-dose steroids during surgery or serious illness.
5. Biologics
   • Give in a setting prepared for anaphylaxis (epinephrine available). Observe per product labeling — for omalizumab, commonly 2 hours after the first three injections and 30 minutes after later ones.
   • Check eosinophil count and IgE as ordered; screen for parasite exposure where relevant.

• Controllers prevent attacks — take them every day, even when well. Improvement builds over weeks; do not stop because symptoms are gone.
• ICS-formoterol (Track 1): the same inhaler relieves symptoms; follow the written plan's daily maximum (budesonide-formoterol usually no more than 12 inhalations in one day for adults) and seek care if you need more.
• Rinse and spit after every ICS dose; report white patches in the mouth or hoarseness.
• Oral corticosteroids: take with food in the morning; finish the course; never stop a long course suddenly; report high blood glucose, black stools, mood changes, or signs of infection. People with diabetes check glucose more often.
• Montelukast: take in the evening; family members should watch for and report mood or behavior changes, nightmares, or suicidal thoughts right away.
• Roflumilast: weigh yourself regularly; report ongoing weight loss, depression, or suicidal thoughts.
• Biologics: keep appointments; stay for the observation period; carry an epinephrine auto-injector if prescribed; learn anaphylaxis signs (hives, throat tightness, wheeze, dizziness) that can be delayed.
• COPD on ICS: report fever, increased or colored sputum, or worse breathlessness early.
• Keep a written asthma action plan or COPD action plan and bring all inhalers to every visit.

There is no specific antidote for an ICS or leukotriene modifier overdose; acute overdose is rarely dangerous — the risks come from long-term excess.

• Controllers treat inflammation; they do not stop an acute attack
• Every adult and adolescent with asthma needs ICS-containing treatment; as-needed ICS-formoterol is the preferred reliever (GINA Track 1)
• ICS: rinse and spit — prevents thrush and hoarseness
• COPD: ICS never alone; start triple therapy (LABA + LAMA + ICS) in group E with eosinophils ≥ 300 cells/µL (at follow-up, add ICS for exacerbations when eosinophils are ≥ 100); ICS increases pneumonia risk
• Systemic steroids for exacerbations: asthma 5–7 days, COPD 5 days; monitor glucose, BP, potassium, mood
• Taper long courses; adrenal crisis → IV hydrocortisone
• Montelukast: boxed warning — neuropsychiatric events, including suicidal thinking
• Roflumilast: diarrhea, weight loss, depression; not a rescue drug
• Biologics: observe for anaphylaxis; dupilumab and mepolizumab are now options for eosinophilic COPD
• Continue ICS in pregnancy — uncontrolled asthma is the greater risk
• Ritonavir or cobicistat with fluticasone/budesonide → Cushing syndrome