ACE inhibitor cough: switching to an ARB
The case
A 70-year-old man with a 10-year history of hypertension and type 2 diabetes has taken ramipril 10 mg daily for the past 6 months. He presents to his GP with a 3-week history of persistent non-productive cough. He has no dyspnoea, haemoptysis, fever or recent respiratory illness. Blood pressure is 135/80 mmHg, oxygen saturation 98% on room air, and chest examination is normal. Chest X-ray shows clear lung fields and spirometry shows a normal FEV1/FVC ratio. What is the most appropriate next management step?
Options
- ASwitch ramipril to losartan once daily
- BAdd codeine and continue ramipril
- CReduce ramipril to 5 mg once daily
- DStart inhaled budesonide-formoterol
- ERefer for diagnostic bronchoscopy
Think it through before you read on. Which single option is best, and why are the other four wrong?
Show the answer and explanation
Answer
A. Switch ramipril to losartan once daily
Why this is the right answer
This is a typical ACE inhibitor cough. It is dry, persistent and starts weeks to months after the drug is begun. The chest X-ray and spirometry are normal, and there are no features of infection, asthma or heart failure.
ACE inhibitors block the breakdown of bradykinin. Bradykinin builds up in the airway and stimulates cough receptors. This is a class effect and it does not depend on the dose, so lowering the dose does not fix it. It affects around 5–20% of patients and is more common in women and in people of East Asian background.
Angiotensin receptor blockers (ARBs) such as losartan, candesartan or irbesartan act on the angiotensin II receptor and do not affect bradykinin. They give the same blood pressure control and the same kidney protection in diabetes, without the cough. Australian guidance (Heart Foundation hypertension guideline, 2016; Australian Medicines Handbook) supports switching to an ARB when an ACE inhibitor causes cough [VERIFY].
After the switch the cough usually settles within 1 to 4 weeks. If it does not, another cause must be looked for.
Important: an ACE inhibitor and an ARB should not be combined. The switch replaces one with the other.
Why the other options are wrong
- B
Codeine suppresses the symptom, leaves the cause, and adds opioid side effects.
- C
The cough is a class effect and is not dose-related, so halving the dose will not reliably help.
- D
Inhaled corticosteroid-LABA treats asthma or COPD; spirometry here is normal.
- E
Bronchoscopy is for haemoptysis or abnormal imaging, not for a likely drug side effect with a clear chest X-ray.
High-yield takeaway
A dry cough on an ACE inhibitor is dose-independent: stop it and switch to an ARB, never combine the two.
Reference: National Heart Foundation of Australia Guideline for the Diagnosis and Management of Hypertension in Adults (2016)
Common questions
How long does an ACE inhibitor cough take to settle after stopping?
Usually within one to four weeks. If it persists beyond that, look for another cause.
Can an ARB be added instead of swapped?
No. The two are never combined. The ACE inhibitor is stopped and the ARB replaces it.
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