ACE Inhibitors Are the Blood Pressure Medications That Cause Cough
ACE inhibitors (angiotensin-converting enzyme inhibitors) are the antihypertensive drug class most strongly associated with dry, persistent cough, affecting 5-35% of treated patients. 1
Clinical Characteristics of ACE Inhibitor-Induced Cough
The cough presents with distinctive features:
- Dry, nonproductive with a tickling or scratching throat sensation 1
- Not dose-dependent - changing the dose won't help 1
- Onset timing is variable - can occur within hours of the first dose or be delayed for weeks to months after starting therapy 1
- Class effect - switching to another ACE inhibitor will replicate the cough 1
High-Risk Patient Groups
Cough occurs more frequently in:
- Women 1
- Nonsmokers 1
- Persons of Chinese origin 1
- Patients treated for heart failure (compared to hypertension alone) 1
Mechanism
The cough results from accumulation of bradykinin and substance P (normally degraded by ACE) in the upper respiratory tract, which stimulates prostaglandin production and sensitizes lung C-fiber afferents 1. This explains why it's a class effect - all ACE inhibitors share this mechanism.
Diagnostic Approach
When evaluating chronic cough in any patient on an ACE inhibitor, consider the ACE inhibitor as causative regardless of when the cough started relative to drug initiation. 1
Confirmation Strategy:
- Discontinue the ACE inhibitor - this is the only definitive diagnostic test 1
- Wait for resolution - typically 1-4 weeks, but may take up to 3 months in some patients 1
- Diagnosis is confirmed when cough resolves after stopping the medication
Common pitfall: Don't dismiss ACE inhibitors as the cause just because the patient has been on the medication for months or years without prior cough - onset can be significantly delayed 1.
Management Algorithm
Step 1: Discontinue the ACE Inhibitor
This is the only uniformly effective treatment (Grade B recommendation) 1
Step 2: Switch to an Alternative Agent
Switch to an angiotensin receptor blocker (ARB) - the incidence of cough with ARBs is similar to placebo and significantly lower than ACE inhibitors (Grade A recommendation) 1. Studies with losartan, candesartan, and eprosartan demonstrate cough rates comparable to placebo in patients with prior ACE inhibitor-induced cough 1, 2, 3.
Step 3: If ACE Inhibitor Must Be Continued
If there's a compelling cardiovascular reason to use an ACE inhibitor specifically:
Option A: Attempt re-challenge after cough resolution - a minority of patients will not experience recurrent cough (Grade A recommendation) 1
Option B: Consider switching to perindopril, which has the lowest incidence of cough among ACE inhibitors due to high tissue ACE affinity 4, 5
Option C: Add pharmacologic cough suppressants (Grade B recommendation) 1:
- Sodium cromoglycate
- Theophylline
- NSAIDs (sulindac, indomethacin, aspirin)
- Calcium channel blockers (amlodipine, nifedipine)
- Ferrous sulfate
- Picotamide
These agents have shown variable success in attenuating cough but are not uniformly effective 1.
Key Clinical Pearls
- ARBs do not cause cough - their mechanism bypasses ACE inhibition, avoiding bradykinin accumulation 1
- Don't waste time with dose reduction - cough is not dose-dependent 1
- Be patient with resolution - while most resolve in 1-4 weeks, some patients require up to 3 months 1
- Real-world incidence is lower than clinical trials suggest - don't automatically switch all patients, but investigate if cough is reported 5
The evidence strongly supports that when ACE inhibitor-induced cough is persistent or intolerable, switching to an ARB provides equivalent cardiovascular protection without the cough side effect 1.