Why Do ACE Inhibitors Cause a Cough?
Lisinopril belongs to a class of medications called Angiotensin-Converting Enzyme (ACE) inhibitors. These drugs are prescribed to treat high blood pressure, heart failure, and heart attacks by widening blood vessels to improve blood flow. The primary function of an ACE inhibitor is to block the enzyme that converts angiotensin I into angiotensin II. While this successfully manages blood pressure, it has an unintended consequence that can lead to a cough.
The cough is caused by the accumulation of certain proteins and substances in the airways. When ACE is inhibited, it also prevents the breakdown of bradykinin and substance P. The buildup of these substances can irritate nerve endings in the throat and lungs, triggering a persistent, non-productive cough. It's also been suggested that this process can stimulate the production of prostaglandins, which further sensitize nerve endings and promote coughing.
What Does a Lisinopril Cough Feel Like?
A lisinopril-induced cough has distinct characteristics that differentiate it from other types of coughs. It is typically:
- Dry: The cough is non-productive, meaning it does not bring up mucus or phlegm.
- Persistent: It can be bothersome and does not go away with typical cough remedies.
- Tickly or Scratchy: Patients often describe a tickling or scratchy sensation in the throat that triggers the urge to cough.
- Variable Onset: The cough can begin hours, weeks, or even months after starting the medication.
- Resolves with Discontinuation: The cough typically disappears within a few weeks to a month after stopping lisinopril, although for some, it may linger for up to three months.
How Common is a Lisinopril Cough?
The incidence of a lisinopril-induced cough varies significantly, with reports indicating it can affect anywhere from 5% to 35% of patients. This wide range likely reflects differences in study populations and reporting methods. The cough is not dose-dependent, meaning it can occur regardless of the dosage of lisinopril taken. Some studies suggest the cough is more prevalent in certain groups, including women and individuals of Asian descent.
What to Do If You Develop a Cough?
If you believe lisinopril is causing your cough, it is crucial to consult your doctor. Never stop taking your medication without professional guidance. The most effective management strategy is to discontinue lisinopril and switch to an alternative medication. Your doctor can determine the best course of action. While some over-the-counter cough suppressants or home remedies may provide minor relief, they are not effective in treating this specific type of cough. The cough's underlying mechanism, the accumulation of bradykinin, is not addressed by traditional cough medicines.
Alternative Medications: ARBs
For patients who experience a persistent cough from lisinopril, Angiotensin II Receptor Blockers (ARBs) like losartan or valsartan are a highly recommended alternative. ARBs work on the same system as ACE inhibitors but block the angiotensin II receptor instead of the converting enzyme. This different mechanism avoids the buildup of bradykinin and substance P, leading to a much lower risk of cough. Clinical trials have shown that switching from an ACE inhibitor to an ARB significantly reduces or eliminates the cough.
Comparison: Lisinopril (ACE Inhibitor) vs. ARBs
| Feature | Lisinopril (ACE Inhibitor) | Angiotensin II Receptor Blockers (ARBs) |
|---|---|---|
| Mechanism of Action | Blocks the angiotensin-converting enzyme (ACE). | Blocks the angiotensin II receptor. |
| Effect on Bradykinin | Prevents breakdown, leading to accumulation. | Does not interfere with bradykinin breakdown. |
| Risk of Cough | Relatively common, affecting 5-35% of users. | Significantly lower risk of cough, similar to placebo. |
| Cough Characteristics | Persistent, dry, tickly. | Rare. |
| Management of Cough | Discontinuation of the medication. | Not typically needed, as cough is not a common side effect. |
| Example Drugs | Lisinopril, Captopril, Enalapril. | Losartan, Valsartan, Telmisartan. |
Conclusion
A persistent, dry cough is a notable side effect for many individuals taking lisinopril, but it is a manageable condition. The cough results from the drug's impact on bradykinin levels, which differs from other types of coughs and does not typically respond to conventional cough remedies. If you develop this side effect, it's essential to talk to your healthcare provider to discuss alternative treatment options, such as switching to an Angiotensin II Receptor Blocker (ARB). Discontinuing lisinopril under medical supervision is the most effective way to resolve the cough. Taking this proactive approach ensures your blood pressure remains controlled while addressing this uncomfortable side effect.
For more detailed scientific information on the mechanism of ACE inhibitor-induced cough, you can consult research articles available on reputable medical databases like PubMed, such as the 1990 review on ACE inhibitors and cough.
