Medications can sometimes cause unexpected side effects, including a cough. This cough can range from mild irritation to a persistent, bothersome symptom. Recognizing a medication as the cause of a new or worsening cough is important for managing your health. This article explores common drug classes associated with cough, its mechanisms, and appropriate steps to address it.
Medication Classes Known to Induce Cough
Angiotensin-converting enzyme (ACE) inhibitors are a well-known class of medications for inducing cough. These drugs are commonly prescribed for high blood pressure and heart failure. The cough caused by ACE inhibitors is typically dry, non-productive, and described as a tickling or scratching sensation. It can be persistent, interfering with daily activities or sleep.
The incidence of ACE inhibitor-induced cough varies, affecting approximately 4% to 35% of patients. This cough can appear within hours of starting the medication or develop weeks to even months later. Examples of ACE inhibitors include lisinopril, enalapril, ramipril, and captopril. Women and non-smokers may have a higher likelihood of experiencing this side effect.
Beyond ACE inhibitors, other medication classes can also lead to a cough, though less commonly. Certain beta-blockers, particularly non-selective types, can induce bronchoconstriction, which may trigger a cough, especially in individuals with underlying respiratory conditions like asthma. Calcium channel blockers, used for heart conditions and hypertension, may indirectly cause cough, possibly by relaxing esophageal muscles, which can lead to acid reflux and subsequent cough.
Inhaled medications, such as some steroid nasal sprays and certain asthma inhalers, can also cause localized irritation and cough. This can be due to the drug itself, the propellant, or the medication delivery method, causing particles to deposit in the upper airways. Statins, used for high cholesterol, have also been reported to cause cough, though the exact reason is not fully understood.
How Medications Trigger Cough
The primary mechanism for ACE inhibitor-induced cough involves the accumulation of natural substances. Angiotensin-converting enzyme, which these drugs inhibit, normally breaks down inflammatory peptides like bradykinin and substance P. When ACE is blocked, levels of bradykinin and substance P increase in the respiratory tract.
This elevation of bradykinin and substance P can sensitize nerve fibers in the airways, leading to an exaggerated cough reflex. Bradykinin may also stimulate prostaglandin production, contributing to airway irritation and cough. While this is the most widely accepted theory, it remains unclear why not all individuals taking ACE inhibitors develop a cough, suggesting other contributing factors or individual sensitivities.
For other medications, different mechanisms may be at play. Beta-blockers can cause cough by blocking beta-2 receptors in the airways, leading to bronchial smooth muscle constriction, especially in susceptible individuals. Inhaled medications can trigger a cough through direct irritation of the throat and airways, or by stimulating cough receptors due to particle size, pH, or aerosol tonicity. Some medications might also indirectly induce cough by causing gastroesophageal reflux, where stomach acid irritates the esophagus, triggering a cough.
What to Do About Medication-Induced Cough
If you suspect a medication is causing a new or persistent cough, consult a healthcare professional. Do not self-diagnose or discontinue prescribed medication without medical advice. Your doctor can assess your symptoms, review your medication list, and help determine if a drug is the cause.
A healthcare provider may adjust the dosage or switch to an alternative drug. For instance, if an ACE inhibitor causes a cough, an angiotensin receptor blocker (ARB) might be prescribed as an alternative, as ARBs typically cause less cough. The cough usually resolves within one to four weeks after discontinuing the offending medication, though full resolution can take up to three months.
Your doctor will also rule out other potential causes for your cough, as many conditions can present with similar symptoms. They may monitor your condition closely after any medication changes to ensure the cough improves and your underlying health condition remains well-managed. The goal is to manage your health effectively while minimizing bothersome side effects.