What Is an ACE Inhibitor Cough?

Why do ACE inhibitors cause coughs?

The exact cause of an ACE inhibitor cough isn’t fully understood. One theory is that while the intent of these medications is to block the angiotensin-converting enzyme, they might also interfere with other substances in the body, like bradykinin and substance P (SP).

The role of bradykinin in ACE inhibitor coughs

Bradykinin relaxes blood vessels, helps the kidneys remove excess sodium from the body and ultimately lowers blood pressure. But bradykinin plays other roles in the body and is also involved in inflammation.

Normally, the ACE enzyme breaks down this helpful protein. But an ACE inhibitor prevents that from happening so that bradykinin can stick around to help regulate blood pressure. Some doctors theorize that bradykinin may accumulate in the airways and cause a cough.

“It’s unclear why [bradykinin] stimulates this need to cough,” Cox says. “[The protein] may stimulate some of the fibers in the lungs and in the airways that sort of trigger that natural response and almost trick the lungs into thinking they need to cough when they don’t.”

Risk factors

Predicting who might develop an ACE inhibitor cough isn’t easy for doctors. Typically, the most significant risk factor is having had one in the past.

Despite research into genetic predispositions, doctors are unable to foresee why some end up with an ACE inhibitor cough, says Cox.

How to treat ACE inhibitor coughs

Often it’s recommended that patients who have an ACE inhibitor cough switch to an alternative class of drugs, since, Cox says, about two-thirds of patients who try another ACE inhibitor will experience a recurrence of the cough.

“I always tell people, ‘Yes, this is annoying and we’re sorry that this happened to you,’” Cox says. “But the good news is … that we have lots of other options that we can either treat your high blood pressure or whatever else was being treated.”

It’s crucial never to discontinue your ACE inhibitor without consulting your doctor, especially since stopping the medication abruptly can worsen certain conditions and exacerbate underlying diseases.

ACE inhibitor cough, BHR and asthma

If you have asthma or bronchial hyperresponsiveness (BHR), knowing whether your cough is from an ACE inhibitor reaction or is a symptom of your underlying condition is tricky.

“They’re some of the most difficult [cases] because their disease can often manifest as this dry hacking cough,” says Cox. “Is it your asthma, your lung condition or is it the drug?”

Know that if you do experience an ACE inhibitor cough and have a lung issue, the cough from the medication shouldn’t be any more severe than the same cough experienced by someone without a lung condition.

Patients with asthma could undergo a pulmonary function test to assess any changes in lung function, which would not be unrelated to taking an ACE inhibitor.

Otherwise, Cox suggests switching to a different class of medications because there are plenty of other effective and affordable options available.

ACE inhibitor alternatives

One of the most common alternatives prescribed when patients experience a cough after starting ACE inhibitor treatment is an angiotensin receptor blocker. ARBs operate along the same pathway but act differently by blocking the end result instead of directly inhibiting the ACE enzyme.

“So you end up sort of doing the same thing, but with much lower risk of cough,” says Cox.

ACE inhibitors are often prescribed first because they were FDA-approved before ARBs, which tended to be more expensive before generic options became available. However, data would suggest you can get the exact same benefit for chronic kidney disease, heart failure and high blood pressure with an ARB. “So there is not a real medical need to try [an ACE inhibitor] first before going to an ARB anymore,” says Cox.