Study: No Z-Pak Heart Risk for Most Adults

A common antibiotic does not increase the risk of heart-related death for young and middle-aged adults without heart problems, a new study finds. Earlier research found an increased risk among people with heart disease who took azithromycin. This drug is also known by the brand names Zithromax or Z-Pak. The new study looked at 1.1 million people who took azithromycin for infections. They were compared with 1.1 million who did not take antibiotics and 7 million who took penicillin V. Patients were ages 18 through 64. People were 3 times as likely to die of heart disease or stroke while taking either antibiotic. Death rates were similar for both drugs. Researchers said the higher risk appeared to be related to the infection rather than to the treatment. The U.S. label for azithromycin and antibiotics similar to it carries a warning. It says they could increase the risk of a heart rhythm problem that can lead to death. The warning says this is more likely in people with existing heart problems. The New England Journal of Medicine published the study. HealthDay News wrote about it May 1.

By Robert H. Shmerling, M.D.
Harvard Medical School

What Is the Doctor's Reaction?

Did you ever take a "Z-Pak"? It's a common and convenient antibiotic treatment. The drug is most commonly prescribed for respiratory infections.

Z-Paks contain azithromycin. The brand name is Zithromax, which is where the "Z" comes from. This is an antibiotic in the same family as erythromycin. In recent years, you may have seen news stories suggesting that taking azithromycin comes with a serious risk: sudden cardiac (heart-related) death.

It's true. A study published last year found a small but real increased risk of sudden cardiac death among those taking azithromycin. They were compared with people taking a penicillin-type antibiotic.

But before you swear off azithromycin forever, consider this: The study analyzed adults insured by Medicaid. That's important because this population includes people who tend to have multiple medical problems (including heart disease) and a high death rate in the first place.

What about people whose hearts are healthy? Does the risk of sudden death after taking azithromycin apply to them as well? That's where a new study comes in.

The New England Journal of Medicine published the new study. Researchers looked at the rate of heart- and stroke-related death among more than a million people from the general population who took azithromycin. Their ages were 18 through 64. They were compared with a similar number who took no antibiotic. Azithromycin users also were compared with more than 7 million people who took penicillin.

The results were reassuring:

• The risk of heart- and stroke-related death among people taking azithromycin was similar to that among people taking penicillin.
• Compared with people taking no antibiotic, the risk of heart- and stroke-related death was nearly 3 times higher among people taking azithromycin. However, after statistical analysis, this increase appeared to be related to the infection or other health problems. It was not linked with the antibiotic.
• The number of heart- and stroke-related deaths occurring during azithromycin use in this study was quite low. The researchers estimate that, at most, 11 extra deaths might occur for every 1 million courses of treatment.

This study should provide a measure of comfort to the average person who gets a prescription for azithromycin.

Of course, no medicine is completely risk-free. Allergic reactions and side effects (such as diarrhea) are relatively common with azithromycin use. People with heart problems might be better off taking a different antibiotic, if they need one. Still, this new study suggests that azithromycin seems to be safe for the heart for most people.

What Changes Can I Make Now?

Azithromycin can cause serious side effects. That risk is quite small, but it serves as yet another reminder that we should take antibiotics only when we truly need them. Remember that respiratory infections are often caused by viruses, not bacteria. This is especially likely for infections that cause sore throats, runny nose or cough. Antibiotics don't kill viruses.

If you have heart disease, think twice before taking azithromycin. If your doctor prescribes it, ask whether you're at increased risk for heart rhythm problems. The doctor may decide to prescribe a different antibiotic.

But, if you don't have heart problems, azithromycin is probably as safe as (or even safer than) other antibiotics.

Perhaps the most important changes to make are those that lower your risk of respiratory infection. That means there's less chance you would even need azithromycin in the first place. For example:

• Avoid contact with people who are sick.
• Wash your hands often, especially if you're around someone with an infection. Remind infected people to wash their hands as well and to cover the nose and mouth when coughing or sneezing.
• Don't smoke.
• Get the flu shot each year. You'll be less likely to get the flu. That also means you'll reduce your chances of receiving an antibiotic. Sometimes that happens if there's concern that a bacterial infection might be causing your flu symptoms.
• Get the pneumococcus vaccination (often called "the pneumonia vaccine").

What Can I Expect Looking to the Future?

In the future, we are likely to have new antibiotics. Then we won't need to rely on azithromycin as much as we do now. New antibiotics are likely to have side effects of their own. But I hope that sudden cardiac death won't be among them!

More research should provide a better understanding of who is at risk of heart and blood vessel problems while taking azithromycin. Fortunately, it appears the average young or middle-aged adult is not among them.