Antibiotics have saved millions of lives by helping the body fight bacterial infections. Doctors prescribe them every day for common illnesses such as chest infections, sinus infections, and pneumonia.
One of the most widely used antibiotics is azithromycin. It is popular because it often requires fewer doses and a shorter treatment period than many other antibiotics. For many patients, this makes the medicine simple and convenient to take.
However, new research is raising concerns that this commonly used drug may not be as harmless as previously believed.
A large study led by Dr. Jonathan G. Zaroff and researchers from Kaiser Permanente in Northern California found that people taking azithromycin had a higher risk of dying shortly after starting the medicine.
The research was published in JAMA Network Open. The findings suggest that the increased risk was especially noticeable for deaths related to the heart and appeared mainly during the first few days after treatment began.
The research team examined information from two large healthcare systems in the United States. They looked at more than 7.8 million antibiotic prescriptions given to nearly 3 million people.
About 22 percent of these prescriptions were for azithromycin, while the remaining prescriptions were for another commonly prescribed antibiotic called amoxicillin. Amoxicillin was used as a comparison because it is also frequently prescribed for infections but is not known to have the same concerns about heart rhythm problems.
The researchers compared the health outcomes of people who took azithromycin with those who took amoxicillin. They focused on deaths that occurred within days of starting treatment. The results were concerning.
Within the first five days after beginning azithromycin, people had an 82 percent higher risk of dying from heart-related causes compared with those who took amoxicillin. Interestingly, the higher risk was no longer seen after those first five days.
The study also found other worrying patterns. People taking azithromycin had more than twice the risk of dying from causes unrelated to the heart and about double the risk of dying from any cause during those first few days of treatment. The researchers saw similar results in people who were already considered at high risk of heart disease.
Previous studies have suggested that azithromycin may affect the electrical activity of the heart in some people. The heart depends on carefully timed electrical signals to beat properly. If these signals are disrupted, dangerous changes in heart rhythm can sometimes occur.
However, in this new study, the researchers did not find a clear link between azithromycin and sudden cardiac death. Even so, the overall increase in deaths was significant enough to raise concerns.
It is important to understand that this study does not prove that azithromycin directly caused these deaths. Studies that examine medical records can identify links between a medicine and health outcomes, but they cannot fully explain why those outcomes occurred.
There may be other factors that also contributed to the findings. Still, the large number of people included in the research makes the results difficult to ignore.
The researchers said doctors should carefully think about the possible risks and benefits before prescribing azithromycin, especially for people who already have heart disease or other serious medical conditions. Patients should not stop taking antibiotics or avoid treatment because of this study.
Untreated bacterial infections can also be dangerous and sometimes life-threatening. Instead, patients should talk openly with their healthcare providers about their medical history and any concerns they have about medications.
The study also noted that two researchers had financial relationships with the pharmaceutical industry and that the research received funding from Pfizer, the company that manufactures azithromycin.
This information does not automatically mean that the findings are biased, but it is useful information for readers to consider when interpreting the study.
The new findings are a reminder that even medicines that have been used for many years can still reveal new risks when researchers continue to study them in large populations. As scientists learn more about how different drugs affect different groups of people, doctors can make better decisions about which treatments are safest and most appropriate for each patient.
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