A large new study has raised concerns about the safety of one of the world’s most commonly prescribed antibiotics.
Researchers found that people who took azithromycin had a higher risk of death, including deaths related to heart problems, during the first few days after starting the medication.
The study was led by Dr. Jonathan G. Zaroff and colleagues from Kaiser Permanente Northern California and was published in JAMA Network Open. The findings add to a growing body of research suggesting that azithromycin may affect the heart in ways that could increase the risk of serious complications in some patients.
Azithromycin is a widely used antibiotic that belongs to a group of drugs known as macrolides. Doctors often prescribe it to treat bacterial infections such as bronchitis, pneumonia, sinus infections, ear infections, and some skin infections.
It has become popular because treatment courses are usually shorter than those of many other antibiotics, making it convenient for patients.
For years, scientists have debated whether azithromycin increases the risk of heart problems. Earlier studies produced mixed results.
Some suggested the drug could increase the risk of dangerous heart rhythm disturbances, while others found little or no increased risk. Because of these conflicting findings, researchers wanted to take a closer look using a much larger group of patients.
In the new study, the researchers analyzed medical records from two large healthcare systems in the United States. They examined more than 7.8 million antibiotic prescriptions given to nearly 3 million people.
About 22% of the prescriptions were for azithromycin, while the remaining prescriptions were for amoxicillin, another commonly prescribed antibiotic that was used as a comparison.
The researchers tracked what happened to patients after they started taking the medications. They specifically looked for deaths caused by heart-related conditions, deaths from other causes, and deaths from any cause during the days immediately following treatment.
The results showed a notable difference between the two antibiotics. Within the first five days after starting treatment, people taking azithromycin had an 82% higher risk of dying from heart-related causes compared with people taking amoxicillin. Interestingly, the increased risk was limited to this early period and was not observed after the first five days.
The researchers also found something unexpected. Although azithromycin was not significantly associated with sudden cardiac death in this analysis, people taking the drug still faced a higher overall risk of death.
During the first five days of treatment, they had more than twice the risk of dying from causes not related to the heart and about double the risk of dying from any cause compared with people taking amoxicillin.
The increased risk was also seen among people who already had a higher likelihood of developing cardiovascular disease. This suggests that the findings may be particularly important for patients with existing heart conditions or other risk factors.
Understanding why this increased risk occurs remains challenging. Previous research has suggested that azithromycin can sometimes affect the electrical activity of the heart.
In rare cases, this can lead to abnormal heart rhythms, including a condition called QT prolongation. QT prolongation can occasionally trigger serious and potentially life-threatening arrhythmias.
However, the current study did not find strong evidence linking azithromycin directly to sudden cardiac death. This means there may be additional factors involved that are not yet fully understood. Researchers emphasize that more studies are needed to clarify exactly how the drug might contribute to the increased mortality risk observed in this analysis.
It is important to understand that this type of study cannot prove that azithromycin directly caused the deaths. The research shows an association, meaning the two were linked, but it cannot rule out the possibility that other factors played a role.
For example, patients prescribed azithromycin may have had different underlying illnesses or health conditions than those prescribed amoxicillin.
Even so, the large size of the study makes the findings difficult to ignore. With millions of prescriptions examined, the results suggest that doctors should carefully consider the potential risks and benefits before prescribing azithromycin, particularly for people with existing cardiovascular disease or other serious medical conditions.
The researchers also noted that two of the study authors had financial relationships with the pharmaceutical industry.
In addition, the research received funding from Pfizer, the company that manufactures azithromycin. While these connections do not automatically mean the findings are biased, transparency about potential conflicts of interest is important when evaluating scientific research.
For patients, the study should not be a reason to stop taking prescribed antibiotics without medical advice.
Untreated bacterial infections can also be dangerous and sometimes life-threatening. Instead, the findings highlight the importance of discussing medications with healthcare providers and ensuring that the most appropriate treatment is chosen for each individual’s health situation.
As researchers continue to investigate the safety of commonly used medications, studies like this help doctors make more informed decisions. Although azithromycin remains an important tool for treating bacterial infections, this new evidence suggests that extra caution may be warranted, especially during the first few days after treatment begins.
The study was published in JAMA Network Open.
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