A commonly prescribed antibiotic that millions of people take each year is being examined more closely after researchers reported a possible increase in the risk of death shortly after treatment begins.
The medicine, azithromycin, is often used to treat chest infections, sinus infections, bronchitis, pneumonia, and other bacterial illnesses because it usually requires only a short course of tablets.
Although it has long been considered convenient and effective, new findings suggest doctors may need to be more careful when deciding who should receive it.
The research was published in JAMA Network Open and was led by Dr. Jonathan G. Zaroff and colleagues from Kaiser Permanente Northern California.
The team wanted to better understand whether azithromycin was linked to a greater chance of dying compared with another commonly prescribed antibiotic, amoxicillin.
To answer this question, the researchers analysed information from two large healthcare systems. They reviewed more than 7.8 million antibiotic prescriptions given to almost 3 million people.
Around one in five prescriptions were for azithromycin, while the remaining prescriptions were mainly for amoxicillin, allowing the researchers to compare the outcomes between the two groups.
The scientists focused on deaths that happened within the first few days after people started taking the antibiotics. They found that during the first five days, people taking azithromycin had an 82% higher risk of dying from heart-related causes than people taking amoxicillin. After those first five days, this extra risk was no longer seen.
The researchers also found other worrying results. People taking azithromycin had more than twice the risk of dying from causes that were not related to the heart and about double the risk of dying from any cause during the same five-day period. Similar patterns were found among people who already had a higher risk of heart disease.
Interestingly, the study did not find a clear increase in sudden cardiac death. Even so, the higher rates of heart-related deaths and overall deaths suggest there may be important effects that need further investigation. The study cannot explain exactly why these differences occurred.
It is important to remember that this was an observational study. This type of research can identify links between a medicine and health outcomes, but it cannot prove that the medicine directly caused the deaths. Other health conditions, the severity of infections, or factors that were not measured may also have influenced the results.
The researchers said doctors should weigh the possible benefits and risks before prescribing azithromycin, especially for people with existing heart disease or other serious medical problems.
Patients should not stop taking antibiotics on their own because untreated bacterial infections can also be dangerous. Anyone with concerns about their medicine should discuss them with their doctor or pharmacist.
The study also noted that two of the researchers had financial relationships with the pharmaceutical industry and that the research received funding from Pfizer, the company that manufactures azithromycin. Declaring these connections is standard practice and allows readers to consider them when interpreting the findings.
Overall, the study adds to growing evidence that commonly used medicines can sometimes have unexpected risks.
More research is needed to confirm these findings, identify which patients are most vulnerable, and help doctors choose the safest antibiotic for each individual situation.
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