In recent years, energy drinks have evolved from being seen merely as a “quick stimulant” to products marketed as part of an active and safe lifestyle, particularly among young people and teenagers. However, medical reports and scientific studies continue to raise alarms about excessive consumption, highlighting potential links to high blood pressure, heart rhythm disorders, and even neurological complications in certain populations.

On December 9, BMJ Case Reports published a medical report detailing the case of a 50-year-old man who suffered a severe stroke despite having no traditional risk factors. After a series of tests ruled out possible causes of secondary hypertension, no abnormalities were detected.

However, the patient’s blood pressure was extremely high upon admission. It partially decreased during his hospital stay but rose again after discharge and remained elevated despite treatment with five different antihypertensive medications.

The pivotal moment came when, after more detailed questioning, the patient revealed that he had been consuming an average of eight cans of energy drinks daily for years, each containing 160 mg of caffeine. After he stopped this consumption, his blood pressure returned to normal, allowing doctors to successfully discontinue his antihypertensive medications.

Between warning and exaggeration
Annahar interviewed Dr. Martha Coyle, one of the physicians involved in preparing the report, who emphasized that the study “does not conclusively prove” a direct causal link between energy drinks and the stroke. She explained that her team highlighted this limitation because, by nature, a case study cannot be used to draw broad scientific generalizations.

She added that the possibility of energy drinks playing a role “emerged after all other explanations were ruled out through testing,” noting that “high blood pressure disappeared after stopping their intake.” She described this as evidence suggesting a potential causal link, though not definitive proof.

She continued, “Our primary goal in documenting this case is to raise awareness of the issue, encouraging further research and trials to determine whether a direct causal relationship exists.”
 

Are eight cans an "exception"?
Coyle states that doctors rarely ask patients about energy drinks, making it very difficult to establish safe limits like with alcohol, due to a lack of sufficient studies. However, she described drinking eight cans daily as an "exceptional amount."

Regarding the danger threshold, she explained that it depends on the patient’s age, overall health, and other individual factors, making it difficult to establish a fixed safe limit for energy drinks. However, guidance can be drawn from known caffeine and sugar limits and applied to energy drinks based on their content, while keeping in mind that coffee and energy drinks differ in concentration, serving size, and consumption frequency, and that individuals vary in their sensitivity to caffeine.

According to international guidelines, most healthy adults can safely consume up to 400 mg of caffeine per day - roughly the equivalent of four cups of brewed coffee, though caffeine content varies by type and serving size. For pregnant and breastfeeding women, both the American College of Obstetricians and Gynecologists and the European Food Safety Authority recommend limiting total daily caffeine intake to no more than 200 mg from all sources.

A "small" energy drink can does not differ much from a standard cup of coffee in caffeine content; brewed coffee (237 ml) typically contains about 96 mg, while an energy drink of the same size averages around 79 mg. The difference becomes more significant with larger servings or “energy shots,” which can contain up to 200 mg, especially when consumed frequently throughout the day.

What do previous studies say?

Previous studies suggest that consuming large amounts of energy drinks can raise blood pressure for several hours and may also cause changes in the heart’s electrical activity, as seen on electrocardiograms. Scientific reviews confirm these short-term effects on the heart and blood vessels, particularly in teenagers. Data from poison control centers also show a rise in reports of children exposed to high-caffeine products, highlighting both easy access and the risk of overconsumption.

Dr. Coyle connects the potential risks highlighted in scientific studies with the ease of access to these products, warning that selling them to very young children could lead to excessive consumption among school-aged kids. She urges doctors to include questions about caffeine and energy drink intake in medical histories - “just as we do with smoking, alcohol, and diet” - particularly when symptoms arise that seem inconsistent with a patient’s age or medical background.
 

She concluded her remarks to Annahar by noting that energy drinks are often “widely assumed to be safe” or simply a way to stay awake, but they “could be subtly dangerous.” She emphasized that the issue does not warrant panic, but rather calls for greater public awareness and more in-depth scientific research into their risks and safe consumption limits.