A healthy man in his 50s suffered a stroke after drinking eight energy drinks every day — a habit that pushed his blood pressure into a dangerously high range. The incident, described in BMJ Case Reports, is prompting renewed concern about how extreme caffeine intake may strain the cardiovascular system.
The patient arrived at the hospital with sudden weakness, numbness, and trouble walking and speaking. Scans revealed a stroke in the thalamus, the deep brain region involved in movement and sensory processing. His blood pressure measured 254/150 mm Hg — a level so high that clinicians initially struggled to pinpoint the cause. Only after revisiting his daily routine did the source become clear: eight energy drinks every day, adding up to nearly 1,300 milligrams (mg) of caffeine.
“The year 2018 saw major U.K. supermarkets implement a voluntary ban on sales of [these drinks] to under 16s in a drive to tackle obesity, diabetes, and tooth decay, but less explored are the possible increased risks of [energy drinks] for cardiovascular disease, including ischaemic [restricted blood supply or blood clot] and haemorrhagic [bleed in the brain] strokes, particularly in younger demographics otherwise expected to have lower stroke risk,” the study authors said in a press release.
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High-Caffeine Drinks
Energy drinks have grown into a global industry built on images of stamina, speed, and productivity. But the marketing often obscures just how strong the beverages can be. A single can may list its caffeine content, yet the amount varies greatly between brands and can be far higher than most consumers expect.
“The average [energy drink] is said to contain around 80 mg of caffeine per 250 ml serving, compared with 30 mg in tea and 90 mg in coffee, but in some cases can contain up to 500 mg in a single serving,” the authors said. For comparison, health guidelines recommend that adults consume no more than 400 milligrams of caffeine per day.
A drink that appears comparable to a cup or two of coffee may therefore deliver much more stimulation. And for people who consume several servings a day, total caffeine intake can climb into ranges considered unsafe.
Additives and Cardiovascular Strain
Once the man revealed his daily energy drink habit, doctors re-evaluated why his blood pressure had remained so difficult to control. Despite intensive treatment, it stayed dangerously high until he stopped consuming the drinks entirely — after which his blood pressure normalized, and medication was no longer needed. The authors say this pattern points strongly to his daily stimulant intake as the source of the persistent elevation.
The report also notes that energy drinks can exert cardiovascular effects beyond their labeled caffeine amounts. Some ingredients contribute additional “hidden caffeine,” particularly guarana, while others may amplify caffeine’s impact.
“The hypothesis is that the interaction of these other ingredients, including taurine, guarana, ginseng, and glucuronolactone, potentiates the effects of caffeine, heightening stroke [cardiovascular disease] risk through numerous mechanisms,” the authors explained.
Warnings About Long-Term Effects of Energy Drinks
Although his blood pressure eventually recovered, the neurological damage did not. Eight years after the event, the man continues to experience numbness on his left side — a lasting reminder of how quickly a cerebrovascular injury can outpace the body’s ability to heal, even once the underlying trigger has been removed.
The authors note that this single case cannot establish causation, but it adds to growing concern about the cardiovascular strain linked to heavy energy drink use. Given the popularity of these beverages, especially among younger people, they argue that clearer guidance and stronger oversight may help prevent similar cases in the future.
This article is not offering medical advice and should be used for informational purposes only.
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