Researchers warn that heavy energy drink intake increases the risk of stroke, according to a study published in BMJ Case Reports. A team from Nottingham University Hospitals NHS Trust, UK, reports on the medical case of a healthy man in his 50s with the habit of drinking eight cans of energy drinks daily, who developed extremely high blood pressure. The authors call for tighter regulation of the sale and advertising of these products.
The man needed medical help after he suffered a stroke in his thalamus (the part of the brain involved in sensory perception and movement). Symptoms included left-sided weakness, numbness, as well as difficulties with balance, walking, swallowing, and speech. At the hospital, his blood pressure was 254/150 mm Hg, which is exceptionally high. He was treated with drugs to lower blood pressure, and his systolic blood pressure eventually dropped to 170 mm Hg. The patient was sent home.
However, at home, his blood pressure increased again and remained high despite continuing his treatment. He then revealed that he drank an average of 8 cans of energy drinks a day, adding up to a daily intake of 1200-1300 mg of caffeine. The recommended maximum daily intake is 400 mg. He was advised to stop drinking these energy drinks, after which his blood pressure returned to normal.
However, there were some long-lasting consequences. “I obviously wasn’t aware of the dangers drinking energy drinks was causing to myself. (I) have been left with numbness (in my) left hand side hand and fingers, foot and toes even after 8 years,” he said.
This lack of awareness about the potential cardiovascular risks associated with heavy energy drink consumption is not surprising, given that they aren’t generally seen as a potential cardiovascular disease risk.
“The year 2018 saw major UK 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,” they emphasise.
The problem is that it is not always easy to determine the caffeine content of these drinks. In terms of pure caffeine, energy drinks contain around 80 mg per 250 ml serving, compared with 30 mg in tea and 90 mg in coffee, but can contain up to 500 mg per serving.
However, “this declared amount is the ‘pure caffeine’, but other ingredients contain ‘hidden caffeine’— for example, guarana is thought to contain caffeine at twice the concentration of a coffee bean,” explained the authors. “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.”
This is just one patient, warn that “while the current evidence is not conclusive, given the accumulating literature, the high morbidity and mortality associated with stroke and [cardiovascular disease] and the well-documented adverse health effects of high-sugar drinks, we propose that increased regulation of [energy drink] sales and advertising campaigns (which are often targeted at younger ages) could be beneficial to the future cerebrovascular and cardiovascular health of our society.”
Coyle M, Munshi S Energy drinks, hypertension and stroke BMJ Case Reports CP 2025;18:e267441.