Those knocking back multiple cans of energy drinks a day may be risking a toxic overdose, doctors have warned. Surprisingly the danger comes not from sugar or caffeine, but from vitamin B6 – added to boost energy and concentration.
Found naturally in fish, poultry, potatoes and avocados, B6 is essential for brain and nerve health in small amounts.
But over time, excess intake may trigger peripheral neuropathy – a painful and debilitating condition that causes tingling, numbness and burning in the hands and feet. In rare instances it can even affect the heart and circulation.
And the vitamin – often listed as pyridoxine, pyridoxal or pyridoxamine – is present in thousands of products as an additive, ranging from medicines and multivitamin supplements to energy drinks and weight-loss shakes.
But last month, the Australian medicine regulator, the Therapeutic Goods Administration (TGA), reported a surge in vitamin B6 toxicity cases – with 170 confirmed so far, and fears that thousands more may be undiagnosed.
The NHS recommends women consume 1.2mg of vitamin B6 a day, and 1.4mg for men, advising against more than 10mg without medical supervision. Yet a 250ml can of Red Bull contains 4.5mg, while a 500ml can of Monster Energy has around 4mg. Just three cans per day could push intake above the official ‘safe’ limit.
NHS guidance notes that symptoms of toxicity usually appear above 200mg, but admits the risks are ‘unclear’ between 10mg and 200mg.
But the TGA has gone further, warning that nerve damage may occur at less than 50mg a day, while the European Food Safety Authority has also concluded there is enough evidence that intakes of 50mg a day can cause harm in some individuals, and set a much lower tolerable upper daily limit of 12mg.
Professor Alan Boobis, a toxicology expert at Imperial College London, emphasized that it is unlikely that energy drinks or supplements alone would push intake over the threshold.
Instead, he warned the real risk comes from overconsumption. Often without realising, people may be getting vitamin B6 from multiple sources at once. ‘If there is regular use of both over a period of time,’ he said, ‘nerve damage that can lead to peripheral neuropathy may develop’.
And GP Dr Giuseppe Aragona said it is this cumulative effect that ‘catches people out’. He explained: ‘If you add in B6 from multivitamins or fortified foods, it can add up without someone realising.
‘So while an occasional energy drink is unlikely to do harm, drinking multiple cans every day could increase the risk of toxicity, especially over time.’
He added that because the symptoms can ‘overlap with conditions like diabetes, B12 deficiency or nerve problems’, some ‘cases could go unrecognised,’ he warned, adding that it’s plausible that hundreds of people in the UK could be experiencing early nerve symptoms without realising the cause’.
According to Dr Jack Ogden, a GP in Bristol, symptoms can include burning sensations in the legs, difficulty with coordination and fine motor skills, sensitivity to touch, fatigue and mood or concentration problems.
Professor Boobis added: ‘It takes time for nerve damage to develop, typically a few months.’
Pharmacist Deborah Grayson said: ‘There is certainly a very real risk regarding the levels of vitamin B6 in energy drinks, particularly when combined with other sources.
‘While vitamin B6 is essential, the manufactured forms can cause health problems when consumed in excess.’
This was the harsh reality for one 23-year-old Australian woman who recently revealed her experience in a TikTok video posted under the handle @Kate4102.
She explained how she initially dismissed her troubling symptoms of dizziness, muscle cramps and brain fog, believing they were neurological problems linked to back surgery she had undergone.
But after hearing about a GP with a severe case of B6 toxicity on the news, she began to question whether her own symptoms could be down to the same issue.
And she finally decided to seek medical advice after noticing a bald patch on her head.
A blood test confirmed that she had dangerously high levels of vitamin B6 in her system – so severe she ‘nearly had to have kidney dialysis’. She said energy drinks were her ‘main culprit at one point’.
Her levels have since declined, but the episode has had a lasting impact on her day-to-day life. ‘I couldn’t drive for a while. I couldn’t work properly.
‘I couldn’t even walk properly because I felt so dizzy – like I was on a boat,’ she said.
Red Bull and Monster were approached for comment.
