The fit and healthy 47-year-old was taken to hospital when she became confused and began grinding her teeth. She then collapsed and had a seizure.
Writing in the journal BMJ Case Reports, doctors from Milton Keynes Hospital NHS Foundation Trust warned of the potential harms of detoxes and told patients to be aware that “all-natural products are not without side effects”.
The woman, who has not been named, was found to have very low levels of salt in her blood, which medics say could be caused by consuming large amounts of the herbal remedy valerian root, which is also a known diuretic.
However more evidence is needed to draw definite conclusions, they warned.
Relatives said she had been taking a string of herbal remedies for various ailments, including milk thistle, vervain, green tea and valerian root.
Her family told medics she had been drinking more tea and water due to increasing thirst but they did not think it was excessive.
The doctors, led by Dr Oliver Toovey, said: “The complementary medicine market is very popular in the UK and the concept of the New Year ‘detox’ with all-natural products is appealing to those less concerned with evidence-based medicine and more with complementary medicine.
“Excessive water intake as a way of ‘purifying and cleansing’ the body is also a popular regime with the belief that harmful waste products can thus be washed from the body.
“Despite marketing suggesting otherwise, all-natural products are not without side effects.”
Many people mistakenly believe that drinking excessive amounts of water will cleanse their system, said Edinburgh nutritionist Emma Conroy.
She added: “There is a wealth of natural medicine that is scientifically verified but you should always go for tried and tested brands.
“If a detox seems to good to be true then it probably is.”