Doctors in the United Kingdom have put out new warnings about the hidden dangers of green tea, after a teenage girl who drank three cups a day for months contracted acute hepatitis from the herbal remedy, The Telegraph reports.

According to BMJ Case Reports, which published the original story, a 16-year-old U.K. girl ordered the tea online from China in a bid to lose weight. Three months into the regimen, she went to her doctor complaining of dizziness, stomach and joint pains.

She was initially told she had a urinary tract infection and was sent home with antibiotics. However, two days later, the teen started suffering from jaundice, causing the skin and the whites of her eyes to turn yellow. She headed to Birmingham University Hospital seeking urgent treatment.

The medical team there immediately diagnosed her with hepatitis, a swelling or inflammation of the liver that can either be caused by a virus or when the liver is exposed to harmful toxins. The girl said she had not recently consumed any alcohol, drugs or prescription medications before getting ill.

Fortunately, after the girl stopped drinking the green tea, she rapidly recovered from the condition. Doctors wrote that it was possible that the addition of unknown chemicals to the tea, perhaps to help aid in weight loss, or pesticides used on the product, may have also contributed to her illness.

The report warns that many herbal supplements—especially when sourced from developing countries or bought online—are not closely regulated by health authorities, and that consumers should be careful when ordering these products.