Diagnostic dilemma: A man's sudden fainting episodes landed him in the hospital — and a hair dye was to blame

The patient: A 61-year-old man in India

The symptoms: The man went to an emergency department after fainting. He had felt nauseous just before the episode, which lasted about three minutes and was followed by a second fainting episode lasting about two minutes. He also had swelling around one eye.

His family told doctors that he hadn't shown any jerking movements, loss of bladder control or subsequent grogginess, which would have been telltale signs of a seizure.

What happened next: Because the man had fainted twice and had a history of heart disease, doctors first looked for problems affecting his brain and heart. An MRI of his brain, used to look for structural abnormalities that could explain the fainting, and an electroencephalogram (EEG), which records the brain's electrical activity, did not reveal a cause.

The man had persistently low blood pressure, the doctors observed, and this led them to move him to the intensive care unit. There, doctors carried out tests for infections and heart attack, but all came back n...