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 negative.

Meanwhile, the swelling around one of his eyes spread to both eyes and then across his face, while his blood pressure continued to fall despite treatment with intravenous fluids.

The doctors probed further into the man's medical history and activities before the fainting episodes. They learned that he had applied an artificial hair dye two days before he became ill. Soon afterward, he developed itching on his scalp, neck and face. He self-treated with the allergy medicine cetirizine, an antihistamine, for two days. He also reported spending two to three hours outdoors in the sun each day after he'd applied the hair dye.

The diagnosis: Based on the man's recent use of hair dye, the itching that followed, his rapidly worsening facial swelling and his persistently low blood pressure, doctors concluded that he was experiencing anaphylaxis, a severe allergic reaction that can affect the whole body. The reaction can be life-threatening if left untreated.

The treatment: Doctors treated the man with epinephrine (also called adrenaline), a hormonal medication that rapidly reverses the effects of anaphylaxis. They also gave him antihistamines and steroids to help bring the allergic reaction under control, along with intravenous fluids to raise his blood pressure.

However, the patient's blood pressure remained dangerously low, so doctors continued giving him epinephrine through an intravenous drip for about 16 hours. Over the next three days of treatment, his blood pressure stabilized and the swelling in his face gradually subsided.

He was transferred to a general ward and treated there for another five days before being discharged. He was advised that he could have a similar reaction in the future and referred to a dermatologist.

What makes the case unique: Most allergic reactions to hair dye remain limited to the skin, causing itching, redness and swelling where the dye has touched it. Severe reactions affecting the whole body are uncommon, the man's doctors wrote in a report of the case.

The itching the man noticed shortly after applying the dye was likely an early, mild allergic reaction, his doctors wrote. That reaction later progressed to a much more severe one, they suggested, raising the possibility of a "biphasic" allergic reaction, an uncommon pattern seen in about 5% of patients with anaphylaxis. However, this remains only a possible explanation.

The doctors also noted that the man's prolonged sun exposure after he applied the dye may have intensified the reaction; they cited previous research that ultraviolet light can enhance the allergy-triggering effects of para-phenylenediamine, a common ingredient in hair dyes. In the report, the doctors did not identify the exact hair dye ingredient that triggered the reaction in this instance.

The case highlights the importance of asking about recent use of products such as hair dye when doctors evaluate patients with otherwise unexplained fainting, facial swelling or shock, the medical team concluded.

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