Recent use of formaldehyde-'free' hair straightening product and severe acute kidney injury.

Formaldehyde is present in hair straightening products even when labeled as formaldehyde-free. Inhaled absorption of formaldehyde causes renal tubular cytotoxicity. We report a teenager who developed severe acute kidney injury requiring renal replacement therapy shortly after exposure to a formaldehyde-'free' hair straightening product. Kidney biopsy showed acute tubular necrosis and images compatible with microcalcifications. Kidney function improved while on continuous venous-venous hemodialysis.