Introduction: Keratin-based hair straightening product are widely used worldwide to straighten hair. Historically, many keratin-based hair straightening products contained formaldehyde. However, several studies have shown its genotoxic and carcinogenic potential. As a result, it was replaced with glyoxyloyl carbocystein, and later with glyoxylic acid, under the assumption that these alternatives were less harmful.

Observation: We reported a case of 25-year-old female who developed an Acute Kidney Injury (AKI) after the application of a formaldehyde-free keratin-based hair straightening product which contained glyoxylic acid. The patient exhibited classic biochemical features of AKI, including elevated serum creatinine (3.2 mg/dL), Blood Urea Nitrogen (45 mg/dL), and hyperkalemia (6.2 mmol/L). There were also signs of metabolic acidosis, including low pH (7.25), and low bicarbonates (18 mmol/L). Liver enzymes are within normal limits, indicating no significant hepatic dysfunction. Her kidney function improved after appropriate management. Four similar cases have been reported in the literature, emphasizing the nephrotoxicity linked to the use of glyoxylic acid in hair straightening formulations.

Conclusion: Clinicians should be aware of the potential renal risks associated with keratin-based hair straightening product, especially in patients presenting with unexplained renal dysfunction following recent hair treatments.