Skin lightening cream causes CNS damage in patient, reports CDC

A skin-lightening cream from Mexico has been found to have had a devastating effect on the central nervous system due to its highly toxic mercury levels as confirmed by a UC San Francisco-led report on a patient. The patient a California woman had significant central nervous system damage and remains unable to care for herself months after ceasing use of the product.

The woman first sought medical help for involuntary muscle movement and weakness in her shoulders and arms, the case study reported. After two weeks of outpatient care, she was admitted to a hospital with symptoms that included blurry vision, unsteady gait and difficulty speaking. Blood and urine tests confirmed mercury poisoning.

The cream was found to contain methylmercury, a form of organic mercury, and is the first case of such poisoning in the United States in nearly 50 years, the authors state in their report, which publishes Dec. 19, 2019, in the Morbidity and Mortality Weekly Report, by the U.S. Centers for Disease Control and Prevention (CDC). This is the first known case of methylmercury poisoning in the United States in nearly 50 years.

“Most harmful skin-lightening creams are intentionally tainted with inorganic mercury,” said senior author Paul Blanc, MD, MSPH, of the UCSF Division of Occupational and Environmental Medicine, and the California Poison Control System, San Francisco Division. “But in this case, the patient used a skin-lightening product containing organic mercury, which is far more toxic. This form of mercury can cause profound damage to the central nervous system that may even worsen after cessation of use.”

The authors recount that the patient initially sought medical help for involuntary muscle movements and weakness of her upper extremities. After two weeks of outpatient care, the patient’s condition had deteriorated. She was admitted to a local hospital with symptoms that had progressed to blurry vision, unsteady gait and difficulty with speech.

"Central nervous system toxicity, as in this case, is the hallmark of organic mercury—it typically comes on after weeks to months of exposure. Once manifested, it quickly progresses and often worsens, despite removal of any further exposure," Blanc said in a UCSF news release. "Unfortunately, chelation therapy, which is effective in inorganic mercury poisoning, has not been established to be efficacious for methylmercury."

Consumers can take several steps to protect themselves, said study co-author Dr. Craig Smollin, of UCSF's emergency department and medical director of the California Poison Control System's San Francisco Division.

When buying skin creams, check that the product has a protective foil seal under the lid, Smollin advised.

"Purchase creams from well-known stores and avoid those with hand-made labels or without labels. Ingredients must be listed, and directions and warnings should be in English," he said in the news release.