The Food and Drug Administration is warning that dozens of hand sanitizers should be avoided after they tested positive for the toxic substance methanol.

The agency issued the alert July 2 while warning about the effects of methanol, which can cause servere side effects when absorbed through the skin. In total, the FDA has added 46 hand sanitizer brands to its list of toxic products.

"The agency is aware of adults and children ingesting hand sanitizer products contaminated with methanol that has led to recent adverse events including blindness, hospitalizations and death," the agency said in a statement.

Consumers who have been exposed to the substance while using hand sanitizer should seek treatment to reverse its effects, the FDA said. Exposure can result in vomiting, headaches, blurred vision, blindness, seizures, nausea, permanent damage to the nervous system and even death.

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The agency said it has seen a spike in hand sanitizer products claiming to contain ethanol, but have tested positive for methanol. The FDA announced last month that nine hand sanitizer products should be avoided because of the possible presence of the substance.

The FDAs list contains 59 toxic products, some of which have been recalled. All appeared to have been made in Mexico.