Over the counter Permethrin products carry the statement that Permethrin is a clothing treatment only, and is not to be worn next to the skin. Permethrin is labeled for clothing treatment only and is not to be applied to, or come in direct contact with the skin. This is because, while there are no known side effects of Permethrin usage, no long-term (40 year) studies have been done to determine if there are any long-term usage effects. Therefore, Permethrin should not be used on headphones or headphone foam coverings, or in any manner not specifically indicated on the product label.