Benzocaine has been used since the early 1900’s for medical applications such as surface pain and itch reduction among other uses. Benzocaine has a very low toxicity as the LD50 for it is approx. 3,000 mg/kg of body weight (Rat). Benzocaine is not soluble in water. It is soluble in alcohol or hydrocarbons. The hydrochloride or “HCl” form is freely soluble in water. This is an important fact to be considered when developing a topical cream or ointment using these as an ingredient. Benzocaine is also used in some oral numbing products. The maximum concentration allowed by the FDA in a Benzocaine Topical product is 20%.
Benzocaine works by blocking Sodium Channels in the neuronal cell membrane. Although rare, Methemoglobinemia can result from high blood concentrations in individuals who have certain risk factors. This is the reason why it is important when developing a topical skin product with Benzocaine there must be FDA approval before the product goes to market. If used properly, Benzocaine continues to be a very useful ingredient in topical skin itch and numbing products around the world.