While Over The Counter (OTC) numbing creams are limited to 5% Lidocaine Zensa numbing cream is not the strongest. Tattoo Numbing Cream Co. contains both 5% Lidocaine and 5% Prilocaine. Prilocaine is a second numbing agent. Tattoo Numbing Cream Co. also includes 1% epinephrine a powerful vasoconstrictor.