 Low concentrations of an antiseptic may encourage growth of a bacterial strain that is resistant to the antiseptic, where a higher concentration of the antiseptic would simply kill the bacteria.In addition, use of an excessively high concentration of an antiseptic may cause tissue damage or slow the process of wound healing.Consequently, antiseptics are most effective when used at the correct concentration—a high enough concentration to kill harmful bacteria, fungi or viruses, but a low enough concentration to avoid damage to the tissue.