Chemical avulsion of the overgrowing nail plate with urea ointment is useful and
provides considerable relief of the patient’s discomfort. Different formulations can be
used, ranging from a simple 40% urea in 60% white petrolatum preparation, to the South
and Farber’s ointment, which has the following formulation: urea 40%, white beeswax
5%, anhydrous lanolin 20%, white petrolatum 25%, micronized silica gel 10%. Before
the ointment is applied to the nail plate surface, it is mandatory to cover the periungual
skin with plastic tape in order to protect the skin from maceration. The urea ointment is
then applied to the nail and covered with a plastic wrap; the medication is fixed to the
digit with a plastic tape and maintained in place for 7–10 days. Finally, the medication is
wiped off and the softened nail plate is removed using nail clippers.
Chemical nail avulsion is only effective when the nail plate is partially or totally
detached from the nail bed. It is not useful on normal nails, but can be successful in
removing onychomycotic nails as well as thickened psoriatic nails.