Often overlooked, the side-effects of topical creams is more important than credited. Lidocaine is a topical numbing agent frequently used before mammograms. The cream is spread on the skin and allowed to absorb for 45 minutes. It is also used to dull pain from laser hair removal, or any other surgery covering a large amount of skin. Research studies found no side-effects; however, the clinical trial did not have enough of a sample size to account for rare and unusual side effects.

This became apparent when two women spread lidocaine and tetracaine on their legs, covered it in plastic, and left it for 45 minutes. They experiences seizures, fell into comas, and died.

Experts theorize that broken skin or elevated temperature might have raised the amount of the drug entering the bloodstream to toxic levels.

When using topical analgesic, use the minimum amount, and avoid broken skin.