Methemoglobinemia from perineal application of an anesthetic cream.

A 34-year-old woman presented with cyanosis and a methemoglobin level of 23.2% after perineal application of a topical anesthetic cream containing 20% benzocaine. Many commonly used products contain high levels of benzocaine, and their use can lead to life-threatening methemoglobin levels. This case reinforces the need for stricter guidelines for product use and warning labels to alert consumers to this potential side effect of topical benzocaine-containing products sold over the counter.