Unexpected Source for Itch

TAKE-HOME LEARNING POINTS

• Pediculosis capitis (head lice) is seen mostly in children but affects adults as well.

• Pyoderma, secondary to scratching, can mislead the diagnostician and thereby delay diagnosis of the underlying problem.

• Oral trimethoprim/sulfa is often used to treat lice-associated pyoderma but does nothing directly to kill the lice themselves.

• The itching from head lice is a delayed hypersensitivity reaction to the lice protein and can take months after infestation to develop.

• Conversely, itching will develop early on in patients who have been sensitized by having had head lice in the past.

• The use of topical ivermectin has proven to be exceptionally effective in clinical trials.

DISCLOSURE: The author discloses having spoken and written about topical ivermectin at the behest of the manufacturer, but this article was not part of that process, nor is it supported by the product’s manufacturer in any way.