Formication

Formication
Specialty	Psychiatry, neurology

Formication is the sensation resembling that of small insects crawling on (or under) the skin, in the absence of actual insects. It is one specific form of a set of sensations known as paresthesias, which also include the more common prickling, tingling sensation known as pins and needles. Formication is a well-documented symptom which has numerous possible causes. The word is derived from formica, the Latin word for ant.

Formication may sometimes be experienced as feelings of itchiness, tingling, pins and needles, burning, or even pain. When formication is perceived as itchiness, it may trigger the scratch reflex, and, because of this, some people who experience the sensation are at risk of causing skin damage through excessive scratching.

In some cases, static electricity can attract particulates to the skin and can also cause body hair to move, giving a sensation like insects crawling over the skin.^[1] However, in many cases no external trigger creates the sensation.

In rare cases, individuals become convinced the sensation is due to the presence of real insects on or under the skin. Such patients have what is known as delusional parasitosis. They believe their skin is inhabited by, or under attack by, small insects or similar parasites, despite repeated reassurances from physicians, pest control experts, and entomologists.^[2]