Formication

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. 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.

Causes

Causes of formication include normal states such as onset of menopause (i.e. hormone withdrawal). Other causes are medical conditions such as pesticide exposure, mercury poisoning, diabetic neuropathy, skin cancer, syphilis, Lyme disease, hypocalcaemia, or herpes zoster (shingles) and neurocysticercosis. Formication can be a result of stimulant intoxication or withdrawal from methamphetamine, Datura, cocaine, or alcohol in alcoholics (i.e. delirium tremens), and is often accompanied by visual hallucinations of insects. It can also occur as a symptom of benzodiazepine withdrawal, withdrawal from medication such as SSRI/SNRI antidepressants and tramadol; and as a side effect of opioid analgesics.