Formication is the sensation resembling that of small
insect
Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs ...
s crawling on (or under) the skin when nothing is actually there. 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
Particulates – also known as atmospheric aerosol particles, atmospheric particulate matter, particulate matter (PM) or suspended particulate matter (SPM) – are microscopic particles of solid or liquid matter suspended in the air. The ...
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
entomologist
Entomology () is the scientific study of insects, a branch of zoology. In the past the term "insect" was less specific, and historically the definition of entomology would also include the study of animals in other arthropod groups, such as arach ...
s.
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 (]methamphetamine
Methamphetamine (contracted from ) is a potent central nervous system (CNS) stimulant that is mainly used as a recreational drug and less commonly as a second-line treatment for attention deficit hyperactivity disorder and obesity. Meth ...
, Datura, cocaine, MDMA
3,4-Methylenedioxymethamphetamine (MDMA), commonly seen in tablet form (ecstasy) and crystal form (molly or mandy), is a potent empathogen–entactogen with stimulant properties primarily used for recreational purposes. The desired ...
aka ecstasy) or alcohol withdrawal in alcoholics (i.e. delirium tremens), and is often accompanied by visual hallucinations of insects (formicanopia).[ It can also occur as a symptom of ]benzodiazepine withdrawal
Benzodiazepine withdrawal syndrome often abbreviated to benzo withdrawal or BZD withdrawal is the cluster of signs and symptoms that may emerge when a person who has been taking benzodiazepines, either medically or recreationally develops a phy ...
, withdrawal from medication such as SSRI
Selective serotonin reuptake inhibitors (SSRIs) are a class of drugs that are typically used as antidepressants in the treatment of major depressive disorder, anxiety disorders, and other psychological conditions.
SSRIs increase the extrace ...
/ SNRI antidepressants and tramadol; and as a side effect of opioid
Opioids are substances that act on opioid receptors to produce morphine-like effects. Medically they are primarily used for pain relief, including anesthesia. Other medical uses include suppression of diarrhea, replacement therapy for opioi ...
analgesics.
History
Formication is etymologically derived from the Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power ...
word ''formica'', meaning " ant", precisely because of this similarity in sensation to that of crawling insects. The term has been in use for several hundred years. In the 1797 edition of the Encyclopædia Britannica
The ( Latin for "British Encyclopædia") is a general knowledge English-language encyclopaedia. It is published by Encyclopædia Britannica, Inc.; the company has existed since the 18th century, although it has changed ownership various ...
, a description of the condition raphania includes the symptom:
Described again in an instructional text from 1890:
A variety of itching, often encountered in the eczema of elderly people, is formication; this is described as exactly like the crawling of myriads of animals over the skin. It is probably due to the successive irritation of nerve fibrils in the skin. At times patients who suffer from it will scarcely be persuaded that it is not due to insects. Yielding to the temptation to scratch invariably makes the disease worse.[Jamieson, William Allan (1894]
''Diseases of the Skin: A Manual for Practitioners and Students''
Pentland
See also
* Antipruritics – anti-itch drugs
* Morgellons
References
External links
{{Delusion
Hallucinations
Symptoms and signs of mental disorders
Substance dependence
Delusional parasitosis