Formication is the sensation resembling that of small

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

s crawling on (or under) the skin, in the absence of actual insects. It is one specific form of a set of sensations known as

paresthesia Paresthesia is a sensation of the skin that may feel like numbness (''hypoesthesia''), tingling, pricking, chilling, or burning. It can be temporary or Chronic condition, chronic and has many possible underlying causes. Paresthesia is usually p ...

s, 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 Ants are Eusociality, eusocial insects of the Family (biology), family Formicidae and, along with the related wasps and bees, belong to the Taxonomy (biology), order Hymenoptera. Ants evolved from Vespoidea, vespoid wasp ancestors in the Cre ...

. Formication may sometimes be experienced as feelings of

itchiness An itch (also known as pruritus) is a sensation that causes a strong desire or reflex to scratch. Itches have resisted many attempts to be classified as any one type of sensory experience. Itches have many similarities to pain, and while both ...

, 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 Static electricity is an imbalance of electric charges within or on the surface of a material. The charge remains until it can move away by an electric current or electrical discharge. The word "static" is used to differentiate it from electric ...

can attract

particulates Particulate matter (PM) or particulates are microscopic particles of solid or liquid matter suspension (chemistry), suspended in the atmosphere of Earth, air. An ''aerosol'' is a mixture of particulates and air, as opposed to the particulate ...

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 Delusional parasitosis (DP), also called delusional infestation, is a mental health condition where a person falsely believes that their body is infested with living or nonliving agents. Common examples of such agents include parasites, insects, o ...

. They believe their skin is inhabited by, or under attack by, small insects or similar parasites, despite repeated reassurances from physicians,

pest control Pest control is the regulation or management of a species defined as a pest (organism), pest; such as any animal, plant or fungus that impacts adversely on human activities or environment. The human response depends on the importance of the da ...

experts, and

entomologist Entomology (from Ancient Greek ἔντομον (''éntomon''), meaning "insect", and -logy from λόγος (''lógos''), meaning "study") is the branch of zoology that focuses on insects. Those who study entomology are known as entomologists. In ...

Causes

Causes of formication include normal states such as onset of

menopause Menopause, also known as the climacteric, is the time when Menstruation, menstrual periods permanently stop, marking the end of the Human reproduction, reproductive stage for the female human. It typically occurs between the ages of 45 and 5 ...

(i.e. hormone withdrawal). Other causes are medical conditions such as pesticide exposure,

mercury poisoning Mercury poisoning is a type of metal poisoning due to exposure to mercury. Symptoms depend upon the type, dose, method, and duration of exposure. They may include muscle weakness, poor coordination, numbness in the hands and feet, skin rashe ...

diabetic neuropathy Diabetic neuropathy includes various types of nerve damage associated with diabetes mellitus. The most common form, diabetic peripheral neuropathy, affects 30% of all diabetic patients. Studies suggests that cutaneous nerve branches, such as the s ...

skin cancer Skin cancers are cancers that arise from the Human skin, skin. They are due to the development of abnormal cells (biology), cells that have the ability to invade or metastasis, spread to other parts of the body. It occurs when skin cells grow ...

syphilis Syphilis () is a sexually transmitted infection caused by the bacterium ''Treponema pallidum'' subspecies ''pallidum''. The signs and symptoms depend on the stage it presents: primary, secondary, latent syphilis, latent or tertiary. The prim ...

Lyme disease Lyme disease, also known as Lyme borreliosis, is a tick-borne disease caused by species of ''Borrelia'' bacteria, Disease vector, transmitted by blood-feeding ticks in the genus ''Ixodes''. It is the most common disease spread by ticks in th ...

, hypocalcaemia, or herpes zoster (shingles) and

neurocysticercosis Neurocysticercosis (NCC) is a Parasitic disease, parasitic infection of the central nervous system, nervous system caused by the larvae of the tapeworm ''Taenia solium,'' also known as the "pork tapeworm". The disease is primarily transmitted ...

. Formication can be a result of stimulant intoxication or withdrawal from

methamphetamine Methamphetamine (contracted from ) is a potent central nervous system (CNS) stimulant that is mainly used as a recreational drug use, recreational or Performance-enhancing substance, performance-enhancing drug and less commonly as a secon ...

Datura ''Datura'' is a genus of nine species of highly poisonous, Vespertine (biology), vespertine-flowering plants belonging to the nightshade family (Solanaceae). They are commonly known as thornapples or jimsonweeds, but are also known as devil's t ...

cocaine Cocaine is a tropane alkaloid and central nervous system stimulant, derived primarily from the leaves of two South American coca plants, ''Erythroxylum coca'' and ''Erythroxylum novogranatense, E. novogranatense'', which are cultivated a ...

, or

alcohol Alcohol may refer to: Common uses * Alcohol (chemistry), a class of compounds * Ethanol, one of several alcohols, commonly known as alcohol in everyday life ** Alcohol (drug), intoxicant found in alcoholic beverages ** Alcoholic beverage, an alco ...

alcoholic Alcoholism is the continued drinking of alcohol despite it causing problems. Some definitions require evidence of dependence and withdrawal. Problematic use of alcohol has been mentioned in the earliest historical records. The World Hea ...

s (i.e.

delirium tremens Delirium tremens (DTs; ) is a rapid onset of confusion usually caused by withdrawal from alcohol. When it occurs, it is often three days into the withdrawal symptoms and lasts for two to three days. Physical effects may include shaking, sh ...

), and is often accompanied by visual hallucinations of insects. It can also occur as a symptom of

benzodiazepine withdrawal Benzodiazepine withdrawal syndrome (BZD withdrawal) is the cluster of signs and symptoms that may emerge when a person who has been taking benzodiazepines as prescribed develops a physical dependence on them and then reduces the dose or stop ...

, 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 primarily work by ...

/ SNRI

antidepressants Antidepressants are a class of medications used to treat major depressive disorder, anxiety disorders, chronic pain, and addiction. Common side effects of antidepressants include dry mouth, weight gain, dizziness, headaches, akathisia, sexu ...

and

tramadol Tramadol, sold under the brand name Tramal among others, is an opioid analgesic, pain medication and a serotonin–norepinephrine reuptake inhibitor (SNRI) used to treat moderately severe pain. When taken by mouth in an immediate-release form ...

; and as a side effect of

opioid Opioids are a class of Drug, drugs that derive from, or mimic, natural substances found in the Papaver somniferum, opium poppy plant. Opioids work on opioid receptors in the brain and other organs to produce a variety of morphine-like effects, ...

analgesics.

History

Formication is etymologically derived from the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

word ''formica'', meaning "

", 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 is a general knowledge, general-knowledge English-language encyclopaedia. It has been published by Encyclopædia Britannica, Inc. since 1768, although the company has changed ownership seven times. The 2010 version of the 15th edition, ...

, 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

References

External links

{{Delusion Hallucinations Symptoms and signs of mental disorders Substance dependence Delusional parasitosis

Causes

History

See also

References

External links