Meth mites. Amphetamites. Coke bugs. Drug users find many nicknames for hallucinations of bugs crawling on skin. But the scientific term is “delusional parasitosis”, a condition characterized by an individual’s mistaken, deep-seated belief that he or she has a serious parasite or insect infestation.
In some cases, the condition results from the use or abuse of one of several different illegal drugs and legal medications. In the United States, this form of parasitosis belongs to a larger group of conditions known collectively as “psychotic disorder due to a general medical condition.” One of the main symptoms of substance-induced delusional parasitosis is formication, a touch-based (tactile) hallucination that produces a feeling similar to bugs crawling on a person’s skin.
Delusional parasitosis basics
Delusional parasitosis has no official status as a distinct mental disorder in the U.S. Instead, its standard definition comes from the World Health Organization, which lists the disorder in a comprehensive reference guide called the International Classification of Diseases (ICD). However, the standard American mental health guide, known as the Diagnostic and Statistical Manual of Mental Disorders (DSM), contains categories of illness that roughly parallel the symptoms of delusional parasitosis.
Delusional parasitosis itself comes in three main forms, known respectively as primary, secondary functional, and secondary organic delusional parasitosis. People with the primary form of the disorder have insect- or parasite-related delusions, but no other sign of mental illness or significantly abnormal thought processes; the rough DSM equivalent of this form of delusional parasitosis is called “delusional disorder, somatic type.” People with the secondary functional form of delusional parasitosis have insect- or parasite-related delusions that stem from the presence of depressive illness, schizophrenia, or some other mental disorder. People with secondary organic delusional parasitosis have delusions related to drug abuse, medication side effects or a variety of medical conditions that include diabetes, low thyroid function, nervous system abnormalities and certain types of cancer. It is this form of the disorder that roughly corresponds with the DSM’s “psychotic disorder due to a medical condition.”
The term “formication” comes from the Latin word “formicare,” which describes the multi-legged walking patterns of ants. As indicated previously, people with this delusional parasitosis symptom feel as if they have bugs crawling over their skin or, in some cases, within the skin itself. Depending on the perspective taken by the medical professional diagnosing the affected individual, formication qualifies as either a form of tactile hallucination or as a form of abnormal nerve-related sensation known as a paresthesia (other paresthesias include abnormal tingling, burning, or numbness in a given part of the body).
Drugs causing hallucinations of bugs
Doctors first described the effects of formication in the 1880s while examining people with long-term histories of extensive cocaine use. Other illegal drugs associated with the onset of the symptom include methamphetamine, MDMA (Ecstasy) and certain types of narcotics (opioids). Legal substances associated with formication include alcohol, a hypnotic (sleep-producing) medication called eszopiclone (Lunesta), the amphetamine-based ADHD medication dextro/levo-amphetamine (Adderall), the amphetamine-like ADHD medication methylphenidate (Ritalin), the antidepressant/smoking cessation medication buproprion (Wellbutrin, Zyban), and the antiepileptic medication levetiracetam (Keppra). In some cases, formication occurs during active use of a given substance; in other cases, it occurs during withdrawal from a substance.
People with substance-induced formication frequently scratch and pick their skin extensively, especially while under the active influence of the substance responsible for their symptoms. In many cases, this scratching and picking leads to the formation of sores, ulcers, or other significant lesions on the affected skin. In relatively rare cases, people suffering from formication may take more extreme measures and cut open their skin in an attempt to locate and remove the “bugs” responsible for crawling sensations that seem to come from within the skin layers. According to a study published in 2009 in Infections in Medicine, common body locations for formication-related sensations include the face, forearms, upper thighs, neck, and scalp. In addition to formication, people with substance-induced delusional parasitosis sometimes “see” insects or parasites on their skin or crawling out of their skin.
Trouble accepting the diagnosis
Drug users affected by formication often refuse to believe that their symptoms don’t stem from the actual presence of parasites or insects on or in their skin. As a result, they frequently seek a diagnosis from multiple physicians or withdraw from medical care out of suspicion over the motives of the doctors who diagnose them.