Formication is a type of tactile hallucination; the sensation that insects are crawling on (or in) a person’s skin, a feeling similar to pins and needles.
The term stems from the Latin for ant: ‘formica’. It can be experienced in diabetes or Parkinson’s patients, or in cases of substance abuse, which was first reported in 1889. When one person in a household experiences formication, it can spread like an infestation to other family members who may feel like they have been ‘infected’ – this phenomenon is known folie à deux, or ‘madness of two’.
Unfortunately as a consequence of this sensation, patients often scratch their skin obsessively, which can cause bleeding and infections. Currently, it can only be treated in some cases by antihistamines, or infrared laser therapy in more severe cases.