Hyperesthesia (or hyperaesthesia) is a condition that involves an abnormal increase in sensitivity to stimuli of the sense. "When a non-noxious stimulus causes the sensation of pain the area will be termed hyperaesthetic". Stimuli of the senses can include sound that one hears, foods that one tastes, textures that one feels, and so forth. Increased touch sensitivity is referred to as "tactile hyperesthesia", and increased sound sensitivity is called "auditory hyperesthesia". Tactile hyperesthesia may be a common symptom of many neurologic disorders such as herpes zoster, peripheral neuropathy and radiculopathies. In 1979, and then in 1994, Merskey, Bogduk, Noordenbos, Devor and others (a subcommittee of International Association for the Study of Pain) proposed, instead of hyperaesthesia, the concept of allodynia, meaning "other pain", defined as a pain resulting from a stimulus that does not normally provoke pain.

In psychology, Jeanne Siaud-Facchin uses the term by defining it as an "exacerbation des sens" that characterizes gifted children (and adults): for them, the sensory information reaches the brain much faster than the average, and the information is processed in a significantly shorter time.

Feline hyperesthesia syndrome is an uncommon but recognized condition in cats, particularly Siamese, Burmese, Himalayan, and Abyssinian cats. It can affect cats of all ages, though it is most prevalent in mature animals. The disease can be somewhat difficult to detect as it is characterized by brief bursts of abnormal behavior, lasting around a minute or two. One of its symptoms is also found in dogs that have canine distemper disease (CD) caused by canine distemper virus (CDV).

The disease is classically a five-day fever of the relapsing type, rarely exhibiting a continuous course. The incubation period is relatively long, at about two weeks. The onset of symptoms is usually sudden, with high fever, severe headache, pain on moving the eyeballs, soreness of the muscles of the legs and back, and frequently hyperaesthesia of the shins. The initial fever is usually followed in a few days by a single, short rise but there may be many relapses between periods without fever. The most constant symptom is pain in the legs. Recovery takes a month or more. Lethal cases are rare, but in a few cases "the persistent fever might lead to heart failure". Aftereffects may include neurasthenia, cardiac disturbances and myalgia.

"Bartonella quintana" is transmitted by contamination of a skin abrasion or louse-bite wound with the faeces of an infected body louse ("Pediculus humanus corporis"). There have also been reports of an infected louse bite passing on the infection.