Hyperalgesia

Hyperalgesia is an abnormal increase in sensitivity or an amplification of normally painful or uncomfortable stimulus. A person with hyperalgesia experiences an excessive amount of pain compared to the physical severity of damage or illness in their body.

Generalized hyperalgesia is common in fibromyalgia (FMS) and chronic fatigue syndrome (ME/CFS) and some studies indicate it may be partly caused by a mechanism in which microglial accumulation and activation is involved, as well as other possible immune system changes, such as complement system product C4a.

Symptom recognition
Hypersensitivity to pain is a sensory symptom recognized in the Canadian Consensus Criteria for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome, and hyperalgesia is one of the examples of significant pain included in the International Consensus Criteria for Myalgic Encephalomyelitis. 

Notable studies

 * 2010, Evidence for generalized hyperalgesia in chronic fatigue syndrome: a case control study
 * 2014, A chronic fatigue syndrome model demonstrates mechanical allodynia and muscular hyperalgesia via spinal microglial activation
 * 2019, Exercise-induce hyperalgesia, complement system and elastase activation in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome - a secondary analysis of experimental comparative studies

Learn more

 * Hyperalgesia: Causes, Symptoms, Treatment, and More - WebMD
 * Allodynia and Hyperalgesia in Neuropathic Pain Fact Sheet - International Association for the Study of Pain