Evidence browser

Multiple chemical sensitivity and chronic fatigue syndrome in British Gulf War veterans.

Reid, S, Hotopf, M, Hull, L et al.·American journal of epidemiology·2001

This study looked at how often ME/CFS and multiple chemical sensitivity (MCS—a condition where people react badly to everyday chemicals) occurred in British military personnel who served in the Gulf War. Researchers compared three groups: those deployed to the Gulf, those sent to Bosnia, and those who served during the Gulf War period but weren't deployed. They found that both conditions were more common in Gulf veterans, and MCS was strongly linked to pesticide exposure.

Pain and SensitizationSleepCognitive Impairment

Overlapping conditions among patients with chronic fatigue syndrome, fibromyalgia, and temporomandibular disorder.

Aaron, L A, Burke, M M, Buchwald, D·Archives of internal medicine·2000

This study found that ME/CFS, fibromyalgia, and temporomandibular disorder (TMD) often occur together in the same patients and share similar symptoms like pain, fatigue, and sleep problems. The researchers also discovered that patients with these conditions frequently experience other illnesses like irritable bowel syndrome and headaches—much more often than healthy people do. The study suggests these conditions may be connected in some way we don't yet fully understand.

Odor perception: multiple chemical sensitivities, chronic fatigue, and asthma.

Caccappolo, E, Kipen, H, Kelly-McNeil, K et al.·Journal of occupational and environmental medicine·2000

This study tested whether people with chemical sensitivities, chronic fatigue, and asthma have unusually sensitive noses. Researchers measured how well different groups could smell odors and identify them. While people with chemical sensitivities didn't actually detect odors at lower levels than others, they did report feeling more physical symptoms and found certain smells more unpleasant than other groups did.

Self-reported sensitivity to chemical exposures in five clinical populations and healthy controls.

Nawab, S S, Miller, C S, Dale, J K et al.·Psychiatry research·2000

This study asked 225 people—including those with ME/CFS, SAD, and other conditions, plus healthy volunteers—to report how sensitive they are to everyday chemical exposures like perfumes, cleaning products, and other odors. People with ME/CFS reported significantly higher chemical sensitivity than healthy controls, and women reported more sensitivity than men. The researchers suggest that chemical sensitivity may be connected to how the body's stress-response system (the HPA axis) functions.

Prevalence of chronic fatigue and chemical sensitivities in Gulf Registry Veterans.

Kipen, H M, Hallman, W, Kang, H et al.·Archives of environmental health·1999

This study looked at symptoms reported by Gulf War veterans to see how many experienced chronic fatigue and chemical sensitivities. Researchers found that about 16% of veterans met the standard criteria for ME/CFS, about 13% had multiple chemical sensitivities, and a small percentage had both conditions. The findings suggest these conditions were common among Gulf War veterans, though the study was based only on questionnaire responses rather than medical exams.

E2 ModerateBehavioralPEM unclearCross-Sectional

The role of depression in pain, psychophysiological syndromes and medically unexplained symptoms associated with chronic fatigue syndrome.

Morriss, R K, Ahmed, M, Wearden, A J et al.·Journal of affective disorders·1999

This study looked at whether depression makes ME/CFS symptoms worse. Researchers compared three groups: ME/CFS patients without depression, ME/CFS patients with depression, and people with depression alone. They found that depression did not increase pain, headaches, or other unexplained symptoms in ME/CFS patients, but it did make their social life more difficult.

The relationship between fibromyalgia and interstitial cystitis.

Clauw, D J, Schmidt, M, Radulovic, D et al.·Journal of psychiatric research·1997

This study compared symptom patterns in people with fibromyalgia, interstitial cystitis (a bladder pain condition), and healthy people. Researchers found that fibromyalgia and IC patients reported very similar types of symptoms beyond their primary complaints, and both groups showed increased pain sensitivity throughout their bodies—not just in the areas they typically experienced pain.

E2 ModerateCohortPEM unclearObservational

Effect of noise stress on chronic fatigue syndrome patients.

Beh, H C·The Journal of nervous and mental disease·1997

This study looked at how noise affects people with ME/CFS, examining whether environmental sounds make their symptoms worse. The research observed how patients responded to noise stress as part of understanding the condition better. This type of research helps identify triggers that may worsen fatigue and other ME/CFS symptoms.

The localization of pain in chronic fatigue syndrome on a pain drawing according to grid areas.

Líndal, E, Bergmann, S, Thorlacius, S et al.·Perceptual and motor skills·1996

This study looked at where people with ME/CFS experience pain by having them mark painful areas on a body diagram divided into sections. The researchers wanted to understand the pattern of pain locations across different body regions in ME/CFS patients. This type of mapping can help doctors better understand how pain is distributed in the condition.

Pain and SensitizationSleep

Primary juvenile fibromyalgia syndrome and chronic fatigue syndrome in adolescents.

Bell, D S, Bell, K M, Cheney, P R·Clinical infectious diseases : an official publication of the Infectious Diseases Society of America·1994

This study looked at whether children diagnosed with chronic fatigue syndrome (CFS) also had fibromyalgia, a condition involving widespread muscle pain and tender points. Researchers found that about 30% of children with CFS met the criteria for fibromyalgia, and these children experienced more muscle pain, sleep problems, and neurological symptoms than those without fibromyalgia. The study suggests that CFS and fibromyalgia in children may be closely related or even the same condition.

Pain and SensitizationSleep

Sleep, Epstein-Barr virus infection, musculoskeletal pain, and depressive symptoms in chronic fatigue syndrome.

Whelton, C L, Salit, I, Moldofsky, H·The Journal of rheumatology·1992

This study compared sleep patterns, virus exposure, and symptoms in 14 ME/CFS patients versus 12 healthy people. Patients reported sleep that didn't feel refreshing and had unusual brain wave patterns during sleep, but didn't show excessive daytime sleepiness. The study found no evidence that a chronic Epstein-Barr virus infection was causing the illness, but patients did have more widespread pain, tender points, and depression symptoms.

High frequency of fibromyalgia in patients with chronic fatigue seen in a primary care practice.

Goldenberg, D L, Simms, R W, Geiger, A et al.·Arthritis and rheumatism·1990

This study looked at whether people with chronic fatigue also have fibromyalgia, a condition involving widespread muscle pain and tender points. Researchers examined 27 patients with debilitating fatigue lasting at least 6 months and found that 70% of them had the widespread pain and tender points typical of fibromyalgia. This suggests that many people with chronic fatigue may also have fibromyalgia.

E3 PreliminaryCohortPEM requiredCase-Control

Significant aggravation of pre-existing myalgic encephalomyelitis/chronic fatigue syndrome following proton beam therapy for sphenoid wing meningioma: case report.

Fischer, Christian, Seidlitz, Annekatrin, Krause, Mechthild·Strahlentherapie und Onkologie : Organ der Deutschen Rontgengesellschaft ... [et al]·2026

This is a single case report of a 46-year-old woman with ME/CFS whose condition severely worsened after receiving proton beam radiation therapy for a brain tumor. Over months following treatment, she went from being ambulatory to completely bedridden, with worsening fatigue, pain, dizziness, and cognitive problems. The report suggests that radiation may have triggered this deterioration, but it remains unclear whether this outcome would occur in other ME/CFS patients undergoing similar treatment.

Pain and SensitizationSevere MEEnergy MetabolismCognitive Impairment

E3 PreliminaryReviewPEM not requiredReview-Narrative

Myopraktikk (NO): A Narrative Review and Conceptual Hypothesis on Intrafasciomembranal Fluid Pressure, Biotensegrity, and Immediate Remote Myofascial Responses.

Hopen, Stig Runar, Mjøen, Tor Arne·Cureus·2025

This article proposes a new theory about muscle pain and stiffness called Myopraktikk, which focuses on fluid pressure building up in the spaces around muscles. The authors suggest that when fluid pressure increases in these areas, it can cause muscles to feel tight, knotted, and painful—similar to what happens in conditions like ME/CFS and fibromyalgia. According to their hypothesis, releasing this pressure through manual treatment may help reduce symptoms in both the treated area and elsewhere in the body.

E3 PreliminaryBehavioralPEM unclearLongitudinal

Disentangling pain and fatigue in chronic fatigue syndrome: a resting state connectivity study before and after cognitive behavioral therapy.

van der Schaaf, Marieke E, Geerligs, Linda, Toni, Ivan et al.·Psychological medicine·2024

This study looked at how fatigue and pain affect different networks in the brain of ME/CFS patients by taking brain scans at rest. The researchers found that fatigue and pain involve different brain circuits, suggesting they may be caused by different mechanisms. After cognitive behavioral therapy (CBT), patients who improved showed better communication between brain regions associated with movement and the brain's resting network.

E3 PreliminaryReviewPEM unclearReview-Narrative

Current understanding of nociplastic pain.

Yoo, Yeong-Min, Kim, Kyung-Hoon·The Korean journal of pain·2024

This article explains 'nociplastic pain'—a type of chronic pain that occurs when the nervous system becomes overly sensitive to pain signals, even when there is no obvious tissue damage or nerve injury. People with ME/CFS, fibromyalgia, and similar conditions often experience this kind of pain. The article describes how doctors can recognize nociplastic pain and groups it with other conditions that share this same underlying mechanism of nervous system sensitivity.

E3 PreliminaryCohortPEM not requiredCase-Control

Oxygen-ozone autohemotherapy in breast cancer patients suffering from fatigue and musculoskeletal pain upon aromatase inhibitors treatment: a case-series study.

Tirelli, U, Valdenassi, L, Franzini, M et al.·European review for medical and pharmacological sciences·2023

This study looked at six breast cancer patients taking a hormone therapy drug (anastrozole) who experienced severe pain, weakness, and fatigue as side effects. These patients received oxygen-ozone therapy, a treatment where blood is mixed with ozone gas and returned to the body. After treatment, patients reported significant reductions in both pain and fatigue that lasted for several months.

E3 PreliminaryReviewPEM not requiredReview-Narrative

Exploring the scope of homoeopathy in combating the unfortunate consequences of post-COVID-19 survivors based on non-COVID conditions: a narrative review.

Dixit, Ashish Kumar, Giri, Nibha, Singh, Shishir·Journal of complementary & integrative medicine·2023

This review looked at whether homeopathy—a complementary medicine approach—might help people recover from long-term symptoms after COVID-19. The authors searched published research and found that homeopathy has shown some promise in treating anxiety, depression, pain, and heart problems in other conditions, and they suggest it might be worth studying for post-COVID recovery.