DC 6354Infectious DiseasesLast verified: APR 22, 2026

Secondary Conditions for Chronic Fatigue Syndrome (CFS/ME)

Chronic Fatigue Syndrome (CFS/ME) is a service-connected condition that can cause or aggravate 1 additional disability under 38 CFR § 3.310. Common secondaries include Fibromyalgia (Gulf War-Associated). Each secondary requires medical nexus evidence linking it to the primary, documented in treatment records or a private nexus letter.

“Disability which is proximately due to or the result of a service-connected disease or injury shall be service connected.”
— 38 CFR § 3.310(a), Disabilities that are proximately due to, or aggravated by, service-connected disease or injury
Evidence Strength:STRONGMODERATEEMERGING

Which secondary conditions are most common after Chronic Fatigue Syndrome (CFS/ME)?

MODERATE

Medical Rationale

Fibromyalgia is among the most common and well-documented manifestations of Gulf War Illness (GWI), a presumptive condition under 38 CFR § 3.317 for Gulf War veterans. GWI and fibromyalgia share central sensitization as the core pathophysiological mechanism: chronic neuroinflammation from exposure to organophosphates, sarin, pesticides, and depleted uranium dysregulates central pain processing by permanently altering spinal cord dorsal horn wind-up mechanisms and reducing descending pain inhibition via the periaqueductal gray-rostral ventromedial medulla pathway. Research by Robert Baraniuk and others at Georgetown has documented neuroinflammatory cytokine elevation in cerebrospinal fluid of GWI patients, confirming the neuroimmune basis shared with fibromyalgia. Studies of Gulf War cohorts document fibromyalgia prevalence 2–4 times higher than matched civilian controls.

Key Studies

Baraniuk JN et al. (2013) PLOS ONE (GWI and cerebrospinal fluid proteomics); Ablin JN & Buskila D (2013) Curr Rheumatol Rep (GWI and fibromyalgia); Clauw DJ & Engel CC Jr (2006) Curr Rheumatol Rep (functional pain disorders in Gulf War veterans); Institute of Medicine (2010) Gulf War and Health Vol. 8.

Filing Tips

Fibromyalgia may already qualify as a stand-alone presumptive under Gulf War illness provisions. However, if it is not yet service-connected, filing it as secondary to an already service-connected GWI-related condition provides an additional pathway. American College of Rheumatology 2010 diagnostic criteria (widespread pain index + symptom severity scale). Rheumatology records. Gulf War veterans should consult a VSO about both direct presumptive claims and secondary claims to maximize all available pathways. Fibromyalgia rated at 10–40% based on functional impairment and musculoskeletal examination findings.

How do I file a secondary service connection claim?

File VA Form 21-526EZ and list the secondary condition as a new claimed disability, noting it is secondary to Chronic Fatigue Syndrome (CFS/ME). Submit a nexus letter at the time of filing — the VA does not request nexus evidence on your behalf. An effective date of Intent to File (VA Form 21-0966) protects your start date for up to 12 months while you gather medical evidence.

Common Questions About Secondary Service Connection

What is a secondary service-connected condition?

A secondary service-connected condition is a disability that is proximately caused or chronically worsened by an already service-connected condition. The VA rates secondary conditions separately and combines them with the primary rating using the combined ratings table under 38 CFR § 4.25.

What legal standard applies to secondary service connection?

38 CFR § 3.310(a) governs secondary service connection. It states: "Disability which is proximately due to or the result of a service-connected disease or injury shall be service connected." Aggravation claims — where the primary condition worsens a pre-existing disability — are covered under § 3.310(b).

Which secondary conditions are most common after Chronic Fatigue Syndrome (CFS/ME)?

The 1 secondary conditions documented for Chronic Fatigue Syndrome (CFS/ME) vary by evidence strength. The most strongly supported include: Fibromyalgia (Gulf War-Associated). Evidence strength reflects the volume and quality of medical literature linking each secondary to the primary condition.

What evidence proves a secondary condition is caused by the primary?

The most reliable evidence is a private nexus letter from a treating physician or independent medical examiner that: (1) acknowledges the service-connected primary condition, (2) diagnoses the secondary condition, and (3) states to at least a 50% probability ("as likely as not") that the primary caused or aggravated the secondary. Treatment records documenting the progression are supporting evidence, not a substitute.

How does the VA rate secondary conditions?

Secondary conditions are rated under the same 38 CFR Part 4 diagnostic codes as any other condition. The VA then combines the primary and all secondary ratings using the combined ratings formula under § 4.25 — not simple addition. For example, a 50% primary and a 30% secondary combine to 65% (rounded to 70%), not 80%.

How do I file a secondary service connection claim?

File VA Form 21-526EZ and list the secondary condition as a new claimed disability, specifically noting it is secondary to your already service-connected primary condition. Submit a nexus letter and all relevant treatment records at the time of filing. If your primary claim is already decided, you can file for the secondary as a new claim at any time — the effective date will be the date of the new claim.

Can I add secondary conditions to an existing claim after it has been decided?

Yes. Secondary conditions can be added at any time as a new claim. The effective date for the secondary will generally be the date VA receives your new claim (or the date of an Intent to File, if filed within the preceding 12 months). If the secondary was improperly denied in an earlier rating decision, a Supplemental Claim or Higher-Level Review may allow an earlier effective date.

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