Gulf War illness / chronic multisymptom

"Gulf War illness" is the everyday name for a group of long-lasting health problems in veterans who served in the Persian Gulf region. In its rules, the VA splits these into two buckets: an "undiagnosed illness" (symptoms that testing cannot tie to any known diagnosis) and a "medically unexplained chronic multisymptom illness" such as chronic fatigue syndrome, fibromyalgia, or functional gastrointestinal disorders like irritable bowel syndrome. The VA looks for objective signs of a "qualifying chronic disability" that appeared during service in the Southwest Asia theater or to a degree of 10% or more by December 31, 2026, and that has lasted 6 months or more (counting periods that come and go). Common symptoms the rules list include fatigue, skin problems, headache, muscle and joint pain, neurological and neuropsychological signs, breathing problems, sleep trouble, stomach and bowel issues, and heart-related symptoms.

There is no single diagnostic code just for Gulf War illness. Instead, the rules say a qualifying chronic disability is rated using the criteria in Part 4 of the rating schedule for a disease or injury that affects the body in a similar way (called rating "by analogy"). For example, fibromyalgia is rated under diagnostic code 5025, where the percentage is driven by how often and how severely symptoms occur: 10% for symptoms that need continuous medication, 20% for symptoms that come and go but are present more than one-third of the time, and 40% for symptoms that are constant or nearly constant and do not respond to treatment. Other clusters are matched to their closest codes (for instance, chronic fatigue syndrome or a functional gastrointestinal disorder), so the rating depends on which symptoms you have and how much they limit you.

The biggest help in these claims is the presumptive pathway. For a covered Persian Gulf veteran, a qualifying chronic disability is treated as service-connected for all purposes, which means you generally do not have to prove a medical "nexus" linking it to service—you only need to meet the service and timing requirements. The VA presumes a connection for veterans who served on or after August 2, 1990, in recognized locations such as Iraq, Kuwait, Saudi Arabia, Bahrain, Qatar, and surrounding areas. Separately, the PACT Act added more than 20 burn pit and other toxic-exposure presumptive conditions for Gulf War era and post-9/11 veterans, expanding who may qualify. This is educational information about how the VA's rules work in general; it is not legal advice or a VA decision, and a denial can be a starting point rather than the end.