From the US Dept of Veteran Affairs:
A prominent condition affecting Gulf War Veterans is a cluster of medically unexplained chronic symptoms that can include fatigue, headaches, joint pain, indigestion, insomnia, dizziness, respiratory disorders, and memory problems.
VA presumes certain chronic, unexplained symptoms existing for 6 months or more are related to Gulf War service without regard to cause. These “presumptive” illnesses must have appeared during active duty in the Southwest Asia theater of military operations or by December 31, 2016, and be at least 10 percent disabling. These illnesses include:
- Chronic Fatigue Syndrome, a condition of long-term and severe fatigue that is not relieved by rest and is not directly caused by other conditions.
- Fibromyalgia, a condition characterized by widespread muscle pain. Other symptoms may include insomnia, morning stiffness, headache, and memory problems.
- Functional gastrointestinal disorders, a group of conditions marked by chronic or recurrent symptoms related to any part of the gastrointestinal tract. Functional condition refers to an abnormal function of an organ, without a structural alteration in the tissues. Examples include irritable bowel syndrome (IBS), functional dyspepsia, and functional abdominal pain syndrome.
- Undiagnosed illnesses with symptoms that may include but are not limited to: abnormal weight loss, fatigue, cardiovascular disease, muscle and joint pain, headache, menstrual disorders, neurological and psychological problems, skin conditions, respiratory disorders, and sleep disturbances.