What role does IgE play in fatigue?

IgE (immunoglobulin E) is primarily involved in allergic responses. Elevated IgE levels can indicate allergies or parasitic infections, which may indirectly contribute to fatigue—for example, through sleep disruption in allergic asthma or chronic low-grade inflammation. However, the direct causal link between IgE and fatigue is weak. Most evidence is observational and associative, not mechanistic. IgE levels are highly variable and influenced by environment and allergen exposure. A consumer IgE test alone cannot explain fatigue. For persistent tiredness, medical evaluation should include iron status, thyroid function, sleep quality, and other common causes. Caveat: direct-to-consumer IgE tests are not diagnostic and may lead to unnecessary worry or false reassurance.