Is Stuhlprobe useful for allergy?

Whether a stool sample (Stuhlprobe) is useful for allergy is not well supported by current evidence. Stool tests are primarily used to analyze the gut microbiome, and there is some research linking gut dysbiosis to allergic conditions (e.g., atopic dermatitis, hay fever). However, the evidence is weak: most studies are observational, small, and do not prove causation. Commercial microbiome tests are not validated for allergy diagnosis. Standard allergy diagnostics rely on IgE blood tests, skin prick tests, and elimination diets. A stool test may provide additional context about gut health but cannot diagnose allergies or replace medical evaluation. False positives are common in direct-to-consumer tests. Therefore, for anyone with allergy symptoms, consulting an allergist is essential. The evidence grade for stool testing in allergy is 'unclear' or 'marketing'.