Synopsis

Source of validity: Traditional
Rating (out of 5): 2

Onion (Allium cepa) has a long history of use in traditional medicine for treating coughs and respiratory ailments. Across various cultures, especially in folk remedies throughout Europe, Asia, and the Middle East, onions are used in home preparations such as onion syrup, onion tea, or even sliced raw onions placed near the patient. The traditional rationale is that onions possess expectorant properties—helping to thin mucus and facilitate its expulsion from the airways, possibly due to their sulfur compounds and volatile oils.

Scientific studies specifically evaluating onion's efficacy in treating cough are limited and mostly preclinical. Some laboratory research suggests that onions contain compounds like quercetin and sulfur-containing molecules with anti-inflammatory, antioxidant, and mild antimicrobial effects, which could theoretically help with respiratory symptoms. However, clinical trials in humans are lacking or of poor quality, and no major medical guidelines endorse onion as an evidence-based treatment for cough.

In summary, the use of onion for cough is primarily justified by tradition rather than robust scientific validation. While onions have some biologically active compounds, current evidence supporting their use for cough relief in humans is weak, and onion-based remedies should be considered complementary rather than primary treatments.

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