Evidence supporting the use of: Quercetin
For the health condition: Congestion

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Synopsis

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

Quercetin is a plant-derived flavonoid commonly found in foods like onions, apples, and berries. Its use to support or help treat congestion, particularly in the context of allergies and upper respiratory tract infections, is grounded in its anti-inflammatory and antihistamine properties. Several laboratory and animal studies have demonstrated that quercetin inhibits histamine release from mast cells and basophils, which are key mediators of allergic reactions and nasal congestion. Additionally, quercetin may reduce the production of pro-inflammatory cytokines, potentially easing inflammation in the respiratory tract.

A handful of small human clinical trials have investigated quercetin’s effectiveness for allergy symptoms and upper respiratory health. Some studies suggest that supplementation may modestly reduce symptoms such as nasal congestion, sneezing, and runny nose in people with allergic rhinitis. However, the overall quality of clinical evidence is limited: trials are generally small, sometimes lack rigorous controls, and results are not always consistent. Major medical organizations do not currently recommend quercetin as a primary treatment for congestion.

In summary, while there is scientific rationale and some early clinical evidence supporting quercetin’s use for congestion, especially that related to allergies, the evidence is not robust. More large, high-quality human studies are needed to confirm its efficacy and establish optimal dosing. As such, quercetin may be considered as a supportive or adjunctive measure rather than a primary therapy for congestion.

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