Synopsis

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

Quercetin is a plant flavonoid found in many fruits and vegetables, and it has been studied for its potential immune-modulating and anti-inflammatory properties. Scientific interest in quercetin for colds stems from its ability to inhibit enzymes and pathways involved in inflammation and viral replication. Laboratory (in vitro) and some animal studies have shown that quercetin may suppress rhinovirus and other respiratory viruses, and inhibit histamine release, which could theoretically reduce nasal congestion and other cold symptoms.

However, human clinical trials are limited and results have been inconsistent. Some small-scale studies suggest quercetin supplementation may modestly reduce the incidence or duration of upper respiratory tract infections, especially in physically stressed individuals (such as athletes), but the effects are generally mild. There is little direct evidence that quercetin acts as a decongestant in humans, and its use for this purpose is not widely supported by large-scale, high-quality clinical trials. The evidence base is thus rated as low to moderate. Quercetin is sometimes included in dietary supplements marketed for immune support, but its specific benefit for treating or preventing colds, or acting as a decongestant, remains unproven according to current scientific standards.

More about quercetin
More about Colds (decongestant)

Other ingredients used for Colds (decongestant)

Other health conditions supported by quercetin

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