Sambucus nigra (elderberry) has a long history of traditional use for supporting respiratory health, including sinus-related issues. In recent years, scientific studies have begun to investigate its potential mechanisms and efficacy. The berries and flowers of elderberry contain flavonoids, particularly anthocyanins, which exhibit antioxidant and anti-inflammatory properties. These constituents are thought to reduce inflammation in mucous membranes, such as those lining the sinuses, potentially easing symptoms of sinus congestion and irritation.

Several small clinical trials and laboratory studies have shown that elderberry extracts can modulate immune responses and inhibit the replication of certain respiratory viruses. For example, a randomized, double-blind, placebo-controlled study published in 2004 (Zakay-Rones et al.) found that elderberry extract reduced the duration and severity of symptoms in influenza patients, which often include sinus congestion. However, direct clinical evidence specifically on sinusitis or chronic sinus support is limited, and most research focuses on general upper respiratory tract infections.

Overall, while there is a plausible scientific rationale and some supporting data for Sambucus nigra in supporting sinus health, the evidence is moderate, not robust. Most clinical trials are small-scale and do not isolate sinus outcomes. Therefore, its use is supported by scientific evidence to a moderate extent, but more targeted research is needed to confirm efficacy for sinus-specific conditions.