European Elder (Sambucus nigra) has a longstanding history of use in traditional medicine, particularly for respiratory health, which encompasses sinus support. Traditionally, elder flowers and berries have been used to alleviate symptoms of colds, flu, and sinus congestion, primarily due to their reputed anti-inflammatory and antiviral properties.

Scientifically, several studies have investigated the effects of elderberry extracts on upper respiratory tract infections. Randomized controlled trials have demonstrated that elderberry may reduce the duration and severity of cold and flu symptoms. While these studies typically focus on general respiratory symptoms, including nasal congestion and sinus discomfort, specific research targeting sinusitis is limited.

The proposed mechanisms include the inhibition of viral replication and modulation of inflammatory cytokines, which can theoretically benefit sinus health by reducing mucosal inflammation and congestion. A 2019 meta-analysis concluded that elderberry supplementation could significantly reduce upper respiratory symptoms, though it called for more rigorous studies to clarify its role for specific conditions like sinusitis.

In summary, there is moderate scientific evidence supporting the use of European Elder for general respiratory support, which includes the sinuses, but direct high-quality evidence for sinus-specific conditions is limited. The traditional use is well established, and preliminary scientific research is promising, justifying a moderate evidence rating.