Eucalyptus (particularly Eucalyptus globulus) has a long history of use for respiratory and sinus support, both in traditional medicine and increasingly in scientifically investigated contexts. The primary active component, eucalyptol (also known as 1,8-cineole), has demonstrated mucolytic (mucus-thinning), anti-inflammatory, and mild antimicrobial properties in laboratory and clinical studies. Several clinical trials have evaluated standardized cineole preparations in patients with sinusitis and other respiratory conditions. For example, a 2004 randomized, double-blind, placebo-controlled trial (Kehrl et al., 2004) found that patients with acute non-purulent rhinosinusitis who took cineole experienced significantly reduced symptoms compared to placebo. Other studies have supported the use of eucalyptus oil inhalation or topical preparations for symptomatic relief of nasal congestion, though robust evidence for long-term benefit or for chronic sinus conditions is more limited.

Eucalyptus oil is commonly included in over-the-counter decongestant rubs and inhalants, and its use is recognized by authoritative bodies such as the German Commission E for “catarrhs of the respiratory tract.” However, care must be taken due to potential toxicity if ingested or used inappropriately, especially in children. In summary, while eucalyptus does not cure sinusitis, there is moderate scientific evidence supporting its use for short-term relief of sinus congestion and associated symptoms.