Calamus rhizome (Acorus calamus), also known as sweet flag, has a long history of use in traditional systems of medicine such as Ayurveda and Traditional Chinese Medicine. In these traditions, calamus is often recommended for ailments involving the head and sinuses, including headaches and sinus congestion. The rhizome is sometimes used in formulations for inhalation or as a component in herbal teas intended to alleviate such symptoms. The rationale in traditional medicine is often based on the believed ability of calamus to "open the channels" or clear obstructions, and its perceived anti-inflammatory and aromatic properties.

However, scientific evidence supporting the use of calamus rhizome specifically for sinus headache is limited. While some studies have investigated the antimicrobial, anti-inflammatory, and analgesic properties of calamus extracts, these are mostly preclinical (in vitro or animal) studies and do not directly address sinus headache in humans. There are also safety concerns regarding certain compounds (e.g., β-asarone) present in some varieties of calamus, especially with prolonged or high-dose use. No well-designed clinical trials have validated its efficacy for sinus headache. Therefore, the use of calamus rhizome for this condition is primarily justified by tradition rather than robust scientific evidence.