Japanese camphor (Cinnamomum camphora) has a long history of use in traditional medicine, particularly in East Asia, for supporting respiratory health, including the sinuses. Historically, camphor has been used topically as an ingredient in balms, ointments, and inhalants to relieve symptoms of nasal congestion, sinus pressure, and cough. The mechanism was generally attributed to its strong, aromatic vapors, which can create a sensation of clearer airways when inhaled. However, while camphor does produce a cooling effect and can transiently relieve the feeling of stuffiness, there is limited scientific evidence that it has any direct physiological action on the sinuses themselves; rather, it is believed to act on sensory nerves to provide symptomatic relief. Clinical studies specifically evaluating camphor’s efficacy for sinus support are sparse and inconclusive. Regulatory agencies such as the FDA caution against internal use due to toxicity risks. In summary, the use of Japanese camphor for sinus support is mainly based on traditional practices, with only weak evidence from modern science to back up these uses. It should be used cautiously and only externally, avoiding ingestion or inhalation of concentrated vapors.