The steam distillation of eucalyptus leaves is known to generates an oil rich in 1,8-cineole which is a primary active ingredient. A clinical study showed that five minutes of inhalation resulted in the sensation of cooling and increased nasal airflow (Burrow, Eccles et al. 1983). Eucalyptus preparations have been studied as a nasal decongestant during acute infectious rhinitis when applied in conjunction with camphor, menthol, or steam, with improvements in symptoms.

Menthol, known for its cooling effect, is commonly used as a topical therapy for rhinitis by targeting the "transient receptor potential channel melastatin 8" receptor in nasal mucosa. Found in lozenges, nasal sprays, vapo-rubs, inhalers, and cough syrups, menthol is widely used to treat rhinitis linked to upper respiratory infections and allergies. Traditionally utilized in Asia for respiratory ailments, menthol entered Western medicine in the late 19th century. The discovery of its receptor on sensory nerves has advanced menthol's status from herbal medicine to molecular pharmacology.

Thymol in an animal model, hesperidin and thymol were effective in suppressing nasal allergic symptoms and inflammation.(Kilic, Sakat et al. 2019)

Camphor is well established that mucus clearance is impaired nasal and bronchial disorders that has been shown to improve in patients using camphor through inhalation. (Hasani, Pavia et al. 2003)