The Federal Consumers' Union advises avoiding the use of sprays, medications or inhalations citing the risk of allergies. The National Medicines Safety Agency does not recommend vasoconstrictor medications in oral form.
Despite their decongestant qualities, plants used such as thyme, eucalyptus, camphor and even menthol contain terpenes. For UFC-Que Choisir, these natural organic compounds can “generate allergies and convulsive seizures”