The next time you have sinus trouble try dissolving some menthol crystals in hot water and then inhale through the sinuses. It is believed to be one of the easiest ways to relieve sinus pressure because it infiltrates the pressure and congestion of the sinus cavities, allowing the flow of air that is entering the lungs to be received easily. This is a common go-to product for those who are sick with the flu, common cold, or even everyday allergies.