Allergic reactions occur due to a hypersensitivty of the immune system to what it detects as a foreign invader in the body. This can cause similar symptoms to the common cold, such as watery eyes, a stuffy nose and chest congestion. Peppermint tea can quickly counteract some of these symptoms and return your body to normal. As a decongestant, peppermint tea is highly effective in cutting through the phlegm and mucus in the respiratory tracts; then, its role as an expectorant will help you expel those substances, along with the allergic irritants that caused the reaction in the first place!