 When mango trees are flowering in spring, local people with allergies may experience breathing difficulty, itching of the eyes, or facial swelling, even before flower pollen becomes airborne.In this case, the irritant is likely to be the vaporized essential oil from flowers.During the primary ripening season of mangoes, contact with mango plant parts – primarily sap, leaves and fruit skin – is the most common cause of plant dermatitis in Hawaii.