The sap which exudes from the stalk close to the base of the fruit is somewhat milky at first, also yellowish-resinous. It becomes pale-yellow and translucent when dried. It contains mangiferen, resinous acid, mangiferic acid, and the resinol, mangiferol. It, like the sap of the trunk and branches and the skin of the unripe fruit, is a potent skin irritant, and capable of blistering the skin of the normal individual. As with poison ivy, there is typically a delayed reaction. Hypersensitive persons may react with considerable swelling of the eyelids, the face, and other parts of the body. They may not be able to handle, peel, or eat mangos or any food containing mango flesh or juice. A good precaution is to use one knife to peel the mango, and a clean knife to slice the flesh to avoid contaminating the flesh with any of the resin in the peel.
The leaves contain the glucoside, mangiferine. In India, cows were formerly fed mango leaves to obtain from their urine euxanthic acid which is rich yellow and has been used as a dye. Since continuous intake of the leaves may be fatal, the practice has been outlawed.
When mango trees are in bloom, it is not uncommon for people to suffer itching around the eyes, facial swelling and respiratory difficulty, even though there is no airborne pollen. The few pollen grains are large and they tend to adhere to each other even in dry weather. The stigma is small and not designed to catch windborne pollen. The irritant is probably the vaporized essential oil of the flowers which contains the sesquiterpene alcohol, mangiferol, and the ketone, mangiferone.
Mango wood should never be used in fireplaces or for cooking fuel, as its smoke is highly irritant.