From “Ask Dr. Ly” in the Summer 2007 “Maui Family magizine”
Q. Mangoes are known to give some children itchy rashes. How do I know if my child has one and what can I do for it?
A. Mango itch is usually due to the sap or the skin of the fruit. The rash usually presents as an itchy red area that progressed into fluid-filled blisters that itch and ooze. This is what dermatologists call and acute allergic contact dermatitis. Symptoms typically develop several hours after exposure, but build to a peak within 2-5 days. This why sometimes people dont think the culprit was the mango because the picking was a few days ago. The rash, if not severe, clears up in about three weeks.
Luckily, mango flesh has very low levels of Urushiol, so most sensitive people can eat the fruit as long as someone else peels the mango. Its important to note that the sap can be picked up in a friendly touch through contact with sap residue on a knife handle, furniture, or even by petting a dog/cat that has been touched by someone with sap on their hand. The compound in the sap of the mango is Urushiol, which is the same toxin found in poison ivy and poison oak. Other sources of urushiol are Ginkgo, Japanese Lacquer, Rengas tress, Pink peppercorns and Cashew shell oils.
The sap from mango stems (esp. freshly picked) and the peel need to be washed off thoroughly with soap and water as soon as possible after exposure. Mango itchers should also wash off their bodies as well due to the possibility of incidental contact. A product called IvyBLock (available over the counter) can be used to create a barrier between urushiol and skin so minimize exposure before it happens. There is also a medicinal soap over the counter called Zanfel that can help to cleanse the area. If the rash is not too intense, you can try Cortaid 10 or over the counter cortisone 1%. Often, if the symptoms are serious (e.g. severe itchiness, oozing rash, infection, etc.) it may require medical attention. Prevention is always preferable, so make sure those around you know the mango story.