The fruit is definitely forbidden

Somewhat unsurprisingly, the apple-like fruit that grows on the manchineel's branches has a very sweet smell, and looks harmless enough to the naked eye.

However, even a couple of bites immediately create an intense burning sensation in the mouth, as well as blisters and swelling in the throat. These effects can last for multiple hours and in some cases the consumption of the plum-sized fruit can also lead to death from severe vomiting and diarrhoea that fatally dehydrates the body.