a good read:
Euphorbias are among the most poisonous plants on earth. In some species the sap (latex) is so toxic that it can result in blistering, blindness, severe ulceration and burning equivalent to 3rd degree burns caused by fire. Some are so poisonous that merely breathing in the air near a 'bleeding' plant can result in a burning sensation of the mouth and throat. some people experience allergic reactions to the sap further complicating reactions.
In Africa the sap of Euphorbias is used for fish and arrow poisons. They have also been used for homicidal purposes. drinking water contaminated with even dilute concentrations of sap can result in death, thus using the sap as fish poison upstream in a river can kill the people downstream. cows fed on certain euphorbias produce deformed offspring.
and yet we grow and love them! they are an extremely popular succulent genus with collectors. some people collect nothing else. the diversity of this enormous genus is absolutely astounding. many are very attractive plants.
paradoxically, many euphorbias also have medicinal and in some cases even edible qualities. often the same species has both a good and bad use.
it is common to be told of cases involving contact with euphorbia sap resulting in severe burning of the skin and temporary blindness resulting in hospitalisation. and yet some collectors come into contact with the sap on a regular basis and experience only mild, if any, reactions. depends on the sensitivity of the person to the sap.
after you read through these horror stories don't be offput growing these plants. care is all that is required. wash off sap immediately if you come into contact.
my only personal incidents involve minor skin irritations and redness caused by contact with Euphorbia mammillaris and horrida sap. also when i accidently sticked my euphorbia ammak with the spines of a pilosocereus i experienced a dry burning sensation of throat and mouth. what amazed me the most was the tiny quantity of sap present, a few pinpricks worth, and this was outside with good ventilation.
would love to hear of anyone else's tales.