According to Medline Plus, rhubarb leaves are poisonous and contain oxalic acid and possibly anthraquinone glycosides. Rhubarb leaf poisoning comes from the leaves only; the stalk can be eaten.Know More
To treat an allergic reaction, flush the face, eyes and hands with water if they have come in contact with rhubarb leaves. Some of the symptoms of a rhubarb leaf poisoning include throat and mouth burning, diarrhea, difficulty breathing, stomach pain and eye pain, red-tinged urine, vomiting, seizures, nausea and weakness.
Symptoms that go on one to three days may need hospitalization. Serious cases can lead to kidney failure, and, rarely, deaths are reported.