Rhubarb Toxicity

Food Rhubarb

By: Catherine Angle, DVM
Staff Veterinarian at Pet Poison Helpline

In a recent episode of Modern Family, the fun loving Dunphy family makes a rhubarb cobbler and is informed by the over-achieving Alex that rhubarb leaves are highly toxic.  In case you were considering your own rhubarb baking extravaganza, I’m sad to tell you there is some truth to that statement.

Rhubarb (or Rheum rhabarbarum) leaves contain soluble calcium oxalate crystals and oxalic acid.  Ingestion of sufficient quantities can cause hypocalcemia, tremors, drooling, stomach upset and, if enough is ingested, renal failure.  Rhubarb poisonings were common in Britain during WWI when the plant leaves were recommended as a substitute food source by the British government due to food shortages.

Why do we eat a toxic plant?  It is delicious!  Truth be told the stalk of the rhubarb contains only very small amounts of oxalates and is virtually non toxic.  Even if you are eating the leaves, you would generally need to eat them chronically (as was the case in WWI Britain) or in fairly large quantities (more then 1 lb of leaves at a sitting for an adult) before having a problem.  Occasionally live stock has developed toxicity from grazing on rhubarb patches for many days in a row.  Rarely are dogs or cats interested in the plant since the leaves have a bitter taste.  So if I were sitting in the Dunphy’s kitchen – I would have eaten the cobbler.