Castor oil

Kerry
I am 40 weeks 3 days...and in a ton of discomfort. Has anyone tried castor oil? The only negative effects I've seen are diarrhea and dehydration. But I couldn't see any problems with a tea spoon or two to try it- as long as I keep a big bottle of water near by. 
What are your thoughts? I don't want to do anything that would hurt the baby- there may be more to castor oil that I don't know about!
Thank you