An epidural is a teeny tiny catheter -- about the size of a piece of fishing line -- that is inserted into your lower back and delivers numbing pain medication to your lower body. In 99 percent of epidurals, the same combination of drugs is used: Bupivacaine, which is a local anesthetic, meaning that it numbs the body at the site at which it's applied, and Fentanyl, a narcotic that blocks the ability for the nerves in your lower body to signal pain to your brain.
The epidural itself only takes a few minutes. You'll either sit up or lie on your side, and will likely be asked to curl your back so that your spine is more visible. An anesthesiologist will clean off a spot on your lower back with a cold solution. Next, a small needle will be inserted into the spot -- this is to numb the skin where the catheter will go in. "This part stings for five to ten seconds, and it's the worst part of the whole thing," says Richard Siegenfeld, M.D., author of The Epidural Book: A Woman's Guide to Anesthesia for Childbirth. Finally, the catheter is inserted. You might feel slight pressure as it goes in, but it shouldn't hurt.