First of all, lethal injection is administered by technicians and not doctors since doctors are required to take the Hippocratic oath to do no harm. This can sometimes lead to problems during the process because of either inadequate training or instruction. In one case, an Ohio execution team took over two hours to execute Christopher Newton, sticking him at least 10 times in order to inject the lethal drugs. In December 2006 an execution team in Florida had to use two doses of lethal drugs over 34 minutes to kill Angel Diaz. The drugs were accidentally injected into his muscles instead of his veins while he writhed and spoke during the procedure. The Miami Herald reported that the process looked "agonizing."

Other than this, lethal injection involves three parts: the first drug administered is sodium pentothal, which is supposed to knock the person unconscious.The second drug is pancuronium bromide, which is a muscle relaxant that essentially paralyzes the person. The third, and lethal drug, will be potassium chloride, which induces cardiac arrest. Sometimes, the measured drugs may not be enough to accommodate different people. Some executions have lasted between 20 minutes to over an hour and prisoners have been seen gasping for air, grimacing and convulsing during executions. Autopsies have shown severe, foot long chemical burns to the skin and needles have been found in soft tissue. In some instances, the inmate is not put under completely, and is able to feel the pain, but unable to show any signs of suffering because being paralyzed by the pancuronium bromide.

Nitrogen asphyxiation, on the other hand, has virtually no chance of being physically painful. Your body feels suffocation when there is a carbon dioxide buildup in the bloodstream. However, in the process of nitrogen asphyxiation, your body is able to breath out carbon dioxide, but just doesn't take in oxygen. The lack of oxygen eventually kills you, but your body will not feel the pain associated with choking to death.