How long can a person live without food and water or air?

First comes thirst. You'll start to feel thirsty after losing about two percent of your body weight. Before unconsciousness occurs, the kidneys start to shut down. There isn't enough fluid to produce urine, so most people stop feeling the need to urinate. Attempting to do so anyway can result in a burning sensation in the bladder and urethra. Lack of water causes cracked skin and a dry, raspy cough. Coughing won't be the worst, though. While you might be out of fluids, that won't prevent vomiting.