When you drink a lot of alcohol you can get a hangover; unpleasant and debilitating effects felt after alcohol consumption that can make you feel ill. When you have a hangover, detoxification of the body is taking place. Symptoms of a hangover include nausea, vomiting, tremors, dizziness, headaches, thirstiness and sweating. This can last for several hours.
A hangover has various causes, most importantly dehydration. The kidneys are stimulated to secrete extra fluids. The result is that you urinate more and more frequently, and therefore dehydrate faster. With spirits, the hangover is even more severe due to stronger alcohols containing less water, unlike weaker alcohols like beer.
Another cause is the conversion of alcohol into the toxic substances ADH (acetaldehyde) and ALDH (alcohol dehydrogenase). This substance is created during the breakdown of alcohol and causes headaches and trembling. The more you drink, the more of these substances are metabolised by your liver.
A third cause for a hangover are fusel alcohols. These are types of alcohol different to regular alcohol, and these toxic substances are broken down at a slower rate. Alcohol irritates your stomach lining, causing you to feel nauseous and to vomit.
Aspects personal to the user also play a role. If you are tired or not feeling well, the hangover will also be worse.