Alcohol and upset stomach go hand in hand for many people, especially the morning after a night of heavy drinking. Other symptoms of a hangover from drinking may include vomiting, headache, dizziness, anxiety, and tremors. Alcohol can cause an upset stomach because of a by-product called acetaldehyde, which is produced as the body digests the ethanol in the alcohol. Stomach upset may also be the result of dehydration caused by drinking.
Acetaldehyde is a poisonous substance in alcohol. It is what causes the affects of drinking because it depresses the central nervous system, leading to impairments such as giddiness, loss of inhibition, loss of balance, and slurred speech. This substance is also what causes vomiting if too much alcohol is consumed, as the body needs to rid itself of the toxin forcibly. Acetaldehyde affects the brain, liver, and stomach. One reason alcohol and upset stomach are related is that the toxin irritates the lining of the stomach, causing pain, contractions, and heartburn.
If a person drinks alcohol and gets an upset stomach, dehydration may also be the cause. Dehydration is more likely if a person drinks too quickly, or does not drink water or other non-alcoholic beverages along with the alcohol. Hard alcohol is more likely to cause an upset stomach because ample water is needed for the body to process it.
Because alcohol has no nutritional value, it is not broken down and delivered to cells and tissues in the same way food is. Instead, the alcohol is diluted by the water in the blood and delivered directly into the bloodstream. If more alcohol is consumed than the bloodstream can dilute, the body begins to draw water from the organs and brain. This leads to dehydration, which can cause a headache or queasiness.
To avoid getting an upset stomach from alcohol, it is best to drink slowly or alternate alcoholic and non-alcoholic beverages. Depending on body weight and muscle density, it usually takes men about 45 minutes to process a shot of spirits, beer, or a 4-ounce (118.4 ml) glass of wine. Women usually need an hour to clear the alcohol from their systems because their bodies generally contain more fat than muscle, and muscle contains more water. Drinking lots of water is usually an effective way to deal with a hangover accompanied by upset stomach. Eating light snacks may also calm the abdominal contractions.