A hangover is your body’s reaction to alcohol. You feel a throbbing headache, nausea, deep fatigue, sensitivity to light and sound, dry mouth, and sometimes dizziness or irritability. These symptoms come from dehydration, inflammation, disrupted sleep, and the buildup of toxic byproducts as your body processes alcohol.
How Do Hangovers Feel Every Symptom Explained?
A hangover typically brings a combination of several uncomfortable sensations at the same time. You may have a pounding headache, especially in your forehead or temples. Your stomach may feel queasy or upset. You feel exhausted even if you slept for hours. Bright lights and normal sounds seem too intense. Your mouth and throat feel dry, and you are thirsty. Some people feel lightheaded, dizzy, or irritable. These symptoms are not random — each one has a specific cause tied to how alcohol affects your brain, stomach, blood vessels, and fluid balance.
What Causes a Hangover?
Alcohol is broken down in your liver into a compound called acetaldehyde. This substance is toxic and triggers inflammation throughout your body. Alcohol also dehydrates you because it stops your body from making a hormone that normally holds onto water. You lose more fluid than you take in. Your sleep is disrupted even if you think you slept well — alcohol prevents deep and REM sleep. Blood sugar drops, blood vessels widen, and your immune system can become activated. All of these changes together create the feeling of a hangover.
Why Hangovers Cause Headaches
Alcohol widens blood vessels in your brain. This widening, combined with dehydration and inflammation, puts pressure on nerves. The result is a throbbing headache that can be felt on both sides of your head or focused in the temples. Your body also makes more prostaglandins — chemicals that cause pain and inflammation. This is why hangover headaches often feel similar to tension headaches or migraines.
Why Hangovers Cause Nausea and Stomach Problems
Alcohol irritates the lining of your stomach and increases acid production. This irritation can make you feel queasy or even vomit. Your digestive system also slows down, which can cause bloating and discomfort. The buildup of acetaldehyde adds to the nausea. Some people also have diarrhea because alcohol speeds up the movement of food through the intestines. These stomach symptoms are common and usually fade as your body clears the alcohol and its byproducts.
Why Hangovers Cause Fatigue and Brain Fog
Alcohol interferes with your sleep cycle. You fall asleep faster, but you spend less time in the restorative stages of sleep. Your brain does not get enough rest, so you wake up feeling tired. Your blood sugar can also drop after drinking, which leaves you feeling weak and foggy. Alcohol affects neurotransmitters that help you think clearly, so concentration and memory often feel slow during a hangover.
Why Hangovers Cause Sensitivity to Light and Sound
Alcohol makes your nervous system more sensitive. During a hangover, your brain is recovering from the depressant effects of alcohol. This rebound overstimulation can make normal light and sound feel uncomfortable or painful. The inflammation in your body also contributes to a general feeling of being overwhelmed by sensory input. Some people find that wearing sunglasses or staying in a dark, quiet room helps.
Why Hangovers Cause Thirst and Dry Mouth
Alcohol is a diuretic — it makes you urinate more often. Each drink causes you to lose more water than you take in. You lose not only water but also electrolytes like sodium, potassium, and magnesium. The result is a dry mouth, intense thirst, and sometimes a headache made worse by dehydration. Drinking water before, during, and after alcohol can reduce this symptom, but it may not prevent all the effects of fluid loss.
Why Hangovers Cause Dizziness and Vertigo
Alcohol affects the fluid in your inner ear, which helps control balance. Dehydration also lowers your blood volume, which can cause a drop in blood pressure when you stand up. This combination can make you feel lightheaded, dizzy, or like the room is spinning. Your brain is also slower at processing balance signals during a hangover, which adds to the unsteady feeling.
Why Hangovers Affect Your Mood
Alcohol changes the levels of chemicals in your brain that regulate mood, including serotonin and dopamine. When the alcohol wears off, these levels can fall below normal, leading to feelings of anxiety, irritability, or sadness. Some people call this “hangxiety.” The physical discomfort and poor sleep also make it harder to cope with stress. These mood changes usually resolve as your body returns to its normal chemical balance.
What Helps a Hangover
Time is the only real cure — your body needs to process the alcohol and recover. Drinking water can help rehydrate you. Eating a light meal may help restore blood sugar. Ibuprofen or aspirin can reduce headache and body aches, but avoid acetaminophen (Tylenol) because it can stress your liver when alcohol is still in your system. Get rest. There is no evidence that “hair of the dog” (drinking more alcohol) helps — it only delays the recovery. No supplement or special drink has been proven to cure a hangover faster than time and hydration.
Frequently Asked Questions
How long does a hangover last?
Most hangovers last between 8 and 24 hours. The worst symptoms usually peak when your blood alcohol level returns to zero and slowly improve as your body rehydrates and clears inflammation.
Can you prevent a hangover by eating before drinking?
Eating a meal before drinking can slow alcohol absorption and reduce the severity of a hangover. However, it does not prevent hangovers entirely because alcohol still causes dehydration, inflammation, and sleep disruption.
Why do some people not get hangovers?
Genetics, age, and drinking habits all play a role. Some people’s bodies break down alcohol more efficiently or produce less acetaldehyde. Younger people tend to recover faster, but no one is completely immune.
Is it safe to take pain relievers for a hangover?
Ibuprofen or aspirin are generally safe for hangover headaches if taken with food and water. Do not take acetaminophen (Tylenol) because it can damage your liver when combined with alcohol still in your system.
