Hangover symptoms typically include headache, nausea, fatigue, thirst, and sensitivity to light and sound. They set in within hours of your blood alcohol level dropping and usually resolve within 24 hours. Most people experience a combination of physical discomfort, mental fog, and mood changes, though the exact mix varies depending on how much you drank, what you drank, and your individual biology.
Physical Symptoms
The most recognizable hangover symptoms are physical. Headache and muscle aches tend to hit first, often alongside extreme thirst and dry mouth from dehydration. Nausea, vomiting, and stomach pain are common because alcohol directly irritates your stomach lining and increases acid production. You may also notice dizziness or a sensation that the room is spinning, a fast heartbeat, shakiness, and sweating.
Sensitivity to light and sound is another hallmark. Your nervous system, which alcohol suppressed while you were drinking, rebounds into a heightened state as the alcohol clears your body. That rebound effect is why even normal room lighting or background noise can feel overwhelming the morning after.
Mental and Emotional Symptoms
Hangovers aren’t just physical. Problems with concentration, decision-making, and thinking clearly are well-documented effects. Your attention and coordination can be noticeably impaired even after alcohol is no longer detectable in your blood.
Mood changes are equally common: depression, irritability, and a distinctive form of anxiety sometimes called “hangxiety.” While you’re drinking, alcohol boosts calming brain chemicals and suppresses alerting ones. When the alcohol wears off, your brain chemistry swings in the opposite direction, leaving you feeling restless and anxious. For most people, this next-day anxiety is strongest in the first 12 to 24 hours. If you already live with anxiety or depression, you’re more likely to experience it intensely.
Why Hangovers Happen
Several overlapping processes drive hangover symptoms. Dehydration and electrolyte imbalances account for the thirst, dizziness, and headache. Alcohol is a diuretic, meaning it makes you urinate more than the volume of liquid you’re taking in.
Your immune system also plays a significant role. Research has found that levels of specific immune-signaling molecules rise significantly during a hangover compared to normal conditions. This immune activation is similar to what happens during a mild infection or inflammatory response, which helps explain why hangovers can make your whole body feel achy and run-down. Nausea, headache, diarrhea, and fatigue during a hangover are all thought to be connected to these immune system changes. Studies have shown that drugs blocking inflammatory compounds can prevent some hangover symptoms, reinforcing the idea that inflammation is a core part of the experience.
Poor sleep compounds everything. Alcohol may help you fall asleep initially, but it disrupts sleep quality later in the night, reducing the restorative deep sleep your body needs. That’s why you can sleep for eight hours after drinking and still wake up exhausted.
What Makes Some Hangovers Worse
The single biggest factor is how much you drank. Hangovers are dose-dependent: more alcohol means more severe symptoms. But the type of alcohol matters too. Research from the Society for the Study of Addiction found that wine was consistently associated with the highest hangover severity, while beer, cider, and spirits were linked to lower severity ratings.
Mixing drink types was associated with poorer next-day productivity and reduced clear-headedness, though researchers found no physiological explanation for why this would be the case. Expectations likely play a role. If you believe mixing drinks will destroy you the next morning, you’re more likely to perceive your hangover as worse.
Other personal factors that influence severity include how much you ate before drinking, your hydration level, your body weight and composition, and your genetics. About 23% of the population appears to be hangover-resistant. This figure has been remarkably consistent across studies, with both survey-based and experimental research landing on nearly the same number. Certain genetic variations in how your body processes alcohol can make hangovers more or less severe, which partly explains why two people can drink the same amount and feel very differently the next day.
How Long Symptoms Last
Most hangovers begin the morning after heavy drinking and resolve within 24 hours. Symptoms typically peak when your blood alcohol concentration hits zero or near-zero, which for most people is sometime the following morning. Mild hangovers may clear up in a few hours; severe ones can linger through the entire next day. Factors like sleep quality, hydration, and food intake during and after drinking all influence how quickly you recover.
Hangover vs. Alcohol Withdrawal
Hangovers and alcohol withdrawal share some overlapping symptoms, including nausea, anxiety, tremors, and sweating, but they are fundamentally different conditions. A hangover is a temporary reaction to a single episode of heavy drinking. Alcohol withdrawal is the body’s response to the sudden absence of alcohol after it has developed a physical dependence.
The key differences are in timeline, severity, and duration. Hangover symptoms appear the morning after drinking and fade within a day. Withdrawal symptoms can start 6 to 12 hours after the last drink in someone with chronic or heavy alcohol use and may last for days. Withdrawal can also produce symptoms that hangovers never do: hallucinations, seizures, and a dangerous condition called delirium tremens, marked by confusion, rapid heart rate, and fever. If symptoms are getting worse rather than better after 24 hours, or if you experience tremors and confusion that intensify over time, that pattern points toward withdrawal rather than a hangover.
When Symptoms Signal Something More Serious
A standard hangover is miserable but not dangerous. Alcohol poisoning is. The line between “very drunk” and “medical emergency” can be hard to see, especially because vomiting occurs in both hangovers and overdoses. The critical warning signs of alcohol overdose include mental confusion or stupor, inability to stay conscious or be woken up, seizures, slow breathing (fewer than 8 breaths per minute), irregular breathing with 10 or more seconds between breaths, clammy or bluish skin, and extremely low body temperature.
One of the most dangerous aspects of alcohol overdose is the suppression of the gag reflex. A person who has passed out and lost this reflex can choke on their own vomit. If someone is unconscious, vomiting, or breathing irregularly after heavy drinking, that is not a hangover in progress. It is a medical emergency.