How Long Does a Hangover Last? 24 Hours, Usually

Most hangovers are gone within 24 hours, according to MedlinePlus. NIAAA puts the same window slightly differently and adds the part that surprises people: symptoms peak when blood alcohol concentration returns to about zero, and they can last 24 hours or longer from there.

The clock does not start when you stop drinking

This is the detail that reorganizes everything else. The worst hour is not 2 a.m. and not the moment of the last drink — it is the moment the alcohol finishes leaving. Someone who drank heavily until 3 a.m. and wakes at 8 a.m. still slightly intoxicated has not reached the peak yet, which is why the morning often gets worse before it gets better.

It also explains why volume drives duration. The more you drank, the later blood alcohol reaches zero, and the later the countdown begins.

What the headache does on its own schedule

The head has its own published timing. The International Classification of Headache Disorders requires that a delayed alcohol-induced headache develop 5 to 12 hours after drinking and resolve within 72 hours. So the headache may start before the rest of the symptoms feel severe, and it is allowed to outlast them by a wide margin without becoming abnormal. More on that pattern in hangover headache.

How long the nausea part runs

Nausea usually behaves differently from fatigue. It comes from direct irritation of the stomach lining and increased acid release, so it tends to be worst early, ease once you can keep fluid and plain food down, and fade before the tiredness does. Anything that irritates the stomach again — coffee on an empty stomach, aspirin or ibuprofen, a heavy fried breakfast — can reset it.

Vomiting that will not stop, or that prevents any fluid staying down for hours, is not a stage of a hangover to wait out. That belongs in hangover nausea, along with the overdose signs worth recognizing.

Does it last longer in your 30s?

Popular belief says yes; the published sources do not set different durations by decade. NIAAA gives one window for adults and attributes variation between people to individual differences, not to birthdays. What genuinely changes in a person’s thirties is usually everything around the drinking: less recoverable sleep, medications that were not in the picture at 22, an early commitment the next morning, and less tolerance for a wasted day. Volume drunk remains the single strongest predictor at any age.

What actually lengthens a morning

• How much you drank. The clearest factor, and the one NIAAA emphasizes.
• How much sleep you lost. Fragmented sleep leaves fatigue that outlives the chemistry.
• Whether you ate. Drinking on a full stomach slows absorption and lowers the peak.
• Fluid replacement. It corrects one mechanism out of six — real, but partial.
• Drinking again in the morning. This might briefly mask symptoms and can prolong the malaise.

Beyond 24 to 48 hours

At that point the question changes from how long to what else. Symptoms that keep going past two days, or that reliably lift only when alcohol returns, are worth raising with a clinician. Seek care immediately for confusion, difficulty staying awake, seizures, slow or irregular breathing, or clammy, pale skin — those describe an alcohol overdose, not a long hangover.

This content is informational and does not replace medical consultation, diagnosis, or treatment. See also hangover symptoms and how to cure a hangover.