A hangover refers to symptoms that result from drinking alcohol, usually the next day. There is no absolute cure, but people can take steps to relieve many of the symptoms.
Drinking alcohol causes a hangover for a number of reasons, including dehydration, electrolyte imbalances, poor sleep, and inflammation.
The severity of a hangover is closely linked to how much alcohol the person has consumed and how much sleep they have had.
It is not possible to make a general prediction about how much alcohol leads to a hangover. The association depends on individual and situational factors, including sleep, hydration, and the pacing of alcoholic drinks.
In this article, we explore the causes of hangovers and how to reduce the symptoms. We also look at factors that influence their severity.
While there is no absolute cure for a hangover, people can reduce the symptoms by getting plenty of sleep, drinking water, eating nutritious foods, and restoring electrolytes.
Taking over-the-counter nonsteroidal anti-inflammatory drugs (NSAIDs) can help relieve inflammation. This may help with headaches, digestive discomfort, and body aches.
A hangover has to run its course. This involves the body regulating itself as the alcohol leaves the bloodstream.
In the vast majority of cases, hangover symptoms resolve after about 24 hours.
The following may help reduce the symptoms:
- Drinking water: Alcohol makes a person urinate more frequently, often leading to dehydration, in which case it is crucial to rehydrate the body.
- Eating nutritious foods: Healthful foods give the body fuel, nutrients, and antioxidants, which can aid recovery.
- Eating bland foods: When a hangover involves stomach trouble, try bland foods that raise blood sugar levels, such as bread.
- Eating fruit: The fructose in fruit may help the body break down alcohol.
- Resting: Sleep can help speed up recovery.
- Taking medication: NSAIDs, antacids, and some pain relief medications can relieve hangover symptoms.
A person with a hangover should not take pain relief medications or any other drugs that contain acetaminophen. This ingredient can strain the liver — like alcohol — so it is important to avoid combining the two.
Many so-called hangover cures are ineffective. Among these are the “hair of the dog” approach, which involves drinking more alcohol to relieve a hangover. Healthcare professionals do not recommend this method, which may only prolong the symptoms.
The symptoms of a hangover generally start when blood alcohol levels drops considerably. This usually happens the morning after drinking.
Symptoms of a hangover include:
- bloodshot eyes
- excessive thirst
- a headache
- body aches
- sensitivity to light and sound
- bad breath, known as halitosis
- excess saliva, known as hypersalivation
- trouble concentrating
- low mood
- a fast heartbeat
- nausea, vomiting, or diarrhea
- trembling or shaking
If hangover symptoms are severe — during or after a bout of drinking — the person may have alcohol poisoning. This is a medical emergency.
If anyone has the following symptoms of alcohol poisoning, seek medical aid as soon as possible:
- irregular breathing
- slow breathing, or fewer than 8 inhalations per minute
- a low body temperature
- very pale or blue-tinged skin
- continuous vomiting
- fits or seizures
The symptoms of alcohol poisoning can vary in severity. Some people experience certain symptoms more severely than others.
Drinking alcohol causes a hangover for the following reasons:
- Dehydration: Alcohol is a diuretic — it makes a person urinate more, which can lead to thirst, lightheadedness, and other symptoms of dehydration.
- Immune system response: Alcohol can trigger an inflammatory response from the immune system, and this can affect appetite, concentration, and memory.
- Stomach irritation: Alcohol increases the production of stomach acids and slows the rate at which the stomach empties — a combination that can cause nausea, vomiting, and other digestive issues.
- A drop in blood sugar: When a person drinks alcohol, their blood sugar levels can plummet, resulting in shakiness, moodiness, fatigue, general weakness, and even seizures, in some cases.
- Dilated blood vessels: Alcohol consumption can cause the blood vessels to dilate, which can cause headaches.
- Poor quality sleep: Alcohol can cause sleep to be broken or shallow, which can intensify hangover symptoms and contribute to fatigue, brain fog, and low mood.
- Congeners: These byproducts of fermentation are responsible for most of the taste and aroma in distilled drinks such as whiskey and gin, and they contribute to hangover symptoms.
- Toxic byproducts: When the body breaks down alcohol, this produces toxins that can cause or exacerbate many hangover symptoms.
The body needs time to process alcohol. Drinking more alcohol before the body has been able to process the alcohol already present increases the likelihood of a hangover.
The only way to prevent a hangover is to avoid alcohol entirely or drink in moderation, giving the body plenty of time to process the alcohol before consuming more.
Each person’s tolerance level is different, so “moderation” likely varies somewhat from person to person. Tolerance is based on genetics, body type, sex, and other factors.
In addition, a person can limit the risk of a hangover by drinking plenty of water alongside any alcoholic beverages or eating a meal after drinking alcohol.
The Centers for Disease Control and Prevention (CDC) warn against drinking more than:
- one drink per day for females
- two drinks per day for males
What qualifies as one drink may be:
- a 12-ounce (oz) bottle of beer
- a 5-oz glass of wine
- 8 oz of malt liquor
- 1.5 oz of spirits or liquor
While there is no cure for a hangover, there are many ways to reduce or relieve the symptoms.
It is important to stay hydrated, eat nutritious food, and get plenty of rest. Most hangovers pass within 24 hours.