How long do hangovers last? Plus, why yours could be getting worse with age according to an NHS GP

How long do hangovers last? We've all woken up with a heavy head asking this question after one too many the night before. 

Much like everything to do with the body, everyone is different when it comes to how they respond to alcohol. We all know someone who can have drink after drink, only to wake up feeling fresh in the morning, and others who have stopped drinking entirely thanks to awful hangovers. There's no set answer to how long hangovers last, but there are certainly some commonalities in what makes them so bad for some people. 

While everyone sets out with the best of intentions for mindful drinking, it's easy to slip up. This is what an NHS GP wants you to know about how long hangovers last, and the biggest contributors to the worst symptoms.

How long do hangovers last? 

The average hangover lasts for about 24 hours, according to research from Brown University. 

A hangover is defined by a set of negative symptoms that occur normally as a result of drinking too much. These symptoms—including headaches, nausea, digestive issues, and sleep problems—tend to begin as your blood alcohol level begins to fall in the hours after drinking, and they hit their peak when that level hits zero, continuing for between 12 to 23 hours afterward. 

Some people report experiencing a two day - or even a three day - hangover, but there's little evidence to support that this could be the case due to alcohol consumption alone.

How you experience what it is to have a 'hangover' depends on how much you drink and a combination of other factors, such as hydration, blood sugar levels, age, and genetics. 

What causes hangovers?

Several factors contribute to the cause of a hangover, but the catalyst for severe hangover symptoms is poor timing. This is because the time a hangover will last all depends on how quickly your body can work through the alcohol. 

So why do some hangovers last longer than others? 

1. You just drank too much

You’ll get a hangover if you drink too much alcohol, but ‘too much’ is different for every person. It all depends on how quickly your liver can process ethanol, the chemical name for alcohol. 

“To eventually get rid of ethanol from our bodies, we break it down into waste products and it’s these waste products which are largely responsible for the symptoms of a hangover,” explains Dr Daniel Gordon, a Doctify-reviewed NHS and private GP in London.  

“The variation in hangovers people get isn’t fully understood but is likely due to several factors largely connected with the speed at which we metabolize (break down) the alcohol,” he adds. “Anything that affects your metabolism, such as your weight, gender, or even having certain medical conditions or taking certain medications can influence the severity of a person’s hangover symptoms.” 

2. You drank darker spirits

Other substances can contribute to hangover symptoms apart from ethanol. “Darker spirits have higher levels of chemicals called congeners, which are produced during fermentation. While congeners contribute to the taste of the drink, they are also thought to be associated with worse hangover symptoms.”

For example, another study from Brown University found that drinks high in congeners didn't contribute to hangover symptoms specifically, like causing a headache, but those who drank bourbon (which is high in congeners) had worse hangovers overall. 

So if you want to try and avoid a hangover in the future, opt for lighter spirits like gin or vodka over whisky or rum, white wine over red. You could also opt for drinks with a lower ethanol content, like low alcohol wine.

3. You didn't rebalance your electrolytes

Hangover symptoms don't need to be caused directly by alcohol. Dehydration is often one of the most common reasons we tend to feel unwell after drinking, as a study from Kyushu Dental University explains. 

Alcohol is a diuretic, meaning it helps to remove water from the body faster. After drinking too much, some people also sweat more, vomit, and experience digestive issues like diarrhea, all of which cause the body to lose fluid.

When we're dehydrated, symptoms typically match up to and can make a hangover, according to the NHS. As well as having dehydrated skin that feels dry and tight, they typically include:

• Feeling thirsty
• Producing a yellow, strong-smelling urine
• Feeling dizzy or lightheaded
• Feeling tired
• Having a dry mouth, lips and eyes
• Only urinating a little bit (fewer than 4 times per day)

The only hangover cure is drinking less to begin with, but there are ways to combat the effects of drinking that may otherwise make you feel ill in the morning. 

Drinking a litre of water before bed will certainly help, but when we lose liquid we actually lose electrolytes. These, research from The Union Memorial Hospital explains, are responsible for maintaining chemical reactions in the body, including impulse responses and muscle contractions, and balancing fluid levels. To rebalance them, you could drink a sports drink like Lucozade or Powerade, or use a rehydration powder. 

4. You didn't get enough sleep

While drinking certain types of alcohol can make you feel sleepy, overall drinking is more likely to prevent you from getting a good night's sleep and disrupt your bedtime routine. According to research by E.P. Bradley Sleep and Chronobiology Laboratory, drinking up to three alcoholic drinks can make you fall asleep fast, but it ultimately leads to more sleep disruption throughout the night. 

This, the study explains, is because alcohol suppresses the production of melatonin in the body by up to 19%. Melatonin, the hormone that the brain produces when it gets dark, is essential for sleep as it controls the timing of the body's circadian rhythms, which is the internal clock that tells us when it's time for sleep. 

This means that you're more likely to wake up feeling tired and lethargic, contributing to symptoms of a hangover—even if you've not had that much to drink.

5. You have low blood sugar

Similarly, if your blood sugar is low, you're more likely to feel the effects of drinking alcohol. One of the main components of alcoholic drinks is sugar, used in the fermentation process to turn ethanol into beer, wine, or spirits. 

When you drink, your levels of insulin (the hormone that allows your body to use sugar from carbohydrates for energy) spike due to the excess sugar that's entered your bloodstream, according to the National Institute on Alcohol Abuse and Alcoholism. As your alcohol and insulin levels drop back down to normal, you may experience low blood sugar levels—also known as hypoglycemia.

Typical symptoms of hypoglycemia include:

• Profusely sweating
• Feeling tired
• Feelings of dizziness
• Feeling hungry
• Lips tingling
• Feeling shaky or trembling
• Heart palpitations 
• Becoming easily irritated, tearful, anxious or moody
• Rapidly turning pale

So even if what you were drinking wasn't particularly high in alcohol, you could be experiencing a 'sugar hangover', alongside regular hangover symptoms, if the drinks were particularly sugary. 

6. You're genetically more prone to hangovers

"We also know that genetic factors play a role in how we break down alcohol," says Dr Gorgon. 

"Many East Asian people carry a gene which helps control the speed at which alcohol is broken down in the body into acetaldehyde, one of its waste products. Compared to people without this gene, they are much more likely to suffer from more severe symptoms of drinking alcohol, like facial flushing and nausea," he says. 

Why do hangovers get worse with age?

“There aren’t many strong scientific studies into the reasons why hangovers worsen with age, but it’s likely that many different factors are involved,” says Dr Gordon. 

“Much of it is likely due to the way our bodies change in size and shape as we age. For example, as we get older we tend to lose muscle mass and replace it with fatty tissue. Alcohol spreads throughout the body, especially into fat, so an alcoholic drink will tend to cause more symptoms in a body with a higher proportion of fatty tissue,” he says.

Another factor may be that our liver simply has a reduced ability to cope with waste products, which are formed during the breakdown of alcohol in the body. “The waste products stick around for longer and contribute to a longer or more severe hangover.”

How much alcohol can you drink without risking a hangover?

Evidence from the Boston University School of Public Health would suggest, largely, you can avoid a hangover if you only have one or two drinks. This is unlikely to elevate your blood alcohol content to a level where it would come back down substantially, so giving you the symptoms of a hangover. 

However, everyone has a different alcohol tolerance level and susceptibility to the other factors that make up a hangover, so it's not really possible to say for certain.