Why do some people just not get hangovers? 

If you’ve got a friend who appears completely immune to the dreaded symptoms of a hangover, they probably have their genes to thank.

Many have heard stories that drinking the same drink throughout the night, drinking slower or matching each alcoholic drink with one of water could prevent hangover symptoms.

But, as many as a fifth of people are just biologically programed to be less effected by the array of symptoms that usually follow a heavy night out — a headache, nausea and vomiting.   

Research indicates it is mutations to three genes that determines how unwell someone feels after consuming too much alcohol.

While some people have only one or two of the mutations – reducing hangover symptoms – those who have the trifecta of all three are unlikely to suffer severe symptoms.

CYP2E1 is responsible for determining how the body breaks down alcohol compounds, even slight changes can expedite the process of removing alcohol from the body.

Changes to the gene can increased the speed of which the body metabolizes alcohol. As a result, it speeds up the process of getting over alcohol’s affect on the body and reduces the time where a person feels hungover.

Another gene, ADH1B, regulates how the body converts alcohol into a substance called acetaldehyde, a byproduct that is released when we drink alcohol.

Acetaldehyde is an organic chemical that causes the feelings of a hangover by accumulating in the liver, causing the associated headaches and nausea as a result.

It is also known to cause potential long-term damage to a person’s body, opening up a risk of chronic disease and organ issues down the line.

Meanwhile, the ALDH2 gene affects how the body encodes an enzyme called ALDH. This enzyme is responsible for clearing toxins and other things out of a person’s system.

This combination of genes allows a person to function better on less sleep and while dehydrated – helping them avoid the hangover. 

The enzyme alcohol dehydrogenase, which metabolizes the ethanol in the substance into acetaldehyde, is the potentially toxic chemical at the center of a hangover.

The body’s reaction to these toxins in the body are what causes the multitude of symptoms that make-up a hangover. 

Prevalence of the organic compound can damage a person’s cell membranes and even cause scar tissue to form in some organs.

A person will urinate more when drinking as their body attempts to remove the toxin from their body. 

It can also trigger inflammation in the immune system, significant drops in blood sugar and irritation of a person’s stomach due to an increase in the amount of acid produced.

The process of the body metabolizing these chemicals can also cause a person to awaken and disrupt their sleep.

As a result, a person will be even more fatigued.

Some people do not experience these symptoms – or when they do so they are not as significant or debilitating. 

This could be because of genetic differences that affect how their body processes and metabolizes alcohol.

Research has largely been carried out on twins as their genetic similarities make them valuable for testing genetic traits. 

A 2014 study on 4,496 pairs of twins found that 45 per cent of the susceptibility and frequency of hangovers in males was determined by genetics, and 40 per cent in females.

The study also reported that the heritability of hangover resistance, that is, having no hangover the morning after being drunk, was around 43 per cent regardless of gender. 

The other half is likely due to external factors such as how quickly a person drinks or whether they eat while they drink.

This means that no matter how much a person drinks, or whatever other behavior they show throughout the night – half of how bad the morning after will be for them is determined by genetics alone. 

The first ever study researching the topic came in 1972, when a team led by Vanderbilt University gathered 13,511 male twins.

For a study published in 2014, researchers analyzed responses to the alcohol-related questions such as ‘How often do you have a hangover?’ that were collected in 1972. 

Their analysis of the data found that the heritability of alcohol intoxication was around 50 per cent and the heritability of hangovers was around 55 per cent.

A large scale 2008 study that gathered data from high schoolers and college students found that around 23 per cent of people likely have the perfect combination of genes that allows them to dodge hangovers.