What causes hangovers?

Everyone who has ever had one too many knows the misery of waking up the morning after the night before with a thumping hangover. That combination of headache, nausea, hypersensitivity and gastric upset that we call a hangover is, of course, caused by drinking alcohol.

When you drink alcohol, you take poison into your body. Having a hangover after drinking is nothing more than the after-effects of poisoning. Alcohol poisons people in two ways — physically and psychologically. The physical effects include the familiar headaches, vomiting and nausea.

The psychological effects are subtler and vary from person to person. Alcohol is a depressant drug. Drinking too much is overdosing on a depressant. Your body responds the next day by bouncing back from the depression, becoming hypersensitive. This explains why many people with a hangover are cranky, irritable and easily upset.

The physical effects are the result of the havoc that alcohol causes in bodily systems:

  • Alcohol dehydrates the body. Your liver needs water to dissolve and expel the toxins it receives from alcohol. When the body’s reserves run out, the liver borrows water from other organs, including the brain.
  • Boozing can cause a mild dose of malnutrition, since it strips your body of its storage of vitamins and minerals, and depletes blood sugar. The loss of some of these trace elements can make a bad headache much worse.
  • Some alcoholic drinks contain complex organic poisons, such as methanol and acetone, which many researchers believe could be the instigators of a hangover.
  • In a bad harvest year, wine may contain more impure elements than in other years.
  • Nearly all red wines, and Chardonnay white wines, are matured in wooden barrels. During the first three or so years of a wine’s maturing, many poisonous substances present at bottling are neutralised in the barrel. If these wines are drunk too young, they will have a higher level of toxins and may contribute to a bad hangover.

Which drink is most likely to cause a hangover?

The rule of thumb is that the paler the spirit, the less painful the subsequent hangover. This is due in no small part to tiny toxins called cogeners that are present in alcoholic drinks. The darker the drink, the more cogeners it contains.

A glass of Bourbon whiskey, for example, contains eight times as many cogeners as the equivalent amount of vodka. Tests published in the British Medical Journal discovered that Bourbon was twice as likely as vodka to cause a hangover. It is generally accepted that cheap red wine will cause the worst hangover, followed by brandy, dark rum, whisky, white wine, gin and vodka.

However, drinking too much beer is likely to cause a hangover by dehydrating the body through urination, while drinking alcopops or sweet liqueurs can lead to a hangover by causing nausea.

Mixing your drinks is the most surefire way to procure a hangover.

What is the best way to treat a hangover?

Alcohol can affect different people in many different ways. Some people have a high tolerance level for alcohol, and may feel compelled to drink heavily in order to feel the effect of drinking. Others may react very severely to alcohol, with flushes, rashes or violent vomiting, and may never be able to enjoy a drink.

The only guaranteed way to avoid a hangover is to avoid drinking alcohol, but given the central role of the pub in Irish social life, this advice may be more pious than practical. For those who prefer not to abstain from drinking, alcohol must be treated with respect - and this means moderation.

There are as many hangover cures as there are drinkers, but the best way to treat a hangover is as if it was a severe cold. Rest as much as possible, and rehydrate the body by drinking water. Sweet drinks may help in replacing blood sugar, but may also cause nausea.

Some people always make a point of drinking at least two or three glasses of water just before going to sleep, and swear by this as an effective method of either reducing or even eliminating a hangover after drinking. The effectiveness of this method is that it combats dehydration. It certainly can't do much harm, if you've already drunk quite a lot of alcohol.

Avoid tea and coffee, as they will only dehydrate the body further. Don’t have a "hair of the dog" — it only works by delaying the hangover till later. You simply remain drunk, harm your body further, and will still have to face that hangover eventually!

Back to top of page