For many taking off on an international flight, ordering a beer, wine or other alcoholic beverages has become a way to celebrate an impending trip, relax on board or even to help passengers fall asleep on a long flight. However, for many, alcohol seems to have a more profound impact on the body up in the air than on the ground – and there’s an explanation for that!

What exactly happens to your body when you drink alcohol on a plane? KLM Royal Dutch Airlines shares some insight into what exactly happens to your body when enjoying an alcoholic beverage in the air.

What happens when you drink alcohol

After drinking an alcoholic beverage what’s known as blood alcohol content (BAC) takes between 30 to 60 minutes to peak and reach its maximum effect. Needless to say, consuming several alcoholic beverages during a short period of time can easily mean you are expecting your body to cope with more alcohol than your liver can process. In such a case the excess alcohol will travel through your bloodstream un-metabolised and unchanged. The concentration of alcohol in the blood, or BAC, will then increase.

As it travels through your bloodstream, the alcohol eventually reaches your brain, where it acts as a sedative and slows down transmissions and impulses between the nerve cells that control your ability to think and move. Although alcohol is a depressant, it also removes inhibitions, which explains the sometimes happy and other times aggressive behaviour associated with drinking alcohol. It also increases the flow of fluid through your kidneys, increasing the likelihood of becoming dehydrated.

What happens when you drink alcohol on board a plane?

During a flight, the barometric pressure in the cabin of a plane is lower than it is in most places on earth. You can compare it with an altitude in the mountains of between 1,800 and 2,200 metres. This decreased pressure environment diminishes the body’s ability to absorb oxygen and it can produce light-headedness. We call this hypoxia. Generally speaking, this is not an issue but the feeling could be similar to the experience you have after drinking alcohol.

Therefore, if you drink alcoholic beverages during a flight you may notice it sooner, and so might the crew and other passengers if you drink too much. In other words, because of the lower level of oxygen in your blood, you may seem more drunk in the air than you would on the ground after consuming the same amount of alcohol. But, in fact, your BAC will show the same percentage as would be the case if you drank the same amount of alcohol on the ground under similar circumstances. A complicating factor is that the air in an aircraft is very dry and, coupled with the diuretic effect of drinking alcohol; you may become dehydrated much faster than you would on the ground.

So, to combat dehydration make sure you drink water with every alcoholic beverage. And minimise your intake of salty food, as this may have an adverse effect by making you more thirsty and encouraging you to drink at a faster rate.

What is KLM’s policy on serving alcohol on board?

Policies on serving alcohol on board differ per airline and destination. At KLM you can prepare for your trip and can even check out the menu (including beverages) of your specific flight beforehand.

The safety, security and comfort of passengers and crew are of the highest priority to airlines. Unruly behaviour or acts by passengers, due to alcohol abuse/intoxication or otherwise, is an infringement of international law. The pilot in command of a flight is authorised to disembark or deliver an unruly passenger to a law-enforcement agency.

So, it’s better to be safe than sorry…and drink wisely on an aircraft.