alcohol vestibular system balance dopamine digestion

Why does alcohol make you dizzy?

“How does drinking alcohol lead to lack of balance? What are the physiological processes underlying this phenomenon?”

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Fig 1. Alcohol is often consumed recreationally in doses that make it easy to get very drunk very quickly, such as shots in the image above. (Source: Pixabay by Pologi)

Why do people stumble around drunk? Why do we feel dizzy after a few too many drinks of our favorite alcoholic beverage? Alcohol messes with your equilibrium. This is why the police are able to keep the roads safer with tests of agility and balance. When someone appears to be driving recklessly, they are pulled over and asked to walk in a straight line or go through other tests of balance. This is a test to assess how wobbly the drunk driver may be feeling. But where does that wobbly feeling come from? They just drank alcohol, and the digestive system that the alcohol travels through doesn’t have anything to do with a person’s sense of balance…right?

When your body digests anything, it goes in the mouth, down the esophagus, and gets chemically broken down by acids in your stomach. It then travels through the small intestine and large intestine to reabsorb any nutrients that may be used by your body to produce energy, or for storage when nutrients become more scarce. That which is not useful for you is excreted out the anus (Figure 2) [1]. When nutrients are reabsorbed through the walls of your intestines, they go into your bloodstream to be circulated through your body and put to use where your body needs them most.

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Fig 2. The digestive system labeled in its components. Photo source Wikimedia Commons, by BruceBlaus)

Your liver gets rid of most toxins that you’ve managed to ingest (and alcohol is literally a poison to humans). The liver is located right by the beginning of the small intestine and works to detoxify whatever you have ingested, including alcohol, before it gets sent through your bloodstream and around your body to do damage. This is why alcohol must be consumed in moderation, because the liver can do incredible detoxification for your body but it is a relatively small organ and can only handle so much toxic material at once. If there is an excess in your system at one time, then it cannot be processed properly and will make its way into your bloodstream and travel throughout your body.

Alcohol has a thinning effect on your bloodstream. The human body is 60% water which flows through organs, veins, and even exists in bones [2]. Compared to the usual water heavy density in the bloodstream, the reabsorption of alcohol into the bloodstream leads to a change in density and acts as a blood thinner [3]. But blood isn’t the only fluid in your body that is affected by alcohol thinning.

The human sense of balance is moderated by the vestibular system inside your ears. The vestibular system works by monitoring a special fluid in your ears called endolymph through differently oriented canals, and when the endolymph is thinned by alcohol making its way through your system and into the endolymph, it cannot properly discern where you are in space. Endolymph thinned by alcohol does not move around in the vestibular system’s semicircular canals the same way that it does at its usual density (Figure 3). Therefore, you get a sense that you’re more sideways or disoriented in space than usual because your body’s self-orienting system has been altered by alcohol.

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Fig 3. The vestibular system in humans. These structures are all located inside your ear, with the semicircular canals in three different orientations containing endolymph to let you know your orientation in space. Photo source NASA.

With this side effect in mind, in addition to potential for alcohol poisoning, liver damage, heart disease, stroke, and more, why do people still drink alcohol in excess [4]? There’s always the social component of it, but if we’re purely thinking physiologically, alcohol interacts with dopamine release in the brain [4]. Dopamine is a neurotransmitter linked to feelings of pleasure, so an increase in dopamine from alcohol consumption would reasonably lead to positive associations with drinking…until it becomes excessive and leads to the various life threatening side effects. Everything in moderation…


[1] National Institute of Diabetes and Digestive and Kidney Diseases. 2017. “Your Digestive System & How it Works.” Accessed February 18, 2019.

[2] US Geological Survey. 2018. “The water in you.” Accessed Februrary 18, 2019.

[3] 2019. “The Spins from Drinking Too Much.” Accessed February 18, 2019.

[4] 2018. “Alcohol Acting as a Blood Thinner.” Accessed February 18, 2019.

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