Bloating, Headaches and Hangovers: Why Your Body Hates Alcohol

Last Updated:

March 23rd, 2026

Many of us have experienced the odd hangover now and again but have you ever stopped to understand why you might feel so terrible after a night of overindulgence? For many people, a hangover or other effects from drinking are brushed off as a normal consequence of alcohol. Yet when you start to peel back the layers and understand exactly why your body reacts so badly to alcoholism, it can become quite worrying.

What actually is alcohol?

In simple terms, the alcohol we drink is ethanol, which is produced when yeast ferments sugar, converting it into alcohol and carbon dioxide. That same chemical process has been used for thousands of years, long before anyone understood what was happening at a molecular level.

Ethanol, by definition, is a toxic substance, which sounds dramatic, but it’s best understood from a biological angle. It is essentially a poison that the body cannot use for growth, repair or energy in the same way it uses food.

Every time alcohol enters the bloodstream, the body treats it as something that needs to be neutralised and removed as quickly as possible.

The liver takes on the job of dealing with this ‘threat’ and first converts ethanol into acetaldehyde. This compound is even more toxic than alcohol itself, but the process must occur so the body can eventually convert it into acetate and remove it altogether. Along the way, this places stress on multiple organ systems and wreaks havoc on the body and mind.

Understanding the physical effects of alcohol

The last section taught us what alcohol really is and why it’s toxic, but we didn’t focus on the effects it has on the body in detail. This is exactly what this section is for, and here, we’ll explore the specific downsides to alcohol consumption and how these affect the body in the short term and long term:

Disrupted sleep architecture

As many of us have probably tried and error-ed ourselves, alcohol helps us fall asleep faster. While it’s true that alcohol does send us to sleep more quickly, the sleep quality we then endure is awful compared to when we don’t drink.

Studies show that drinking before bed changes how the brain alternates between sleep stages. In fact, it reduces restorative REM sleep and alters the timing of deep sleep. This basically means that the stages of sleep we need the most are altered, and now your body isn’t getting the quality sleep it needs.

These changes lead to symptoms like:

Insomnia
Frequent night-time awakenings
Grogginess the next day
Poor concentration
Poor memory retention

Dehydration

Alcohol is a natural diuretic, which means if you drink enough of it, you’ll notice more frequent trips to the toilet. So, what actually happens here? Science shows that alcohol blocks the pituitary gland from releasing antidiuretic hormone, which normally tells the kidneys to retain water. When the ADH is suppressed, you pee more water than you usually would, which quickly dehydrates you and your brain.

The next day, this is where you may notice the main symptoms of a hangover, including:

Extreme thirst
Dry mouth
Headaches
Dark urine
Muscle weakness

Electrolyte imbalance

As a direct follow-up on the last section, the dehydration from alcohol can also cause an electrolyte imbalance. So, when you pee more, it flushes out key electrolytes like sodium, potassium, magnesium and calcium. In chronic drinkers, blood tests will frequently show abnormally low levels of these minerals.

If you’re deficient in these minerals, you may experience issues like:

Muscle cramps
Heart palpitations
Tingling in limbs
Confusion
Dizziness
Changes in blood pressure

Blood sugar instability

When you drink alcohol, the liver blocks something called gluconeogenesis, which is the process of making new sugar for the body. This can trigger excessive insulin release when mixed with the carbohydrates that are commonly found in many alcoholic drinks, like beer. The result is a roller-coaster blood sugar ride which wreaks havoc on the body and mind.

Also, if you drink alcohol with a big meal, some may experience reactive hypoglycaemia, which is a sharp drop in blood sugar.

When this happens, you may experience symptoms like:

Shakiness

Sweating
Irritability
Anxiety
Feeling faint or dizzy
Sudden fatigue

Reduced vitamin absorption and storage

Heavy drinking starves your body’s cells of nutrients in two different ways. First, alcohol causes poor eating, especially when intoxicated or when we’re hungover. Many resort to greasy, carb-dense foods, which your body craves because of the literal wash-out of essential vitamins and minerals. If we continue this type of diet for a long time, we’re not replacing the nutrients we need to maintain a healthy body.

Second, alcohol damages the gut and liver so badly that nutrient absorption and storage become impaired. For example, a study found that alcoholics commonly become deficient in B vitamins and vitamin D. Low vitamin levels leave the body feeling depleted, which is why you may notice symptoms like:

Fatigue
Lethargy
Frequent infections from a weakened immune system
Easy bruising
Bone or joint pain from vitamin D deficiency
Poor wound healing

Nervous system imbalance

When we drink alcohol, it repeatedly turns our body’s stress responses off and on. This is partly why alcohol can feel relaxing for some, but when it wears off, there’s a rebound effect. Now the sympathetic nervous system, our fight-or-flight mechanism, is overstimulated and creating all kinds of issues. This imbalance, especially when we’re dealing with a hangover, drives symptoms like a racing heart and anxiety.

Studies back this up, too, noting a marked autonomic hyperactivity when alcohol withdrawal kicks in.

Along with anxiety and a racing heart, you may notice symptoms like:

High blood pressure
Excessive sweating
Hand tremors

Alcohol is causing problems, but I’m finding it hard to stop

If these effects keep recurring, they’re unlikely to be minor. Disrupted sleep, dehydration, blood sugar instability, nutrient depletion and nervous system strain place real pressure on the body. When alcohol use becomes regular, the body rarely gets the chance to fully recover.

If you’re noticing consistent changes, it may be worth pausing or stopping drinking to allow your system to rebalance. Even a short break can bring clearer thinking, steadier energy, improved sleep and reduced anxiety, often revealing how much strain alcohol was causing.

If this sounds familiar, reaching out for professional support can help you understand your options in a confidential and non-judgemental way.

(Click here to see works cited)

World Health Organization. (2024, June 28). Alcohol. World Health Organisation. https://www.who.int/news-room/fact-sheets/detail/alcohol
National Institute on Alcohol Abuse and Alcoholism. (2022, May). Alcohol’s effects on health. Www.niaaa.nih.gov. https://www.niaaa.nih.gov/publications/alcohol-metabolism
McCullar, K. S., Barker, D. H., McGeary, J. E., Saletin, J. M., Gredvig-Ardito, C., Swift, R. M., & Carskadon, M. A. (2024). Altered sleep architecture following consecutive nights of presleep alcohol. Sleep, 47(4). https://doi.org/10.1093/sleep/zsae003
Molina, P. E., & Simon, L. (2026). Alcohol and the endocrine system: A critical review of disruptions, potential mechanisms, and health implications. Alcohol Clinical and Experimental Research, 50(1), e70221–e70221. https://doi.org/10.1111/acer.70221
Baj, J., Flieger, W., Teresiński, G., Buszewicz, G., Sitarz, E., Forma, A., Karakuła, K., & Maciejewski, R. (2020). Magnesium, Calcium, Potassium, Sodium, Phosphorus, Selenium, Zinc, and Chromium Levels in Alcohol Use Disorder: A Review. Journal of Clinical Medicine, 9(6), 1901. https://doi.org/10.3390/jcm9061901
Oba-Yamamoto, C., Takeuchi, J., Nakamura, A., Takikawa, R., Ozaki, A., Nomoto, H., Kameda, H., Cho, K. Y., Atsumi, T., & Miyoshi, H. (2021). Combination of alcohol and glucose consumption as a risk to induce reactive hypoglycemia. Journal of Diabetes Investigation, 12(4), 651–657. https://doi.org/10.1111/jdi.13375
W. Uździcki, A., Zych, A., Świerad, B., & Wawrzynowicz-Syczewska, M. (2022). The role of vitamin and microelement supplementation in the treatment of ethanol-induced liver disease. Gastroenterology Review, 17(4), 253–256. https://doi.org/10.5114/pg.2022.121820
Finn, D. A., & Crabbe, J. C. (2025). Exploring Alcohol Withdrawal Syndrome. Alcohol Health and Research World, 21(2), 149. https://pmc.ncbi.nlm.nih.gov/articles/PMC6826827/