John KIRAGU
- Mar 17
- 4 min read

Understanding the effects of caffeine and alcohol: how to consume them in moderation

"Caffeine masks the effects of alcohol and makes you feel more capable or alert." - John K.

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Caffeine is a central nervous system stimulant that makes your body feel alert and energetic, while alcohol is a depressant that makes your body feel less alert and sleepy. When you mix alcohol and caffeine, caffeine increases your energy by blocking the adenosine receptors in your brain, ceasing the sleeping signal and bucking you up, while alcohol increases the accumulation of adenosine in your system, resulting in poor judgment, slow reaction times, and reduced motor skills and balance.

Alcohol and caffeine are diuretics, which result in dehydration accompanied by symptoms such as passing dark urine, feeling lightheaded or dizzy, feeling thirsty, and having a dry mouth. As a result, caffeine leads to excess alcohol consumption, which can result in a depressed adrenal gland, low cortisol level, impaired immune system, increased inflammation, and disrupted sleep. It also causes a rise in blood sugar, which triggers the overproduction of insulin by the pancreas.

Caffeine

Caffeine is a pharmacologically active substance found in beverages such as soft drinks, coffee, and tea that increases your alertness and boosts your mental and physical performance. It helps stimulate your heart, muscles, and nervous system. Intake of caffeine greater than 400 mg (4 cups) can result in various side effects in your body, including:

Insomnia

Caffeine is a stimulant that acts as an adenosine receptor antagonist, which also affects the glial cells and the neurons of all the brain areas. It also inhibits phosphodiesterase, interferes with GABA-A receptors, and increases calcium production in the intercellular store. Caffeine blocks the adenosine receptors affecting your brain function, such as cognition, memory, and learning, and sleep to keep you active and awake, therefore reducing the quality and quantity of your sleep.

Increased heart rate

Caffeine has various effects on your central nervous system and can lead to an altered heartbeat rhythm known as atrial fibrillation. Caffeine stimulates the receptors in cells within your heart, increasing the heart rate. The intake of caffeine increases the level of epinephrine, which causes the rise in blood pressure and hence the increased heart rate. Ultimately, caffeine results in palpitations in people who are prone to abnormal heart rhythms. Caffeine also promotes the production of stress hormones such as cortisol, norepinephrine, and adrenaline, thus causing your heart rate to increase.

Trembling hands
rise in temperature
Frequent urination
Anxiety

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Caffeine has the blocking effect of adenosine, a chemical that makes you feel tired and sleepy and triggers the release of epinephrine - a hormone linked with increased energy. When the adrenaline is activated, it triggers a host of physical and physiological reactions such as muscle tension and increased blood pressure, which ramp up your sympathetic nervous system. Ultimately, caffeine's effects on the central nervous system can trigger the "flight or fight" response, making you feel anxious and irritable. According to Harvard Medical School, consumption of caffeine can exacerbate the symptoms of anxiety, such as restlessness, gastrointestinal problems, nausea, and dizziness.

Alcohol

Alcohol is a depressant that alters the brain’s communication pathway and can also affect the way your brain functions and looks, thus affecting your moods, balance, and reflexes. Alcohol intake can also cause dilated cardiomyopathy - a condition that lessens the heart's ability to pump blood due to the weakening and enlargement of the main chamber. Alcohol can result in liver injuries when consumed in excess.

Alcohol is metabolized by the body into acetaldehyde and acetone, both of which are harmful to the hepatocyte. As a result, the damaged hepatocytes release endogenous danger molecules that conscript adaptive immune cells that prolong liver injuries. The common symptoms of liver disease include swelling in the legs, dark urine, chronic fatigue, vomiting and nausea, yellow eyes and skin, and discolored stools.

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The 2020–2025 dietary guidelines for Americans recommend that the moderate intake of alcohol be 1 drink or less for women in a day and 2 drinks or less in a day for men. Excess alcohol intake can result in various effects on your body including:

Changes in vision, perception, and hearing

Alcohol, as a depressant, can weaken the eye-muscle coordination, leading to blurry vision. It can also result in a slower reaction time due to a delayed pace of communication between neurotransmitters in your brain that weakens eye-muscle coordination. Effects of alcohol intake alter how you process information, perceive reality, and make decisions as it affects your central nervous system.

Memory problems

Excess alcohol intake results in a condition known as alcohol dementia, that result in impaired judgment, the inability to perform tasks, difficulties speaking, and memory loss. Alcohol-related dementia is linked with two conditions: Korsakoff’s syndrome and Wernicke’s disorder. Wernicke’s encephalopathy results in a loss of muscle coordination and brain damage caused by a lack of thiamine. Korsakoff’s psychosis results in confabulation and memory loss.

Serious accidental injuries
Alcohol withdrawal syndrome
Suicide
Heart muscle damage due to alcoholic cardiomyopathy causes heart failure.

How to moderate the intake of alcohol and caffeine

Combining alcohol and caffeine may potentially result in effects such as taking more alcohol, alcohol poisoning, addiction, and worsening alcohol-related consequences. Knowing the effects of mixing caffeine and alcohol, it is important to avoid doing so altogether. If you choose to combine alcohol and caffeine, here are some safe tips that help you consume it moderately.

Space out your drinks and take caution with the amount of alcohol that you consume.
Take caffeinated alcoholic beverages occasionally.
Be mindful of the quantity of caffeine that you consume since different caffeinated beverages contain different amounts of caffeine.
Avoid any drink that you did not mix, and consume mixed drinks with those whom you trust.

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When alcohol is mixed with caffeine, the caffeine masks the depressant effect of alcohol, making drinkers feel more alert than usual. Excess alcohol consumption is linked with various social problems, such as interpersonal violence, alcohol-impaired driving, and the risks of unintended pregnancy. Caffeine and alcohol also contribute to various health issues such as chronic diseases, loss of memory, anxiety and insomnia, various types of cancer, high blood pressure, and an increased risk of heart problems.

Caffeine and alcohol should not be mixed, as they can result in a irretrievable damage to your body. Alcohol and caffeine can potentially mask the blood alcohol level to the point of causing death; therefore, it is best to understand your body and act responsibly.