Energy drinks are generally a poor choice when you’re sick. Their combination of high caffeine, large doses of sugar, and stimulant additives works against several things your body needs most during illness: hydration, sleep, a calm digestive tract, and a functioning immune response. While one ingredient, taurine, does have legitimate anti-inflammatory properties, and caffeine can temporarily ease the foggy feeling of a cold, the overall package creates more problems than it solves for someone fighting off an infection.
The Hydration Problem
When you’re sick, especially with a fever, vomiting, or diarrhea, staying hydrated is one of the most important things you can do. Energy drinks might seem like they’d help since they are, after all, liquids. But the caffeine in most energy drinks works against you. A meta-analysis of research on caffeine and urine output found that a median dose of about 300 mg of caffeine, roughly the amount in two standard energy drinks or one large can, increased urine volume by about 16% compared to caffeine-free conditions.1PubMed Central. Caffeine and diuresis during rest and exercise: A meta-analysis That may not sound dramatic, but when you’re already losing fluid through sweat, mucus, or GI symptoms, an extra push toward urination is the last thing you need.
During exercise in the heat, caffeine also increased sweat losses of sodium, chloride, and potassium by roughly 14% and boosted urine flow by 28%.2PubMed. Caffeine during exercise in the heat: thermoregulation and fluid-electrolyte balance A feverish body faces a similar thermoregulatory challenge. Your core temperature is elevated, you’re sweating, and you need to hold onto electrolytes. A drink that accelerates the loss of sodium and potassium is counterproductive.
The sugar content creates its own hydration issue. Many energy drinks contain 50 to 80 grams of sugar per can. When a large amount of sugar arrives in the gut faster than the intestine can absorb it, the excess draws water into the intestinal lumen through osmosis. Research on sugar-sweetened beverages has shown that the high osmotic load from poorly absorbed sugars like fructose can exceed the absorptive capacity of the gut, compounding diarrhea rather than resolving it.3The International Journal of Medical Science and Health Research. The Association Between Sugar-Sweetened Beverage Consumption and Toddler’s Diarrhea: A Systematic Review While that particular research focused on young children, the underlying mechanism, osmotic pull from unabsorbed sugars, applies to anyone with an already irritated gut.
Sugar and Your Immune Response
Beyond hydration, the sugar load in energy drinks may temporarily blunt one of your immune system’s key defenses. A classic study in the American Journal of Clinical Nutrition found that consuming 100 grams of simple carbohydrates from glucose, fructose, sucrose, honey, or orange juice all significantly reduced the ability of neutrophils, a type of white blood cell, to engulf bacteria. The effect kicked in fast, peaking one to two hours after consumption, and phagocytic function remained suppressed for at least five hours.4The American Journal of Clinical Nutrition. Role of sugars in human neutrophilic phagocytosis
A single energy drink doesn’t deliver 100 grams of sugar, but it’s easy to get into that range if you’re sipping multiple cans throughout the day, which some people do when they want to “push through” an illness. The study found that the number of white blood cells didn’t change; it was their effectiveness that dropped. Your body had the same number of soldiers, but they were fighting at reduced capacity. When you’re already battling an infection, giving your immune cells any disadvantage, even a temporary one, seems like poor strategy.
Caffeine, Sleep, and Recovery
Sleep is one of the most powerful tools your body has for fighting infection. Research has established that sleep promotes host defense against infections, and that sleep deprivation alters both the innate and adaptive arms of the immune system, pushing the body toward a chronic inflammatory state and increased vulnerability to infectious diseases.5PubMed Central. Role of sleep deprivation in immune-related disease risk and outcomes The last thing you want when your body is marshaling its immune resources is to chemically block the very process that coordinates them.
Most energy drinks contain anywhere from 80 to 300 mg of caffeine. Caffeine’s half-life in the body is roughly five to six hours, meaning that even a single can consumed at noon could still be circulating in meaningful amounts at bedtime. Sick people often feel drowsy because the immune system’s signaling molecules actively promote sleep as part of the healing process. Fighting that drowsiness with stimulants doesn’t make you better faster; it interferes with the repair cycle your body is trying to run.
What Energy Drinks Do to Your Stomach When You’re Already Unwell
Even healthy people sometimes get a sour stomach from energy drinks. When you’re sick, the effect can be substantially worse. A study of gastrointestinal symptoms found that energy drink consumption was linked to more than double the odds of burning stomach pain, more than four times the odds of bloating, and nearly six times the odds of heartburn compared to non-consumers.6PubMed Central. Self-Reported Gastrointestinal Symptoms Associated with NSAIDs and Caffeine Consumption in a Jordanian Subpopulation Appetite changes were also significantly more likely among energy drink users.
If you’re dealing with a stomach bug, a respiratory illness that’s making you nauseated, or you’ve been taking over-the-counter medications like ibuprofen that already irritate the stomach lining, adding an acidic, caffeinated, sugar-laden drink on top is asking for trouble. The carbonation in most energy drinks adds another layer: it distends the stomach and can trigger reflux, especially if you’re lying down. Many people with colds or flu are spending more time reclined, which makes reflux worse.
Cardiovascular Stress on a Sick Body
Your cardiovascular system is already working harder when you’re sick. A fever raises heart rate by roughly 10 beats per minute for every degree of temperature increase. Dehydration reduces blood volume, which further elevates heart rate as the heart compensates. Energy drinks layer additional cardiovascular stress on top of this baseline strain.
A systematic review of cardiovascular effects found that over 60% of the studies reviewed showed energy drinks significantly increased heart rate, and a similar proportion found increases in both systolic and diastolic blood pressure. More than 60% of studies also observed prolongation of the QTc interval, an electrocardiogram marker associated with arrhythmia risk.7PubMed Central. The Effects of Energy Drinks on the Cardiovascular System: A Systematic Review For a healthy twenty-something sitting at a desk, these effects are usually temporary and manageable. For someone whose heart is already beating fast due to fever, whose electrolytes may be off due to vomiting or diarrhea, or who has an underlying cardiac condition they may not even know about, the combination becomes riskier.
This is especially worth thinking about if you’re taking any decongestants containing pseudoephedrine or phenylephrine, both of which are stimulants in their own right. Stacking those with caffeine and the other stimulant compounds in energy drinks can amplify the cardiovascular load in ways that are difficult to predict. Anyone taking prescription medications for a heart condition, diabetes, seizure disorders, or mood disorders should be particularly cautious.8PubMed Central. Health effects of energy drinks on children, adolescents, and young adults
The One Thing Caffeine Actually Helps With
It isn’t all bad news. One legitimate benefit of caffeine when you have a cold is that it temporarily reverses the mental fog and sluggishness that make you feel miserable. A study on caffeine and the common cold found that caffeine restored alertness and cognitive performance in people with colds to the same level as healthy subjects. Interestingly, even decaffeinated coffee produced some improvement, suggesting that the sensory experience of drinking a warm, aromatic beverage may itself offer a mild boost.9PubMed. Caffeine and the common cold
This doesn’t mean caffeine helps you heal. It means it can mask the malaise, which is useful if you absolutely need to function for a few hours but potentially harmful if it encourages you to skip the rest your body is demanding. The alertness effect also doesn’t require an energy drink. A cup of tea or coffee delivers the same cognitive lift without the sugar bomb, the taurine, the guarana, or the other stimulant additives.
Taurine Has Real Anti-Inflammatory Properties, but Context Matters
Taurine is one of the most common ingredients in energy drinks, and unlike many energy drink additives, it has a genuinely interesting research profile for inflammation. Taurine has been shown to have antioxidant and anti-inflammatory effects, and compounds formed when taurine reacts with immune-cell byproducts have antimicrobial properties as well.10PubMed Central. Taurine and inflammatory diseases
In laboratory and animal studies, taurine supplementation reduced inflammatory markers like TNF-alpha and IL-1beta in immune cells challenged with bacterial toxins. In mice with sepsis, taurine protected against organ damage in the lungs, liver, and kidneys by reducing excessive inflammation and neutrophil infiltration.11PubMed. Mechanism of taurine reducing inflammation and organ injury in sepsis mice Those are promising findings, but it’s worth noting that sepsis is an extreme condition, and what works in a mouse model doesn’t automatically translate to a person with a head cold.
The taurine in a typical energy drink comes packaged with all the other ingredients discussed above. Getting taurine’s potential anti-inflammatory benefits while simultaneously hammering your immune system with sugar, disrupting your sleep with caffeine, and irritating your stomach with acid and carbonation is like putting premium fuel in a car while slashing the tires. If taurine supplementation interests you during illness, standalone taurine capsules exist and avoid the collateral damage of the full energy drink package.
Better Alternatives When You’re Sick
What should you drink instead? The answer depends on how sick you are and what symptoms you have.
For a straightforward cold or mild flu with no significant vomiting or diarrhea, water and warm liquids like tea or broth are generally all you need. Warm liquids can help loosen congestion and soothe a sore throat, and as the caffeine-and-cold study showed, even the sensory stimulation of a warm drink can ease malaise.
If you’re losing fluids through vomiting or diarrhea, electrolyte replacement becomes more important. Oral rehydration solutions, which contain a specific balance of sodium, potassium, and glucose designed to maximize absorption, are the gold standard. A randomized trial comparing a sports drink, a standard oral rehydration solution, and a pediatric electrolyte solution in adults with viral gastroenteritis found that the sports drink group had more cases of low potassium and low sodium than the groups using purpose-built rehydration products.12PubMed. Oral rehydration for viral gastroenteritis in adults: a randomized, controlled trial of 3 solutions If a sports drink falls short of proper rehydration, an energy drink, with even more sugar and added stimulants, performs worse still.
Research on rehydration after significant fluid loss has also found that drinks with amino acids produced better fluid retention, about 75% versus 57%, compared to standard sports beverages.13PubMed. Efficacy of Glucose or Amino Acid-Based Commercial Beverages in Meeting Oral Rehydration Therapy Goals After Acute Hypertonic and Isotonic Dehydration The key takeaway is that not all liquids rehydrate equally, and the formulation matters. Energy drinks were never designed for rehydration; they were designed to deliver a caffeine and sugar rush.
Children and Teenagers Should Be Especially Careful
The risks of energy drinks during illness are amplified for younger people. A review in Pediatrics noted that energy drinks frequently contain high and unregulated amounts of caffeine and have been reported in association with serious adverse effects in children, adolescents, and young adults, particularly those with seizure disorders, diabetes, cardiac abnormalities, or mood and behavioral disorders. Of the more than 5,400 caffeine overdoses reported to US poison centers in 2007, nearly half occurred in people younger than 19.8PubMed Central. Health effects of energy drinks on children, adolescents, and young adults
Children are more sensitive to caffeine per unit of body weight, and their cardiovascular and neurological systems are still developing. A sick teenager who grabs an energy drink because they “need the energy” to get through a school day is stacking pharmaceutical-level doses of caffeine on top of whatever cold medication their parents gave them that morning. Reports of caffeine toxicity from energy drinks have been increasing, and medical researchers have called for better labeling and restricted sales to minors.14Medical Journal of Australia. Energy drinks: health risks and toxicity
When the Answer Might Be Different
There are a few narrow scenarios where a small energy drink might not be the worst choice. If you have a mild cold with no fever, no GI symptoms, and no meaningful dehydration, and you need to be functional for a few hours, a single small can consumed early in the day is unlikely to cause harm in an otherwise healthy adult. The caffeine will temporarily ease your brain fog, and if you follow it with plenty of water and get to bed at a reasonable hour, the net impact on recovery is probably minimal.
But that’s a lot of conditions to meet, and even then, a cup of coffee or tea achieves the same cognitive benefit with fewer downsides. The honest assessment is that energy drinks sit in a category of beverages that were engineered for a very specific use case, sustained alertness in healthy people, and illness is almost the opposite of that use case. Your body is telling you to slow down, hydrate, and sleep. An energy drink tells your body to speed up, shed fluid, and stay awake. Those signals don’t combine well.
If you’re someone who relies on energy drinks daily and you’re worried about caffeine withdrawal headaches during an illness, a more measured approach is to get your baseline caffeine from a small coffee or tea, which gives you just the caffeine without the sugar, additives, and carbonation. Caffeine withdrawal headaches typically peak within a day or two and resolve on their own, so even going cold turkey is an option if you’re planning to spend a few days in bed anyway.