Do you drink more water when you have a fever? The essential guide to hydration during illness

November 25, 2025 •

4 min read

When you have a fever, your body temperature increases, which significantly speeds up your metabolism and fluid loss through sweating. For this reason, the answer to the question, “Do you drink more water when you have a fever?” is a definitive yes. Staying adequately hydrated is one of the most critical aspects of recovering from a febrile illness.

Quick Summary

During a fever, the body loses fluids more rapidly through sweating and increased metabolism. Drinking extra water and other fluids is crucial to prevent dehydration, support the immune system, and regulate body temperature for a faster recovery.

Key Points

Fever Increases Fluid Loss: Fever causes rapid fluid loss through increased sweating and respiration, making extra hydration essential to prevent dehydration.
Hydration Aids Immune Function: Drinking more water supports your immune system by helping to transport nutrients and immune cells throughout the body.
Regulates Body Temperature: Replenishing lost fluids helps your body's natural cooling mechanisms, assisting in fever management and preventing further temperature spikes.
Choose the Right Fluids: While plain water is ideal, broths, electrolyte solutions, and herbal teas can also aid hydration, while caffeinated and alcoholic beverages should be avoided.
Monitor for Dehydration: Watch for signs of dehydration like dark urine, dry mouth, or fatigue, and drink fluids proactively rather than waiting for intense thirst.
Protect Vulnerable Groups: Infants, children, and older adults are at higher risk for dehydration during a fever and require diligent monitoring and fluid intake.

The Physiological Link Between Fever and Dehydration

Fever is not an illness but a sign that your body is fighting an infection. This elevated body temperature is a natural immune response designed to make conditions less favorable for viruses and bacteria. However, this intensive internal effort has a side effect: it rapidly depletes your body's fluid reserves. There are two primary mechanisms behind this increased fluid loss:

Increased Sweating: As your body temperature rises, it initiates cooling mechanisms, with sweating being the most significant. This evaporative cooling process is highly effective but expels substantial amounts of water from your body.
Accelerated Respiration and Metabolism: A higher body temperature increases your metabolic rate and breathing speed. Every breath expels moisture from your body, and when your respiration is faster than normal, the rate of water loss through breathing also goes up.

Without an intentional increase in fluid intake, these factors can quickly lead to dehydration, which can compound the discomfort of your illness and even hinder your recovery.

The Critical Role of Hydration During a Febrile Illness

Drinking extra water when sick is more than just a home remedy; it is a clinical recommendation. Proper hydration provides several crucial benefits:

Supports Immune Function: Your immune system relies on fluid to transport immune cells, nutrients, and oxygen throughout your body. Hydration ensures your body's defenders can operate at peak efficiency.
Regulates Body Temperature: By replenishing the fluids lost through sweat, you assist your body's natural thermostat in managing its temperature. Dehydration can impair this function, potentially causing the fever to rise even higher.
Flushes Out Toxins: Water helps your kidneys and other organs flush out waste products and metabolic byproducts that accumulate as your body fights the infection.
Thins Mucus and Soothes Tissues: Staying hydrated keeps your mucous membranes moist, which can help thin mucus in your nose and throat, easing congestion and making coughing easier and more productive. It also helps lubricate your joints and tissues, which can ache and feel stiff during a fever.

How Much Water Do You Need?

During a fever, the standard 'eight glasses a day' rule no longer applies. The precise amount depends on the severity of your fever, your body weight, and whether you are experiencing other fluid-losing symptoms like vomiting or diarrhea. Some health authorities recommend aiming for an intake of 2 to 3 litres (about 67 to 101 ounces) over 24 hours while feverish. However, it is most important to listen to your body and consume fluids consistently throughout the day, even if you do not feel thirsty. Waiting for intense thirst is a sign that dehydration has already begun.

Optimal Fluid Choices

While water is the gold standard for hydration, other fluids can also be beneficial:

Oral Rehydration Solutions (ORS): These drinks contain the proper balance of water, glucose, and electrolytes to restore fluid balance quickly, especially after severe fluid loss from vomiting or diarrhea.
Broths: Chicken or vegetable broth can provide fluids, sodium, and nutrients that are easy on a sensitive stomach.
Herbal Teas: Warm teas like ginger or chamomile can be soothing and provide hydration. Avoid caffeinated teas.
Coconut Water: A natural source of electrolytes, coconut water is a healthy alternative to sugary sports drinks.

Fluids to Avoid

Caffeinated Drinks: Coffee, some teas, and energy drinks act as diuretics, increasing urination and potentially worsening dehydration.
Alcohol: Alcohol has a dehydrating effect and should be completely avoided during illness as it can also impair immune function.
Excessively Sugary Beverages: High-sugar drinks like soda can be hard to digest and do not hydrate as effectively as water or electrolyte solutions.

Hydration Comparisons During a Fever


Fluid Type	Hydration Efficacy	Electrolyte Content	Other Benefits	Things to Avoid	Ease on Stomach
Plain Water	Excellent	None	Universal; essential	N/A	Very High
Broth	Good	High (sodium)	Nutrients, soothing	High salt versions	High
Electrolyte Drink	Excellent	High	Rapid fluid replacement	High sugar content	Varies
Herbal Tea	Good	Low	Soothing, warmth	Caffeine	High
Coconut Water	Excellent	High (potassium)	Natural electrolytes	N/A	High

Monitoring for Dehydration

It's important to be aware of the signs of dehydration, as they can mimic or exacerbate fever symptoms. Key indicators include:

Extreme thirst
Dry mouth, lips, and tongue
Less frequent urination or dark-colored urine
Fatigue or dizziness
Sunken eyes
Confusion

Special Considerations for Vulnerable Groups

Infants, children, and older adults are especially vulnerable to dehydration during a fever. For infants, consult a pediatrician immediately if a fever is present, as they can dehydrate very quickly. Children should be offered small, frequent sips of fluid. Older adults may have a reduced sense of thirst, making it necessary to proactively offer them drinks.

Conclusion

In summary, the body's natural response to illness, including fever, increases the risk of dehydration through higher metabolism and sweating. To combat this, you absolutely need to drink more water when you have a fever. Doing so not only helps regulate your body temperature but also supports your immune system and overall recovery. Opt for plain water, broths, and electrolyte solutions, and be mindful of your body's signals to ensure a steady intake of fluids. Staying hydrated is a simple yet powerful way to help yourself heal faster and feel better. If your fever is severe, persistent, or accompanied by extreme dehydration, always consult a healthcare professional for guidance. For more information on dehydration, you can visit a trusted source like the Mayo Clinic.

Frequently Asked Questions

Not drinking enough water with a fever can lead to dehydration, which can cause symptoms like extreme thirst, fatigue, dizziness, and confusion. Dehydration can also make your fever worse by impairing your body's ability to regulate its temperature.

The temperature of the water you drink makes little difference to your overall body temperature, but it is best to drink what you find most comforting. Lukewarm water or herbal teas can be soothing for a sore throat, while cool water may feel more refreshing. Avoid very cold water if you have chills, as it can cause you to shiver.

During a fever, an adult should increase their fluid intake significantly. While a healthy adult typically needs around 8 glasses, a fever can increase this need to 2-3 litres (67-101 ounces) or more within 24 hours, depending on the severity of the fever and other symptoms.

While dehydration does not directly cause an infection-related fever, it can increase your body's temperature by making it harder to cool down through sweating. In severe cases, dehydration can lead to heat exhaustion or heat stroke, which are associated with high body temperatures.

To encourage a child to drink, offer small, frequent sips of water, oral rehydration solutions (like Pedialyte), ice pops, or clear broths. Make sure these are age-appropriate and avoid caffeine. If a child refuses to drink or shows signs of severe dehydration, seek medical advice.

For mild fevers, plain water is often sufficient. However, if you are experiencing significant fluid loss through sweating, vomiting, or diarrhea, electrolyte-rich drinks are recommended to replenish essential minerals like sodium and potassium.

Drinking more water doesn't directly lower your temperature but supports your body's ability to regulate it and fight the underlying infection. By preventing dehydration and aiding bodily functions, it creates a better environment for your body to recover efficiently.