Does Milk Count as Hydration When Sick? The Definitive Guide

October 24, 2025 •

4 min read

While water is often considered the gold standard for hydration, a 2016 study published in the American Journal of Clinical Nutrition found that both whole milk and skim milk provide superior hydration to plain water after exercise. But does milk count as hydration when sick and is it the best choice for fluid replacement?

Quick Summary

Milk provides hydration due to its water, electrolyte, and nutrient content. However, its suitability when sick depends on the type of illness, as its fat content can slow absorption and create a perception of thickened mucus, potentially making some symptoms feel worse. While it can offer soothing calories and protein, other options may be better for rapid rehydration.

Key Points

Milk Is a Hydrating Liquid: Milk contains a high percentage of water, along with electrolytes, protein, and carbs that promote sustained fluid retention in the body.
Superior to Water for Retention: Studies show that milk can be more effective than water at keeping the body hydrated for longer periods due to its nutrient composition.
The Mucus Myth is False: Research has debunked the idea that milk increases or thickens mucus production. The creamy texture simply creates a temporary perception of thickness in the mouth.
Consider Symptoms When Choosing: For digestive issues like vomiting, lighter fluids like water or oral rehydration solutions may be easier to tolerate. Milk's fat content can feel heavy.
Milk Offers Nutrients for Recovery: When tolerated, milk provides valuable calories and protein that can be beneficial for those with a suppressed appetite while sick.
Mix and Match Fluids: The best strategy often involves a variety of fluids, including water, broth, and tea, and incorporating milk when symptoms allow and appetite is low.

The Science of Milk and Hydration

At its core, milk is a liquid, with whole milk being around 88% water and skim milk being about 90% water. This high water content means it directly contributes to your daily fluid intake. Beyond plain water, milk offers several components that enhance its hydrating effects, particularly its natural blend of electrolytes, carbohydrates, and protein.

Electrolytes: These are essential minerals like sodium, potassium, and calcium that help regulate the body's fluid balance. Milk naturally contains these electrolytes, which are lost through sweating, vomiting, or diarrhea during an illness. Rehydrating with an electrolyte-containing beverage can be more effective than plain water in replenishing these lost minerals.
Carbohydrates and Protein: The presence of these macronutrients in milk slows down the rate at which fluids leave the stomach. This leads to a more sustained absorption and retention of fluids in the body over a longer period, which can be particularly beneficial for replenishing fluids effectively. For instance, a 2016 study found that milk helped maintain fluid balance better than water or a sports drink by reducing urine output.

Milk and the Mucus Myth

A long-standing myth suggests that drinking milk increases or thickens mucus, making congestion worse when you are sick. This belief has been debunked by scientific research. Studies have shown no significant link between milk consumption and increased mucus production, nasal secretions, or coughing. The perceived effect is likely due to the texture of milk. The emulsion of fat in milk mixes with saliva, creating a temporary sensation of a thicker coating in the mouth and throat. This can feel uncomfortable for some, but it does not physiologically worsen your respiratory symptoms.

Potential Drawbacks of Milk When You're Sick

While milk has hydrating benefits, it is not always the best choice, depending on your symptoms.

Slow Absorption: The fat and protein in milk, while promoting sustained hydration, can also make it a heavier beverage to digest. If you are experiencing nausea, vomiting, or a stomach bug, a heavy drink could worsen digestive discomfort. Lighter fluids may be easier to tolerate.
Lactose Intolerance: If you have lactose intolerance, consuming dairy while sick could lead to additional digestive issues like bloating, cramps, or diarrhea, which would further exacerbate dehydration. In this case, choosing a lactose-free alternative or a different hydrating beverage is a better option.
Calorie Content: For general illness where appetite is low, the calories and nutrients in milk can be a benefit. However, if your main goal is simply to rapidly replace fluids, a lower-calorie option like water or an oral rehydration solution might be more appropriate to avoid feeling full too quickly.

Comparison of Hydration Drinks When Sick


Beverage	Key Hydration Benefits	Best for...	Potential Drawbacks
Milk	Water, electrolytes (calcium, sodium, potassium), protein, carbs for sustained fluid retention.	Providing calories and sustained hydration for general illness, especially after exercise.	Heavier to digest; may worsen nausea; not ideal for rapid rehydration or those with lactose intolerance.
Water	No calories, purest form of fluid replacement.	Basic, continuous hydration. The go-to for most situations.	Lacks electrolytes and calories, which might be needed in severe dehydration cases.
Oral Rehydration Solutions (ORS)	Optimized balance of electrolytes (sodium, potassium) and glucose for rapid absorption.	Replenishing fluids lost from severe vomiting or diarrhea.	Often higher in sugar; specific taste may be off-putting to some.
Broth/Soup	Electrolytes (sodium), fluids, and warmth for soothing a sore throat.	Colds, flu, and soothing a sore throat. Also provides some calories and nutrients.	Can be high in sodium. May not provide enough fluid if consumed alone.
Herbal Tea	Water, antioxidants (depending on type), and warmth.	Soothing a sore throat and congestion. Caffeine-free options are best.	Not a significant source of electrolytes or calories.

Practical Recommendations for Staying Hydrated When Sick

Your best approach to hydration while sick is often a combination of fluids, tailored to your specific symptoms.

Listen to Your Body: If you feel thirsty, drink. If milk feels heavy on your stomach, switch to something lighter. Conversely, if you have a poor appetite and can tolerate milk, it can be a good way to get calories and protein along with your fluids.
Start with Bland Fluids: For stomach bugs involving vomiting or diarrhea, start with clear, bland fluids like water or oral rehydration solutions to prevent upsetting your stomach further. Sips of broth or ice chips can also be helpful if you are struggling to keep fluids down.
Use Milk Strategically: Consider using milk as a hydrating option for a lingering cold or flu once severe digestive symptoms have passed. A smoothie with yogurt, fruit, and milk can provide immune-boosting nutrients like probiotics, vitamin D, and zinc.
Monitor Your Urine: A simple, reliable way to check your hydration status is to monitor your urine color. Pale yellow urine indicates good hydration, while dark yellow or amber urine suggests you need to increase your fluid intake.
Avoid Dehydrating Beverages: Steer clear of alcohol and limit caffeine intake, as both can have diuretic effects and work against your rehydration efforts.

Conclusion: The Verdict on Milk and Hydration When Sick

Yes, milk technically counts as hydration when sick due to its high water content and beneficial blend of electrolytes, carbohydrates, and protein. In some instances, it may even be more effective than plain water for long-term fluid retention. However, the key is knowing when it is the right choice. For a stomach bug with nausea or vomiting, lighter, clearer fluids are typically better tolerated and absorbed more quickly. For a cold or flu without severe digestive issues, milk can provide soothing calories and nutrients alongside its hydrating properties. Ultimately, your choice should be guided by your specific symptoms and what feels best for your body, ensuring you maintain a consistent intake of fluids to aid in recovery.

Authoritative link example: The American Journal of Clinical Nutrition

Frequently Asked Questions

No, milk is not bad for a cold or the flu. The belief that it increases mucus is a myth. While it can create a temporary feeling of a thicker coating in the throat, it does not worsen congestion or mucus production.

The best drink depends on your symptoms. For rapid rehydration from severe fluid loss (vomiting, diarrhea), oral rehydration solutions are most effective. For a general illness, water is great, and options like broth or milk (if tolerated) can provide extra nutrients.

It is generally not recommended to drink milk with a stomach bug. The fat and protein can be heavy and may worsen symptoms like nausea and vomiting. It is better to start with clear, bland fluids and progress to milk as you feel better.

Skim milk is slightly more hydrating than whole milk because its lower fat content means it has a higher water percentage. Both are effective hydrators due to their electrolytes and other nutrients.

While milk is hydrating, water should remain your primary fluid source for daily hydration needs. Milk is a good supplement, especially if you need extra calories or nutrients when your appetite is low.

Symptoms of dehydration include feeling thirsty, having dark-colored urine, peeing less often, feeling dizzy or lightheaded, and having a dry mouth or lips. Pay attention to these signs and increase your fluid intake.

The temperature of the milk is a matter of personal preference. Some people find warm liquids soothing for a sore throat, while others prefer chilled drinks. Both provide hydration and potentially soothing effects.