Drinking warm water supports digestion, eases nasal congestion, and may gently boost your metabolism, though the effects are more modest than many wellness sites suggest. Most of the benefits come from staying hydrated in general, but water temperature does make a measurable difference in a few specific areas.
How Warm Water Affects Digestion
Your stomach contracts rhythmically to break down food and move it along, and water temperature directly influences how active those contractions are. In a study of healthy young men, drinking 500 ml (about two cups) of water at 60°C (140°F) kept gastric contractions at a higher frequency than the same amount of ice-cold water at 2°C. Cold water actually suppressed stomach contractions and reduced appetite afterward. Water close to body temperature (37°C, or about 98°F) performed similarly to warm water.
What this means in practice: warm or room-temperature water keeps your digestive system moving at its normal pace, while very cold water temporarily slows it down. If you feel bloated or sluggish after meals, switching from ice water to warm water is a simple change worth trying.
Clearing Congestion and Nasal Passages
One of the clearest, most immediate effects of warm water is on your sinuses. Sipping hot water increased nasal mucus velocity from 6.2 to 8.4 millimeters per minute in a controlled study, a statistically significant improvement over cold water. The effect comes partly from inhaling the steam as you sip. Cold water, by contrast, actually slowed mucus movement from 7.3 down to 4.5 mm per minute.
The congestion relief is temporary. Mucus velocity returned to baseline within 30 minutes. But if you’re dealing with a stuffy nose from a cold or allergies, sipping warm water throughout the day offers real, repeatable relief. Drinking through a straw, which bypasses the steam, produced a weaker effect, so sipping from an open cup matters.
A Small Metabolic Boost
Drinking water of any temperature raises your metabolic rate as your body processes the fluid. One study found that drinking 500 ml of water increased metabolism by about 30%, burning roughly 24 extra calories per session. About 40% of that thermogenic effect came specifically from your body warming the water from room temperature (22°C) up to body temperature (37°C).
This creates an interesting twist: cold water actually produces a slightly larger metabolic bump than warm water, because your body has to spend more energy heating it. But the total difference is tiny. Drinking two liters of water per day adds up to roughly 96 extra calories burned, regardless of temperature. That’s helpful as one small habit among many, but it won’t drive meaningful weight loss on its own.
Muscle Relaxation and Pain Relief
Warm water can help relax both smooth muscle (the type lining your digestive tract and uterus) and skeletal muscle. This is why a warm drink often feels soothing when you have stomach cramps or menstrual pain. The mechanism is similar to applying a heating pad: warmth increases blood flow to the area and reduces muscle tension.
The effect is gentle and works best for mild discomfort. If you experience regular menstrual cramps or abdominal tightness, warm water is a low-risk option that complements other approaches.
Circulation and Blood Flow
Most of the research on warm water and circulation involves warm water immersion (bathing) rather than drinking, so the effects of drinking warm water on blood flow are less dramatic. That said, external warm water exposure at around 40°C increased blood flow in the femoral artery by nearly 46% and decreased leg vascular resistance by 29%. Heart rate and diastolic blood pressure dropped after just five minutes, and arterial stiffness in the aorta decreased by 7.5%.
Drinking warm water raises your core temperature far less than a warm bath does, so you shouldn’t expect the same magnitude of vascular changes from a cup of warm water. Still, the general principle holds: warmth promotes vasodilation, which means your blood vessels relax and widen slightly, improving circulation.
What Temperature Is Best
For everyday drinking, anywhere from body temperature (37°C/98°F) up to about 60°C (140°F) captures the digestive and congestion benefits without any safety concerns. The sweet spot for most people is water that feels comfortably warm but not hot enough to sting your lips.
The important cutoff to know: the International Agency for Research on Cancer classifies beverages above 65°C (149°F) as probably carcinogenic, specifically linked to squamous cell carcinoma of the esophagus. That temperature is hotter than most people would comfortably drink, but if you regularly drink scalding tea or water, letting it cool for a few minutes is a worthwhile habit. A good rule of thumb is that if you have to blow on it before each sip, it’s likely too hot.
Warm Water vs. Cold Water
Neither temperature is universally better. Each has specific advantages depending on your goal:
- For digestion: Warm or room-temperature water keeps stomach contractions at their normal rate. Cold water temporarily slows them.
- For congestion: Warm water wins clearly, improving mucus flow while cold water worsens it.
- For calorie burn: Cold water has a slight edge, since your body works harder to warm it. The difference amounts to a few calories per glass.
- For exercise: Cold water is generally preferred because it helps lower core body temperature during and after exertion.
- For comfort and relaxation: Warm water helps relax muscles and feels soothing, especially during illness or cramps.
As a Cleveland Clinic gastroenterologist has noted, the science on water temperature and health is thinner than you might expect, and much of the choice comes down to personal preference. The most important thing is that you drink enough water, period. If warm water feels better and encourages you to drink more, that alone makes it the right choice for you.