What happens to the body if you don't drink enough water in winters?

Feeling tired, dry or foggy this winter? Doctors reveal how inadequate hydration in cold weather disrupts circulation, digestion and immunity

Winter often tricks the body into thinking it needs less water. With cooler temperatures, reduced sweating and fewer reminders to sip fluids, dehydration quietly creeps in, often without the classic feeling of thirst. Doctors warn that ignoring hydration in colder months can affect everything from digestion and kidneys to heart health and immunity.

 

According to Dr Tushar Tayal, associate director for internal medicine at CK Birla Hospital, Gurugram, winter dehydration is common, under-recognised and frequently mistaken for seasonal fatigue or ageing. Winters may dull thirst, but the body’s need for water does not change.

 

Why thirst signals drop in winter

 

In colder weather, the body undergoes several physiological changes that reduce the urge to drink water. Sweating decreases, creating the perception that fluid loss is minimal, even though water continues to leave the body through breathing, urine, and the skin.

 

 

Cold weather also triggers cold diuresis. Blood vessels constrict, pushing more blood towards the body’s core and prompting the kidneys to excrete more urine. “This causes increased water loss without the person consciously realising it,” Dr Tayal explains.

 

Less sunlight, reduced physical activity and prolonged time indoors further lower voluntary water intake.

Heating systems accelerate moisture loss, while the hypothalamus, the brain’s thirst regulator, becomes less responsive in cold climates, allowing dehydration to set in without obvious thirst.

 

Early warning signs people often miss

 

Winter dehydration rarely announces itself clearly. Instead, it masquerades as common cold-weather complaints. Symptoms such as weakness, headaches, dry lips, dizziness, reduced urine output or dark-coloured urine are often blamed on lack of sleep or seasonal sluggishness. Other overlooked signs include: 

• Muscle stiffness and body aches
• Constipation and bloating
• Difficulty concentrating
• Excessively dry skin or dandruff

 

“People often treat dry skin or drowsiness in isolation, without recognising dehydration as the root cause,” says Dr Tayal.

 

What dehydration does to digestion and kidneys

 

Water plays a central role in digestion and waste elimination. When intake drops, digestive processes slow down. Constipation, acidity and bloating become more common during winter dehydration.

 

Kidneys are especially vulnerable. “Adequate water is essential for the kidneys to cleanse the body effectively,” Dr Tayal notes. Dehydration forces them to work harder, increasing the risk of kidney stones and urinary tract infections.

Reduced fluid intake also limits toxin removal, allowing waste products to linger and contribute to fatigue and metabolic disturbances.

 

Effects on blood pressure and heart health

 

Low hydration reduces blood volume, forcing the heart to pump harder to maintain circulation. This can lead to fluctuations in blood pressure, dizziness and, in some cases, orthostatic hypotension, a sudden drop in blood pressure when standing up, particularly common in older adults.

 

Dehydration also thickens the blood, raising the risk of clot formation. Combined with winter-related blood vessel constriction, this places added strain on the heart, especially in people with existing cardiovascular conditions.

 

Impact on skin, immunity and infections

 

Dry, cracked skin is one of the most visible signs of winter dehydration. Lack of fluids reduces skin elasticity and accelerates signs of ageing.

 

Hydration is equally important for immune defence. Fluids help transport immune cells and maintain the protective lining of the nose and throat. “When these linings dry out, the body becomes more vulnerable to respiratory infections like colds and flu,” explains Dr Tayal. Poor hydration also slows recovery by impairing waste removal from the body.

 

How much water do you really need in winter?

 

Experts recommend maintaining the same fluid intake year-round - around 2.5 to 3 litres daily for most adults. Warm fluids such as soups, broths and herbal teas contribute to hydration and are often easier to consume in winter.

 

However, caffeinated drinks like tea and coffee should be limited, as they have mild diuretic effects. “Water remains the best source of hydration,” Dr Tayal emphasises. Adding warm water, seasonal fruits and water-rich vegetables can make staying hydrated more appealing during colder months.