For 14-year-old Maya Kulkarni, winter isn’t about hot cocoa and holiday. It’s about a never-ending box of tissues. Every year as December settles in, her morning starts with incessant sneezes, about 10-15, followed by a persistent runny nose and itchy, watery eyes. What her parents initially thought was just a “lingering cold” is actually allergic rhinitis, a condition where a weak immune system reacts to indoor triggers like dust mites and mold that flourish in rooms shut tightly to keep cold at bay.
What Winter Does to Your Body
Maya finds herself constantly fatigued and ends up missing school often, not because of a new virus, but because her body wastes its defence fighting harmless allergens rather than tackling seasonal threats. Maya’s story is a classic example of why building winter immunity isn’t just about avoiding germs, it’s about training the immune system to be smart, resilient, and balanced.
Dr. Siri M. Kamath, Consultant, Internal Medicine, Gleneagles BGS Hospital, Bengaluru explains, “Dry air is one of the biggest culprits. The moisture in our upper airway serves as a protective layer, trapping and flushing out viruses. During winter, this protective lining tends to dry out faster, particularly in polluted cities or when people stay for long periods in heated or air-conditioned rooms. Once the mucosal layer is dry and irritated, viruses find it easier to attach. The immune cells that patrol these surfaces also don’t function as well without adequate moisture. This is why people complain of a raw throat, nasal irritation, or coughing more during this season, even before an infection sets in.”
As per a research, the reduced exposure to sunlight is the main culprit. Sunlight is the natural source of Vitamin D, which in turn supports and maintains our immune system health. Vitamin D has also been linked to a lower risk of respiratory infections.
A paper published on Springer Medicine says “Vitamin D has been shown to influence the function of cells intrinsic to innate and adaptive immunity.” The National Cancer Institute defines adaptive immunity as “a type of immunity that develops when a person’s immune system responds to a foreign substance or microorganism, such as after an infection or vaccination.”
Vitamin D is essential for T-reg cells – white blood cells that regulate our immune system response but low exposure to sunlight affects Vitamin D and in turn T-reg cells.
Why we need stronger immunity
Dr Ranjith J, Senior Consultant, Internal Medicine, Narayana Healthcity, states, “Building a truly resilient immune system (achieving immunocompetence) is not a seasonal intervention but a consistent, year-round commitment to optimizing physiological functions that support immune cell development and activity.”
Young children and older adults are most likely to suffer from respiratory problems during winters. “Kids’ airways are naturally narrow, so even minor swelling can make it harder to breathe. In older adults the immune system responds more slowly than before, and long-term health issues or some medications can make it slower still. For people living with asthma, COPD, diabetes, or heart disease, winter can feel especially harsh, as the cold air can easily irritate the lungs and aggravate existing inflammation,” clarifies Dr A Jayachandra, Clinical Director and Senior Interventional Pulmonologist, CARE Hospitals, Banjara Hills, Hyderabad.
Maintaining optimal gut health is crucial. It matters more than most people realise as 70% of the immune system lives in the gut. “A large part of our immune system sits in the gut, and when digestion is off, immunity often follows. During winter, when infections circulate more easily, a healthy gut helps the body respond faster and more appropriately. Simple habits like regular meals, enough fibre, and not overdoing processed foods go a long way in keeping immunity steady,” emphasises Dr Kamath.
Dr Ranjith suggests that for patients with a history of recurrent or protracted winter illnesses, a structured diagnostic approach is necessary to rule out underlying predisposing conditions beyond common, seasonal viral susceptibility. “Complete Blood Count (CBC) with Differentia will provide rapid screening for abnormalities in key immune cell lines. 25-Hydroxy Vitamin D Level is essential as its deficiency is strongly linked to impaired T-cell function and heightened susceptibility to respiratory infections.” He also suggests allergy evaluations.
Strengthening Immunity the Right Way
Nourish with sunlight and seasonal superfoods: Prioritise Vitamins C & D. Use winter produce like amla (Indian gooseberry), which has 20 times more Vitamin C than oranges, and citrus fruits like guava and lemons to support white blood cell production. Incorporate ginger, turmeric, and garlic into daily meals for their powerful anti-inflammatory and antiviral properties.
Stay active: Aim for 150 minutes weekly. Brisk walking, yoga, or indoor resistance training can help flush out bacteria and reduce stress hormones. If the weather is too harsh, try Surya Namaskar (sun salutations) or light aerobic routines at home to keep blood circulating.
Hydration and hygiene: Try drinking 2.1L to 2.6L of water daily. Sipping warm herbal teas or soups keeps nasal passages moist. Warm fluids are often easier to maintain in winter and help both hydration and comfort. Regular hand-washing for 20 seconds remains a fundamental tool for infection control.
Rest and stress management: Get 7–9 hours of quality sleep. High stress produces cortisol, which suppresses immune activity. Practice 10 minutes of deep breathing or meditation daily to keep your defenses high.
Humidity Control: Use a dehumidifier to keep indoor humidity below 50% to prevent mold and dust mite growth. Conversely, periods of intense, prolonged, unaccustomed exercise can lead to temporary, post-exertional immunosuppression, often referred to as an “open window” for infection. Balance and consistency are key to maintaining a heightened state of immune readiness.
Chronic Stress Modulation: Sustained psychological stress activates the hypothalamic-pituitary-adrenal (HPA) axis, leading to chronic elevation of cortisol, which suppresses crucial immune cell activity (e.g., natural killer cells). Integrating stress-reducing practices, such as mindfulness, cognitive restructuring, or daily meditation, is an essential component of immunological resilience.
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