How to Prevent & Treat Colds & Flu

Cold viruses can live on surfaces for up to 24 hours (flu ~2 hours). Skin is an excellent barrier, but infection occurs when virus is transferred to mucosal entry points, particularly the eyes and then the mouth. Behavioral studies show people almost always touch their eyes/face shortly after shaking hands. Increasing awareness, washing/sanitizing hands before face-touching, and considering hand sanitizer after social contact can materially reduce infection risk.

Sleep deprivation and overtraining both suppress the innate immune system, increasing susceptibility to colds and flus. Regular exercise of ≤60 minutes at moderate to high intensity boosts natural killer cells, T cells, and beneficial cytokines, enhancing baseline immune readiness. By contrast, very long or extreme sessions (e.g., marathons, double sessions, >75–90 minutes hard work) temporarily depress immune function and raise stress/inflammatory markers to levels that increase infection risk.

The nasal passages have a specialized mucosal lining and microbiota that are particularly effective at neutralizing inhaled viruses. Nasal breathing warms and conditions air in ways that reduce viral embedding in mucosa. Mouth breathing—especially habitual mouth breathing during sleep—is associated with more upper respiratory infections in both children and adults. Consciously favor nasal breathing when not talking, exercising intensely, or eating, and address chronic mouth breathing if present.

When you feel healthy, daily or near‑daily exercise (20–60 minutes; one shorter HIIT session ~12 minutes weekly) and regular sauna use (e.g., 2–3 rounds of 15 minutes at ~176–210°F with brief cool‑offs) can upregulate leukocytes, natural killer cells, and heat shock proteins, priming innate immunity. However, if you already feel malaise, heavy limbs, throat tickle, or early cold/flu symptoms, pushing workouts or intense heat exposure increases stress load, impairs immune response, and tends to prolong or worsen illness. In that state, hot showers and extra rest are preferred.

A diverse gut—and nasal/oral—microbiome is tightly linked to robust immune function. Consuming 2–4 daily servings of low‑sugar fermented foods (e.g., refrigerated sauerkraut/kimchi, live‑culture yogurt, kefir, low‑sugar kombucha, brined pickles) improves microbiota diversity and immune support. A simple, no‑cost protocol: on waking, before brushing teeth, swish and swallow a small amount of water to move oral microbiota into the gut, potentially seeding beneficial strains (logic‑based, but not yet supported by randomized trials).