Key Takeaways: Cold Exposure & Immune Function

Andrew Huberman addresses one of the most common questions about cold exposure: Can it make you sick? The answer reveals how timing, adaptation, and understanding your body's stress response determine whether cold builds resilience or depletes it.

The Core Insights

Cold Water Alone Won't Make You Sick

Brief cold exposure—one to ten minutes—does not directly cause colds or infections. Pathogens cause illness, not temperature. The myth persists because cold, dry air dries out mucosal barriers, making you more susceptible to viruses and bacteria already present in the environment.

Regular Cold Exposure Builds Immune Resilience

Six weeks of consistent cold exposure—three sessions per week—can increase immune cell production and markers like interleukin-6, T lymphocytes, and activated B cells. The mechanism: norepinephrine and epinephrine release, which activates immune pathways when deployed in acute, controlled doses.

Timing Matters: Avoid Cold When Sick

If you're already fighting an infection—feeling malaise, fatigue, fever—skip cold exposure entirely. Your body needs energy for recovery, not managing additional stress. Cold is hormetic: it strengthens you when healthy, depletes you when compromised.

The Wim Hof Study: Stress Modulates Inflammation

A 2014 PNAS study showed that cyclic hyperventilation before bacterial endotoxin injection reduced flu-like symptoms. The spike in norepinephrine dampened inflammatory immune responses, proving that nervous system activation can suppress symptomology—even if the pathogen remains.

Protocol Guidelines

1-10

minutes of cold exposure per session

sessions per week for adaptation

weeks to see immune marker increases

What to Do

When healthy: Do your cold exposure, but warm up within 10-30 minutes afterward. Hot shower, dry clothes, warm environment. Don't linger shivering in cold, dry air.
When slightly off: If you insist on cold exposure despite a minor sniffle, make warming up non-negotiable. Hot tea, sauna, bundled clothing.
When sick: Rest. No cold, no heat, no intense exercise. Let your immune system work without added stressors.
Breathe through your nose: Mouth breathing in cold, dry air dries out mucosal barriers. Nasal breathing filters pathogens and maintains mucus integrity.

The Bottom Line

Cold exposure is a tool, not a cure-all. Used correctly—regularly, when healthy, followed by proper warming—it can enhance immune resilience through controlled stress adaptation. Used carelessly—when sick, in dry air, without recovery—it becomes a liability.

The difference between benefit and harm isn't the cold itself. It's context. Timing. Understanding your body's state. That's where wisdom lives.

cold exposure immune system hormesis Andrew Huberman Wim Hof norepinephrine