How to Prevent & Treat Colds & Flu
Andrew Huberman, a Stanford professor, explains the biology of colds and flus, how the immune system combats them, and dispels common myths. He details science-supported behavioral, nutritional, and supplementation tools to enhance immune function, prevent illness, and recover faster.
Deep Dive Analysis
16 Topic Outline
Introduction to Colds and Flus
Common Cold: Types, Transmission, and Myths
Flu Virus: Types, Transmission, and Flu Shots
Tracking Health Trends to Avoid Sickness
Immune System: Physical Barriers
Immune System: Innate Response
Immune System: Adaptive Response & Lymphatic System
Foundational Tools to Enhance Innate Immunity
Importance of Nasal Breathing for Immune Health
Enhancing Gut Microbiome with Fermented Foods
Exercise When Feeling Sick vs. Preventing Sickness
Exercise Guidelines for Bolstering Immunity
Sauna Use to Enhance Immune System Function
Supplement Review: Vitamin C and Vitamin D
Supplement Review: Echinacea and Zinc
Supplement Review: N-acetylcysteine (NAC)
8 Key Concepts
Rhinoviruses
An umbrella category for cold viruses, causing nasal symptoms. There are over 160 different serotypes, which explains why there's no single cure and why individuals can get multiple colds within a year.
Viral Intelligence
The inherent drive of viruses to propagate from host to host, adapting to survive and infect more hosts, even though they lack a brain. This 'intelligence' guides their transmission and replication strategies.
Immune System Physical Barriers
The body's first line of defense against pathogens, including the skin, mucosal linings of the nose and mouth, and chemical agents on eye surfaces. These barriers physically block or chemically neutralize viruses and bacteria from entering the body.
Innate Immune System
The body's second line of defense, characterized by a rapid, generalized, and non-specific response to invaders like viruses, bacteria, or fungi. It deploys white blood cells (e.g., neutrophils, natural killer cells, macrophages) and chemical signals (e.g., cytokines, complement system) to combat infections broadly.
Adaptive Immune System
The body's third and most specific line of defense. It recognizes specific viral invaders and creates highly targeted antibodies (first IgM, then more specific IgG) to neutralize them. Crucially, it also maintains a memory of these specific battles for a faster response to future encounters with the same pathogen.
Complement System
A key component of the innate immune system found in blood plasma. It consists of chemicals that mark infected cells or viruses with a 'eat me' signal, directing other immune cells, like natural killer cells, to destroy them.
Cytokines
Chemical signals (e.g., interleukin-1, interleukin-6, tumor necrosis factor alpha) released by the immune system in response to infection. They draw blood flow and immune cells to the site of infection, contributing to the inflammatory response necessary for combating pathogens.
Mucolytic
A substance that loosens and thins mucus, making it easier to clear from body cavities such as the lungs, nasal passages, and sinuses. N-acetylcysteine (NAC) is an example of a compound with mucolytic properties.
10 Questions Answered
There isn't a cure because the 'cold virus' is actually over 160 different types (serotypes) of rhinoviruses, each with a different surface shape, meaning antibodies developed against one type won't work against another.
The cold virus is spread by breathing, sneezing, or coughing, often leading to transmission via contaminated hands touching eyes. Cold temperatures themselves do not cause colds; the virus is spread more in winter due to increased indoor contact.
Cold viruses are stable and can survive on surfaces for up to 24 hours, while flu viruses are less stable and typically die off after about two hours on surfaces.
People are contagious about 24 hours prior to the onset of symptoms for both colds and flus. With a cold, you're generally most contagious when you feel your worst, and with the flu, during the three days of peak symptoms.
The primary entry points are the eyes, nose, and mouth, often facilitated by unconsciously touching one's face with hands that have come into contact with the virus.
Nasal breathing creates a healthier environment (milieu) in the nasal passages, supporting a diverse nasal microbiome that is effective at combating incoming viruses, and it also heats the air in a way that reduces viral embedding.
If you're experiencing whole-body malaise or a throat tickle, it's best to rest, take a hot shower/bath, and get extra sleep, as pushing through exercise can compromise your innate immune system and prolong illness.
Despite common belief, current scientific evidence, including a retracted meta-analysis, suggests that high doses of vitamin C (6-8 grams/day) have only a small, non-robust effect, if any, on delaying or shortening colds, and are unlikely to be a good investment for this purpose.
Zinc supplementation, particularly at doses of 90-100 milligrams per day (no more than 120 mg/day), has been shown to shorten the duration of colds, with one study indicating a three times faster recovery rate. It should be taken with food to avoid gastric distress.
NAC is a precursor to glutathione (the body's master antioxidant) and a mucolytic, meaning it loosens mucus. Some studies suggest it may reduce the probability of contracting influenza and can relieve congestion during a cold.
18 Actionable Insights
1. Isolate When Symptomatic
If you are experiencing cold or flu symptoms such as coughing, sneezing, or runny eyes, stay home and avoid contact with others as much as possible, as you are contagious and exposing others to the virus.
2. Optimize Foundational Health
Maintain a robust innate immune system by prioritizing quality sleep, engaging in appropriate exercise, ensuring adequate nutrition (avoiding chronic caloric deficit), and managing chronic stress.
3. Strategic Exercise for Immunity
Engage in regular exercise of moderate to high intensity for 12-60 minutes per session, being careful not to exceed 75 minutes, to bolster your innate immune system by increasing immune cell circulation and activity. If feeling body malaise or sick, prioritize rest and avoid intense exercise to prevent compromising your immune system.
4. Practice Nasal Breathing
Consciously practice nasal breathing throughout the day and night, except when speaking, eating, or during intense exercise, to maintain a healthy nasal microbiome and regulate air temperature, which is crucial for combating incoming cold and flu viruses.
5. Avoid Face Touching
Be consciously aware and avoid touching your eyes, nose, or mouth with your hands, especially after shaking hands with others or touching public surfaces, as these are primary entry points for cold and flu viruses. Consider using hand sanitizer after contact if you cannot avoid touching your face.
6. Supplement Zinc for Colds
Supplement with 90-100 mg of zinc per day (no more than 120 mg/day), divided into doses and taken with a meal to avoid gastric distress, as it has strong data supporting its ability to combat colds and potentially reduce their duration by up to three times.
7. Consider NAC for Cold/Flu
Consider supplementing with N-acetylcysteine (NAC) as a mucolytic during a cold (e.g., 600-900 mg three times daily, avoiding close to sleep) or as a preventative (e.g., 600 mg twice daily for six months) to potentially reduce influenza contraction and support glutathione levels.
8. Regular Sauna for Immunity
Incorporate regular deliberate heat exposure, such as sauna sessions (e.g., three 15-minute rounds at 176-210°F with 2-minute cool-offs, or one 20-30 minute session), to increase innate immune system activity and leukocyte levels. Avoid hot saunas if you are already feeling sick.
9. Eat Fermented Foods
Support your gut microbiome by consuming two to four servings of low-sugar fermented foods daily, such as refrigerated sauerkraut, kimchi, kefir, kombucha, or live-culture yogurt, to promote microbiota diversity and bolster your innate immune system.
10. Track Health & Lifestyle
Keep a daily record of sleep quality, workouts, travel, and other life events, and review these patterns when you get sick to identify triggers or behaviors that precede illness, helping you learn what best protects your immune system.
11. Prioritize Electrolyte Hydration
Ensure proper hydration and adequate electrolytes (sodium, magnesium, potassium) by dissolving one packet of Element in 16-32 ounces of water first thing in the morning and during physical exercise, as these are vital for optimal brain and body function and cell functioning.
12. Utilize NSDR for Energy
Practice Non-Sleep Deep Rest (NSDR) or yoga nidra sessions, even for just 10 minutes, to greatly restore levels of cognitive and physical energy, as supported by scientific data.
13. Morning Oral Swish
Upon waking, before brushing your teeth, take a sip of water, swish it around your mouth, and then swallow it to introduce beneficial oral bacteria into your digestive tract, supporting the gut microbiome.
14. Post-Exercise Carbohydrate Intake
If training fasted or for longer durations (over 60-75 minutes), ingest complex carbohydrates and fruit within 45-60 minutes post-exercise to attenuate inflammation and prevent prolonged elevation of inflammatory molecules.
15. Adjust Exercise Post-Sleep Deprivation
If you experience one night of poor sleep but are not feeling sick, prioritize more sleep if possible; otherwise, engage in a reduced intensity and duration (25-50%) workout to offset negative effects, but remember exercise is not a substitute for sleep.
16. Supplement Vitamin D (Measured)
Supplement with 1,000-2,000 IU of Vitamin D daily to prevent deficiency and support immune function, especially if prone to respiratory infections, but consider getting your Vitamin D levels measured to determine if higher doses are needed.
17. Reconsider High-Dose Vitamin C
High doses of vitamin C (6-8 grams/day) are unlikely to be effective for treating or preventing colds and flus, as a meta-analysis supporting its benefits was retracted due to data analysis flaws. Ensure sufficient intake from food or foundational supplements instead.
18. Limit Echinacea Use
Echinacea has little scientific support for preventing or treating colds and flus, and high-dose, regular use may impede innate immune function; if used, reserve it for when feeling run down or during peak winter, and do not take it continuously for more than four weeks.
7 Key Quotes
The cold virus is made up of particles that are probably in the range of about five microns or so. So it's extremely small.
Andrew Huberman
If you are sneezing, if you are coughing, if you are still experiencing the symptoms of a cold, stay home, stay away from other people as much as possible.
Andrew Huberman
Your skin is a very important physical barrier against viruses such as the cold or flu virus getting into your body and infecting other cells and tissues.
Andrew Huberman
The adaptive immune system is the aspect of your immune system that recognizes, because the innate immune system told it, that something has infected the body at some level, at some organ or set of organs, and there's an emergency.
Andrew Huberman
Cortisol is fantastic, provided that it is elevated early in the day and not late in the day or evening.
Andrew Huberman
Exercise is a very potent tool. We know that. We know that in the context of changing aesthetics, like body mass composition, you know, increasing muscle, reducing fat. We know that in the context of reducing resting heart rate, reducing resting blood pressure. We know that in the context of all these other health metrics, here we're talking about using exercise as a very potent tool to increase the function of the innate immune system to keep you healthy, not just through the winter months, but around the year.
Andrew Huberman
If you're already sick and you have the symptoms of a cold or flu, you want to limit the amount of stress to your body. You want to get into bed and sleep. If you can't sleep, you want to relax. You do not want to exercise. You should not exercise.
Andrew Huberman
3 Protocols
Gut Microbiome Support Protocol (Daily)
Andrew Huberman- Consume 2-4 servings of low-sugar fermented foods (e.g., sauerkraut, kimchi, kefir, kombucha) per day. Ensure fermented foods are refrigerated and contain live cultures.
Oral Microbiome & Gut Health Protocol (Daily)
Andrew Huberman- Upon waking, before brushing your teeth, take a sip of clean water, swish it around in your mouth, and then swallow it.
Sauna Protocol for Immune Enhancement (Regular-ish Practice)
Andrew Huberman- Perform three rounds of 15 minutes each in a sauna heated between 176-210°F (or whatever can be safely tolerated).
- Separate each 15-minute round with a 2-minute cool shower or cool-off period outside the sauna.
- Complete 10 such sessions within a three-week period, spaced apart by at least a few days.