Prioritize nasal breathing whenever possible (unless eating, speaking, or exercising hard) because nasal passages are a primary defense site against viral, fungal, and bacterial infections, with hairs, mucus, and microbiome trapping pathogens and protecting deeper physiology.
Use an air humidifier in indoor environments, especially at night, to keep nasal passages and respiratory pathways sufficiently humidified and healthy, as dry air (common with indoor heating) compromises their defense against colds and flus.
Maintain physical distance from individuals who are sneezing or coughing, as physical proximity directly increases the probability of contracting a cold or flu.
Assume anyone who is sneezing or coughing due to a cold or flu is contagious, regardless of their claims about being early or late in their illness, as data suggests they are contagious whenever these symptoms are present.
Wash your hands thoroughly after wiping your face or nose, or using tissues, especially if you are sick, to prevent transmitting cold or flu viruses through contact like handshakes.
If you are sick with a cold or flu, avoid attending events or being in close proximity to others to prevent transmitting your illness, as it is considered polite and responsible to try and not get others sick.
Cover your mouth and nose when sneezing or coughing, ideally into your elbow if a tissue is unavailable, to prevent the spread of germs to others.
After exercising outdoors in cold, dry weather, rehydrate your nasal and oral passages (e.g., with a hot shower, steam room, or humidifier) before going indoors and being around others, as dried passages increase susceptibility to illness.
If you experience a chill from being outside in cold weather, warm up by taking a hot shower, bath, or using a sauna upon returning indoors, as there’s a relationship between core body temperature and susceptibility to cold and flu.
Recognize that fever is an adaptive immune response designed to heat up and destroy viruses; consider this when deciding whether to take medication to lower a fever, while also being aware of the dangers of highly elevated body temperatures.