The most effective way to avoid catching a cold from someone is to wash your hands frequently, keep some distance when they’re coughing or sneezing, and avoid touching your face. Cold viruses spread primarily through airborne particles and contaminated hands, so targeting those two routes covers most of your risk. Here’s how to do it well.
How Cold Viruses Actually Spread
Cold viruses travel between people through four routes: direct physical contact (like a handshake), contaminated surfaces (doorknobs, phones, shared cups), large respiratory droplets, and fine aerosols that hang in the air. For years, surface contact was considered the dominant route, but a human challenge study of rhinovirus, the most common cold virus, found that airborne transmission alone was sufficient for the virus to spread, while transmission through contaminated surfaces alone was not observed.
That doesn’t mean surfaces are irrelevant. Rhinovirus survives on human skin for at least two hours with no significant drop in infectivity during that window. If someone sneezes into their hand and touches a light switch, the virus is waiting there. But the balance of evidence points to breathing in viral particles as the bigger concern, especially in poorly ventilated spaces.
How far those particles travel depends on what produced them. A sneeze can propel droplets more than 6 meters (about 20 feet). A cough sends them over 2 meters. Normal breathing pushes particles less than 1 meter. Keeping a few feet of distance from a sick person helps, but it won’t eliminate exposure entirely, especially in small or stuffy rooms.
When a Sick Person Is Most Contagious
People with colds shed the virus from their nose and throat for one to three weeks after infection. In adult studies, live virus was routinely recovered for about two weeks. Half of all shedding events wrapped up within seven days, but the first few days of symptoms, when sneezing and a runny nose are at their worst, are also when the most virus is being released into the environment.
A small percentage of infections, roughly 4.5%, involve prolonged shedding that lasts over 30 days. Some of these people have no symptoms at all. So even after someone says they feel better, they may still be mildly contagious for a while longer.
Handwashing Is Your Best Single Defense
Thorough handwashing reduces respiratory infections like colds by about 16 to 21% in the general population. The CDC recommends scrubbing with soap and water for at least 20 seconds, which removes significantly more germs than shorter washes. The friction matters as much as the soap: it physically dislodges viral particles from skin.
The key moments to wash are after being near a sick person, after touching shared surfaces (countertops, remotes, faucet handles), and before touching your eyes, nose, or mouth. Those three entry points are how the virus gets from your hands into your body. If you can break that chain, you eliminate one of the major infection routes.
When soap and water aren’t available, alcohol-based hand sanitizer works against rhinovirus. The concentration matters: you need at least 60% alcohol for it to be effective. Ethyl alcohol at 60 to 80% inactivates rhinovirus along with most other common respiratory viruses. Apply enough to cover your hands completely and rub until dry.
Improve Airflow in Shared Spaces
Since airborne transmission appears to be the primary route for cold viruses, ventilation is one of your strongest tools, especially when you’re sharing a home with someone who’s sick. Open windows when weather allows, even cracking them an inch makes a difference. Run exhaust fans in bathrooms and kitchens. If you have a portable air purifier with a HEPA filter, place it in the room where the sick person spends the most time.
The goal is to dilute the concentration of viral particles in the air. In one influenza transmission study, researchers attributed lower-than-expected infection rates specifically to higher ventilation in the study room, concluding that airborne spread was more significant than surface or droplet contact. The same principle applies to colds.
Masks Offer Modest Protection
Wearing a mask in close quarters with a sick person provides some benefit, though the effect is smaller than many people assume. In a large community trial, surgical masks reduced symptomatic infections by about 11%. Cloth masks showed no statistically significant effect. A separate trial comparing N95 respirators to surgical masks in healthcare workers found infection rates of 9.3% and 10.5% respectively, a difference that wasn’t statistically meaningful.
Masks are most useful in situations where you can’t avoid close, prolonged contact with someone who’s actively coughing or sneezing, like sharing a bedroom or a car. A surgical mask on the sick person reduces what they release into the air. One on you provides a partial filter for what you breathe in. Neither is a guarantee, but layering masks with handwashing and ventilation adds up.
Clean High-Touch Surfaces
Even though airborne spread appears dominant, surface contamination still plays a supporting role. Cold viruses can survive on hard surfaces like plastic, stainless steel, and countertops for hours. Focus your cleaning on the surfaces both you and the sick person touch frequently: door handles, light switches, faucet knobs, refrigerator handles, shared electronics, and bathroom fixtures.
Standard household disinfectants or disinfecting wipes are sufficient. You don’t need hospital-grade products. Clean these surfaces once or twice a day while someone in your home is sick, and wash shared items like towels and drinking glasses separately rather than reusing them.
Saline Nasal Spray as a Daily Habit
A simple daily saline nasal spray can reduce cold symptoms and may lower your chances of getting sick in the first place. In a controlled study of healthy adults, those who used a daily saline spray experienced an average of 0.7 upper respiratory infections over the study period compared to 1.0 infections without it. They also had significantly fewer days of nasal congestion and runny nose: 6.4 days versus 11.
Saline rinses work by flushing viral particles from the nasal passages before they can establish an infection and by keeping the nasal lining moist, which helps it function as a barrier. Over-the-counter saline sprays or a neti pot with distilled water both work. This is a low-cost, low-risk habit worth adopting during cold season or whenever someone around you is sick.
Practical Steps When You Live With a Sick Person
Living with someone who has a cold makes avoidance harder, but you can still meaningfully reduce your risk by combining strategies. Have the sick person stay in one area of the home as much as possible, and keep that room ventilated. Use separate hand towels and avoid sharing utensils or cups. Wash your hands every time you leave a shared space.
Sleep in a different room if you can. Nighttime breathing in a closed bedroom creates hours of sustained exposure to airborne virus. If separate rooms aren’t an option, crack a window or run a fan to keep air moving. These measures won’t make your risk zero, but each one chips away at the total viral dose you’re exposed to, and a lower dose means a better chance your immune system clears the virus before it takes hold.