You catch a cold when a virus, most often a rhinovirus, enters your body through your nose, mouth, or eyes. This happens in two main ways: breathing in droplets from someone who’s coughing or sneezing, or touching a contaminated surface and then touching your face. Within 12 hours to three days of exposure, symptoms typically appear.
Airborne Droplets Are the Primary Route
When someone with a cold coughs, sneezes, or even talks, they release tiny virus-laden droplets into the air. If you’re close enough to inhale those droplets, the virus lands on the lining of your nasal passages and gets to work. Rhinoviruses latch onto a specific protein on the surface of your nasal cells, which acts like an unlocked door. Once attached, the virus tricks the cell into pulling it inside, where it hijacks the cell’s machinery to make copies of itself. Those copies spread to neighboring cells, and the infection takes hold.
This is why colds spread so easily in crowded indoor spaces like offices, classrooms, and public transit. The closer you are to a sick person, the higher the concentration of droplets you’re exposed to.
Surface Contact Is the Other Common Path
Cold viruses can survive on surfaces for several hours to days, depending on the material. Some viruses last longer on hard, non-porous surfaces like doorknobs, phones, and countertops, while others persist better on fabrics. You don’t get sick from touching the surface itself. The infection happens when you transfer the virus from your fingers to your nose, eyes, or mouth, which most people do dozens of times per hour without realizing it.
This makes shared objects like light switches, elevator buttons, keyboards, and shopping carts common transmission points. Handwashing reduces your risk of catching a respiratory infection like a cold by about 20%, according to CDC data.
Why Cold Weather Plays a Real Role
The old idea that “going out in the cold gives you a cold” isn’t quite right, but it’s not entirely wrong either. You need a virus to get sick, and cold air alone can’t cause an infection. However, the temperature inside your nasal passages drops when you breathe cold air, and research shows this matters more than people once thought.
A study in mouse airway cells found that at the cooler temperature typical of the nasal cavity (around 33°C versus the body’s core 37°C), cells mount a significantly weaker antiviral defense. They produce fewer of the signaling molecules that alert neighboring cells to fight back, and they’re slower to activate the genes responsible for blocking viral replication. In other words, rhinoviruses thrive in slightly cooler tissue not just because they replicate well there, but because your immune system’s first line of defense works less efficiently at lower temperatures.
Winter also pushes people indoors into closer contact, and dry heated air can reduce the moisture in your nasal passages, making them more vulnerable to infection.
When You’re Most Likely to Catch It
A person with a cold is contagious for roughly 7 to 14 days after symptoms begin, but the peak window for spreading the virus is around day two or three. This is when viral shedding is highest, meaning the infected person is releasing the most virus with every cough and sneeze. You can also catch a cold from someone who doesn’t feel sick yet, since the virus is replicating and potentially shedding before symptoms fully develop.
Children catch more colds than adults, partly because their immune systems haven’t encountered as many virus strains yet and partly because schools and daycares are ideal environments for transmission.
Why You Keep Catching Colds Year After Year
After you recover from a cold, your immune system does build antibodies against the specific virus strain that infected you. The problem is that rhinoviruses alone have over 100 distinct serotypes, and the antibodies you develop against one strain don’t protect you against another. On top of that, these viruses undergo antigenic drift, meaning they gradually mutate enough that even a strain you’ve fought off before can partially evade your immune memory. Add in the other families of viruses that cause colds (coronaviruses, adenoviruses, parainfluenza viruses), and there’s essentially an endless rotation of new infections your body hasn’t seen.
Cold vs. Flu vs. Allergies
All three can cause a stuffy nose and sneezing, but a few key differences help you tell them apart:
- Fever: Rare with a cold, common with the flu (often 100 to 102°F), and never present with allergies.
- Body aches: Slight with a cold, often severe with the flu, absent with allergies.
- Exhaustion: A cold might tire you out a bit, but the flu typically causes extreme exhaustion, especially early on. Allergies don’t cause this.
- Itchy, watery eyes: A hallmark of allergies that rarely occurs with a cold or flu.
- Duration: Colds and flu rarely last beyond two weeks. Allergy symptoms persist as long as you’re exposed to the trigger.
Practical Ways to Lower Your Risk
Handwashing is the single most effective everyday habit for avoiding colds. Washing with soap and water for at least 20 seconds reduces your chance of catching a respiratory infection by 16 to 21%. Alcohol-based hand sanitizer works well when soap isn’t available, though it’s slightly less effective against some non-enveloped viruses.
Beyond hand hygiene, keeping your hands away from your face makes a real difference, since your nose and eyes are the main entry points. Cleaning frequently touched surfaces at home when someone is sick helps limit spread. Getting enough sleep, staying hydrated, and managing stress all support your baseline immune function, making it harder for a virus to gain a foothold even when you are exposed.
If you do get sick, you’re most contagious on days two and three. Staying home during that window, or at least covering coughs and sneezes with a tissue or your elbow, significantly reduces the chance of passing the virus along.