Common cold

The common cold, or simply a cold, is a viral infectious disease that affects the upper respiratory tract. It usually causes symptoms like coughing, sore throat, runny nose, sneezing, headache, fatigue, and sometimes fever. Most people get better in about one to two weeks, though some symptoms might last longer.

Over 200 different virus strains can cause a cold, with enteroviruses, especially rhinoviruses, being the most common. These viruses spread through the air or by touching things and then touching your face. Risk factors include going to child care facilities, not sleeping well, and feeling psychological stress.

There is no vaccine for the common cold because the viruses change quickly. To help prevent a cold, it’s important to wash your hands, avoid touching your face with unwashed hands, and stay away from sick people. While there is no cure, symptoms can be treated with zinc and nonsteroidal anti-inflammatory drugs like ibuprofen for pain. Antibiotics don’t work because colds are caused by viruses, not bacteria. The common cold is the most frequent infectious disease in humans, with adults getting two to three colds a year and children getting even more.

Signs and symptoms

A cold can make you feel tired, give you a runny nose, make you sneeze, and cause a sore throat. You might also have a headache or feel aches in your muscles. Sometimes, especially in little kids, there can be a fever. The cough from a cold is usually not as bad as a cough from the flu.

The mucus you blow out of your nose can be clear, yellow, or green, but this does not tell us if the sickness is from a virus or bacteria.

A cold often starts with feeling tired, chilly, sneezing, and a headache. A day or two later, your nose might run and you could start coughing. Most cold symptoms get worst after two to four days and then get better. Usually, a cold goes away in about one week to ten days, but sometimes it can last up to three weeks. Coughing can last for about eighteen days, and sometimes it continues even after the cold is over. In children, the cough can last longer than ten days in about half of the cases and more than twenty-five days in some cases.

Causes

The common cold is an infection of the upper respiratory tract caused by many different viruses. The most common are rhinoviruses, which have over 100 known types. Other viruses that can cause colds include coronaviruses, adenoviruses, enteroviruses, parainfluenza, and RSV. Sometimes, more than one virus is present at the same time. In fact, over 200 different viral types can lead to a cold. For some colds, we don't know which virus is the cause.

Colds are spread through tiny droplets in the air or by touching surfaces with the virus on them. When an infected person breathes, talks, or coughs, they release these droplets. If someone else inhales these droplets or touches their eyes or nose after touching a contaminated surface, they can get a cold. Viruses can stay on surfaces for a long time, over 18 hours for rhinoviruses.

Colds spread easily in places like daycare centers and schools because many children are close together and may not wash their hands well. These infections often go home with family members. Sitting close to someone with a cold can increase the chance of getting sick. Getting enough sleep and eating well can help protect against colds. Breastfeeding continues to be recommended even if a mother or baby has a cold.

Pathophysiology

When someone gets a cold, the symptoms like a runny nose or sore throat happen because their body is fighting off the virus. The body’s defense system reacts in different ways depending on the virus. For example, a virus called rhinovirus sticks to special parts inside the nose and throat, which tells the body to respond and causes cold-like symptoms. Another virus, called RSV, can spread through the air when an infected person coughs or sneezes. It starts in the nose and throat and can sometimes move deeper into the lungs. A third virus, called parainfluenza, usually makes the nose, throat, and airways swollen and red. In younger children, this can sometimes lead to a condition called croup because their airways are smaller.

Diagnosis

It can be hard to tell apart different kinds of colds because they often affect similar parts of the body, like the nose, throat, and lungs. Many people just figure out if they have a cold by how they feel. Doctors usually don’t try to find the exact virus causing the cold because it’s very difficult to tell just by looking at the symptoms.

Prevention

To help stop the spread of cold viruses, it’s important to wash your hands properly and use things like respirators and good ventilation. In places like hospitals, workers also wear gowns and gloves to stay safe. While face masks can help when you’re near someone who has a cold, we don’t know if staying far away from others makes much of a difference. There is no vaccine for the common cold because there are too many different viruses, and they change quickly. Regular hand washing is a good way to keep germs away, especially for kids. Taking zinc supplements doesn’t seem to prevent catching a cold.

Management

There is no cure for the common cold. To feel better, people can use medicines and other ways to help with their symptoms. Good ideas include resting, drinking fluids to stay hydrated, and gargling with warm salt water. These treatments often work because people believe they will help, known as the placebo effect. As of 2010, no medicines or herbal remedies have been proven to make a cold go away faster.

Medicines that may help with symptoms include pain relievers and fever reducers like ibuprofen and acetaminophen (paracetamol). However, it’s not clear if acetaminophen really helps with cold symptoms. Cough medicines are not recommended for children because they might not work and could be harmful. In 2009, Canada stopped allowing these medicines for children under six years old because of safety concerns. Some nasal sprays can help with a runny nose but don’t do much for congestion. It’s also not clear if drinking more fluids helps with symptoms.

Antibiotics don’t work against colds because colds are caused by viruses, not bacteria. Even so, antibiotics are sometimes prescribed, which can lead to antibiotic resistance. There are no effective antiviral medicines for the common cold. Zinc supplements might shorten a cold if taken early, but there are mixed opinions on whether to use them. Some alternative treatments, like nasal irrigation or herbal medicines, don’t have strong evidence to show they work. Taking vitamin C regularly might slightly shorten a cold, but vitamin D supplements haven’t been proven to help prevent or treat colds.

Prognosis

A common cold is usually not serious and gets better on its own. Most kids feel much better in about 10 days, and almost everyone is well within 15 days. Sometimes, people—especially very young children, older adults, or those whose bodies are having trouble fighting off germs—can get extra sick. This might lead to infections in the sinuses, throat, or ears. About 8 out of 100 cases can cause sinus problems, and about 30 out of 100 can cause ear infections.

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Epidemiology

The common cold is the most common illness that affects people around the world. Grown-ups usually get two to three colds each year, while children might get six to ten colds a year, and school children can even have up to twelve colds a year. As people get older, their bodies might not fight off germs as well, so they can get colds more often.

Many people think you can catch a cold just by being out in cold weather, but this isn’t true. Colds are caused by viruses, and these viruses tend to spread more during cold weather. We’re not completely sure why this happens, but it might be because cold air can change our bodies a little, make our immune systems weaker, or because dry air helps the virus stay in the air longer. It also might be because people spend more time close together indoors, especially children at school, making it easier for viruses to spread. Being cold doesn’t give you a cold, but if someone gets very cold and their body temperature drops a lot, they might be more likely to get sick.

History

The common cold has been around for a very long time. People have written about its symptoms and ways to feel better since before the 16th century BCE, in an old Egyptian medical book called the Ebers papyrus. The name "cold" started being used in the 16th century because the symptoms felt similar to being out in cold weather.

In 1946, a special group called the Common Cold Unit was created in the United Kingdom to study this illness. This is where scientists discovered the rhinovirus in 1956, the main cause of the common cold. They tried different ways to help people feel better, but only one method, using zinc gluconate lozenges, showed any real help. The unit closed in 1989 after many years of research.

Research directions

Scientists have tested medicines called antivirals to help treat the common cold, but as of 2009, none have been proven to work well enough to be approved for use. One drug called pleconaril shows promise because it may fight a group of viruses called picornaviruses, but it had safety problems when taken by mouth. Researchers are now studying an inhaled form of this drug to see if it might be safer. Scientists have also mapped out the genetic codes, or genomes, of all known strains of rhinoviruses, the main viruses that cause colds.

Societal impact

The common cold affects many people and costs a lot of money. In the United States, people visit doctors about 75 to 100 million times each year because of colds. This costs around $7.7 billion. People also spend money on medicines to help with cold symptoms, totaling about $3.3 billion each year. Many school days are missed because of colds, and parents and workers miss many days too. All together, colds cause more than $20 billion in lost work time each year in the United States. This is a big part of the time people miss from work.

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