A cold – also called infectious rhinitis – is a very common viral infection of the nose and throat. Doctors call it a "self-limiting" condition, which means that it only lasts so long and goes away on its own.
In most people, colds are relatively harmless, but they have important social and economic impact. It is estimated that 40% of time lost from work and 30% of school absences are due to the common cold. Cold symptoms normally improve within 1 week, although some may last longer, especially in children.
There are over 200 different viruses responsible for causing colds. The most common type are the rhinoviruses, which cause about 40% of colds in adults. Colds occur most often from fall to early spring, when people tend to stay indoors – facilitating easy spread of these viruses.
Despite its name, colds are not caused by being exposed to the cold. Instead, common colds are infectious, and are passed from one person to another. The average adult gets about 2 to 3 colds per year, most often during the winter. Children may have 8 to 12 colds in a year because their body's defences aren't as developed.
The cold is usually transmitted by coming into contact with hands contaminated with nasal secretions, such as by shaking an infected person's hand and then touching your eyes, nose or mouth. Sneezing or coughing can also transmit the cold virus in droplets from an infected person's mouth or nose. Since cold viruses can live for several hours on hard surfaces, less commonly you can even get infected by picking up an object, turning a door handle, or answering a phone recently touched by a person with a cold. It then takes hold by being rubbed into the eyes, nose, or mouth.
Cold viruses infect the tissues that line the inside of the mouth, throat, and nose. These infected membranes become swollen or inflamed, and cold symptoms begin.
It usually takes anywhere from 1 to 3 days for symptoms to develop. The cold usually runs its course in about 7 to 14 days. Common symptoms include:
Colds may aggravate the symptoms of other conditions, such as asthma and chronic obstructive pulmonary (lung) disease (COPD). Colds can also lead to acute bacterial bronchitis, strep throat, pneumonia, or ear infections, especially for people with lung disease.
Fatigue, stress, or poor diet and poor health can result in more severe cold symptoms. Seniors especially tend to get more severe cold virus infections.
The cold virus can also infect other parts of the body. For instance, the eye infection known as pinkeye (mild conjunctivitis) can occur. Kids are especially prone to this, since they tend to wipe their noses with their hands and then rub their eyes.
A simple sniffle isn't usually a matter for the doctor. It is easy to self-diagnose a cold because they are so common. Many people say they have COVID-19 or the flu (influenza) when really they have a bad cold.
COVID-19 or the flu can be distinguished: they cause a high temperature and muscle aches and come on more quickly. In addition, fatigue is more common and severe with COVID-19 or the flu.
It's important that other conditions such as strep throat or bacterial chest infections (e.g., pneumonia) are not passed off as being "just a cold." If you start developing symptoms that aren't typical of the common cold – like coughing up thick brownish sputum, getting a bad headache, or developing a high fever (higher than 39°C or 102°F), or earache – you might have a more serious infection. In this case you should see your doctor. You should also see your doctor if your cold symptoms don't improve after 10 to 14 days.
We haven't yet found a way to kill the viruses that cause the common cold. Antibiotics are not effective against colds because colds are caused by viruses. Antibiotics are only helpful for bacterial infections.
Since there's no cure, a combination of coping strategies and medication can at least improve symptoms and keep you more comfortable.
Medications can be used to relieve cold symptoms, but they won't make the cold go away any faster. These include:
Health Canada does not recommend that cough and cold medications (with the exception of acetaminophen and ibuprofen) be given to children under 6 years of age. There is little evidence that these medications are effective and there have been rare reports of serious side effects, especially when too much of the medication is given. For children, saline nose sprays can help with nasal congestion. Honey may also be helpful for coughs and can be used in children over 12 months old.
Many cold medications contain several medications. Do not use more than one cold medication unless recommended by your doctor or pharmacist. This will help you avoid receiving too much medication or inappropriate medication(s).
There are many natural health products available advertised to prevent and treat colds, such as vitamin C, zinc, Echinacea and North American ginseng extract. However, they have not been proven to be effective.
The best way to prevent the common cold is to wash your hands frequently with soap and warm water, especially after touching objects that may have the virus on them and before preparing food or eating. When washing, remember to wash for at least 20 seconds (as long as it takes to sing the "Happy Birthday" song twice) and to wash the entire hand surface well. If water and soap are not available, you can also use an alcohol-based hand sanitizer – ensure you rub your hands until the product is dry.
You can also avoid close contact with people who have colds, especially for the first few days. Also, avoid rubbing your nose and eyes with your hands. Proper exercise, rest, and nutrition will help keep your body's defense system strong and able to fend off cold-causing viruses.
If you have a cold, cover your mouth and nose with a tissue when sneezing and coughing, and then dispose of the tissue. If you don't have a tissue, coughing into your elbow is better than covering your mouth with your hands – this way, you won't be putting the virus on your hands where it can easily be spread to others. Washing your hands frequently will also help prevent getting others sick.
*All medications have both common (generic) and brand names. The brand name is what a specific manufacturer calls the product (e.g., Tylenol®). The common name is the medical name for the medication (e.g., acetaminophen). A medication may have many brand names, but only one common name. This article lists medications by their common names. For information on a given medication, check our Drug Information database. For more information on brand names, speak with your doctor or pharmacist.