Sneezing, scratchy throat, runny nose—everyone knows the first signs of a cold, probably the most common illness known. Common colds can be cause by over 200 viruses.
Although the common cold is usually mild, with symptoms lasting 1 to 2 weeks, it is a leading cause of doctor visits and missed days from school and work in the United States. According to the Centers for Diseases Control and Prevention (CDC), 22 million school days are lost annually in the United States due to the common cold.
The Cold Season
In the United States, most colds occur during the fall and winter. This may relate to the opening of schools and the start of cold weather, which prompt people to spend more time indoors and increase the chances that viruses will spread from person to person.
Seasonal changes in relative humidity also may affect the occurrence of colds. The most common cold-causing viruses survive better when humidity is low—the colder months of the year. Cold weather also may make the inside lining of your nose drier and more vulnerable to viral infection.
One reason why there is no cure for the common cold is that more than 200 different viruses can cause cold symptoms. Some, such as rhinoviruses, seldom produce serious illnesses. Others, such as respiratory syncytial virus (RSV), produce mild infections in adults but can lead to severe lower respiratory tract infections in young children. (The lower respiratory tract includes the lungs.)
Rhinoviruses (from the Greek rhin, meaning “nose”) cause an estimated 30 to 50 percent of all colds. Scientists have identified more than 100 distinct rhinovirus types. For example, rhinovirus C was discovered only in 2007 and is found worldwide. Rhinoviruses grow best at temperatures of about 91ºF, the temperature inside the human nose.
Scientists think coronaviruses cause about 10 to 15 percent of all adult colds. They bring on colds primarily in the winter and early spring. Although many coronaviruses infect animals, only five infect humans, causing respiratory tract illness. How important coronaviruses are as a cause of colds is hard to assess because, unlike rhinoviruses, they are difficult to grow in a laboratory.
Adult cold symptoms also are caused by viruses that are responsible for other, more severe illnesses. These viruses are: adenoviruses, coxsackieviruses, echoviruses, orthomyxoviruses (including influenza A and B viruses, which cause flu), paramyxoviruses (including several parainfluenza viruses), RSV, and enteroviruses.
Researchers still haven't identified the causes of 20 to 30 percent of adult colds, presumed to be viral. Because current advances in technology are leading to new tools to diagnose diseases, however, the next decade undoubtedly will bring significantly greater understanding of the causes of the common cold.
Although a connection exists between the number of cases of the common cold and the fall and winter seasons, there is no experimental evidence that exposure to cold temperatures increases the chances that you will get a cold. There is also no evidence that your chances of getting a cold are related to enlarged tonsils or adenoids.
On the other hand, several research studies show that people who exercise regularly have a significantly reduced number of respiratory tract infections, such as the common cold, compared with those who don't exercise. Research also suggests that allergic diseases that affect the nose or throat and psychological stress may increase your chances of getting infected by cold viruses.
You can get infected by cold viruses by either of these methods.
- Touching your skin or environmental surfaces, such as office phones, that have cold viruses on them and then touching your eyes or nose
- Inhaling drops of mucus full of cold viruses from the air
Symptoms of the common cold usually begin 2 to 3 days after infection and often include:
- Sore throat
- Mucus buildup in your nose
- Difficulty breathing through your nose
- Swelling of your sinuses
Although fever is uncommon in adults, it is often found in children with colds and can climb to102ºF in infants and young children. Consult a healthcare provider if you or your child has a fever higher than 100.4°F.
Cold symptoms can last from 2 to 14 days, but if you are like most people, you’ll probably recover in a week to 10 days. If your symptoms return often or last much longer than 2 weeks, you might have an allergy rather than a cold.
High fever, significantly swollen glands, severe sinus pain, and a cough that produces mucus may be signs that you have a complication or more serious illness. If you have any of these signs, you should contact your healthcare provider.
There is no cure for the common cold, but you can get relief from your cold symptoms by
- Resting in bed
- Drinking plenty of fluids
- Gargling with warm salt water or using ice chips, throat sprays or lozenges for a scratchy or sore throat
- Using a decongestant or saline nasal spray to help relieve nasal sympsoms
- Using petroleum jelly to soothe a raw nose
- Taking aspirin or acetaminophen - Tylenol, for example - for headache or fever
Colds occasionally can lead to bacterial infections of your middle ear or sinuses, requiring treatment with antibiotics. However, you should not use antibiotics to treat a cold.
A word of caution: Several studies have linked aspirin use to the development of Reye’s syndrome in children recovering from flu or chickenpox. Reye’s syndrome is a rare but serious illness that usually occurs in children between the ages of 3 and 12 years. It can affect all organs of the body but most often the brain and liver. While most children who survive an episode of Reye’s syndrome do not suffer any lasting affects, the illness can lead to permanent brain damage or death. The American Academy of Pediatrics recommends children and teenagers not be given aspirin or medicine containing aspirin when they have any viral illness such as the common cold. Babies 6 months of age or younger should be given only acetaminophen, such as Tylenol, for pain relief.
Over-the-Counter (OTC) Cold Medicines
Nonprescription cold remedies, including decongestants and cough suppressants, may relieve some of your cold symptoms but will not prevent or even shorten the length of your cold. Moreover, because most of these medicines have some side effects, such as drowsiness, dizziness, insomnia, or upset stomach, you should take them with care.
Health experts have questioned the safety of nonprescription cold medicines in children and whether the benefits justify any possible risks from giving these medicines to children, especially those under 2 years old. In 2008, a Food and Drug Administration (FDA) panel recommended that nonprescription cold medicines not be given to children under 4 years old, because cold medicines don't appear to be effective for these children and may not be safe, especially for those under the age of 2.
Because many cold medicines contain multiple drugs, FDA also recommends being very careful in giving a child more than one cold medicine at a time, so as not to cause harm from too high a dose of cold medicines.
Over-the Counter (OTC) - Antihistamines
Nonprescription antihistamines may give you some relief from symptoms such as runny nose and watery eyes, which are symptoms commonly associated with colds.
Never take antibiotics to treat a cold because antibiotics do not kill viruses. You should use these prescription medicines only if you have a rare bacterial complication, such as sinusitis or ear infection. In addition, you should not use antibiotics “just in case,” because they will not prevent bacterial infections.
There are several ways you can keep yourself from getting a cold or passing one on to others.
- Because cold viruses on your hands can easily enter through your eyes and nose, wash your hands often and keep your hands away from those areas of your body.
- If possible, avoid being close to people who have colds.
- If you have a cold, avoid being close to people.
- When you sneeze or cough, cover your nose or mouth and sneeze or cough into your elbow rather than your hand.
Handwashing with soap and water is the simplest and one of the most effective ways to keep from getting colds or giving them to others. During cold season, you should wash your hands often and teach your children to do the same. When water isn’t available, Centers for Disease Control and Prevention(CDC) recommends using alcohol-based products made for disinfecting your hands.
Rhinoviruses can live up to 3 hours on your skin. They also can survive up to 3 hours on objects such as telephones and stair railings. Cleaning environmental surfaces with a virus-killing disinfectant might help prevent spread of infection.
Because so many different viruses can cause the common cold, the outlook for developing a vaccine that will prevent transmission of all of them is dim. Scientists, however, continue to search for a solution to this problem.
Echinacea is a dietary herbal supplement that some people use to treat their colds. Researchers have done studies on how exhinacea works in treating and preventing the common cold, but results have been mixed. Some researcher have found that the herb may help treat a cold if taken in the early stages, but others found that it had no effect.
Three large studies funded by the National Center for Complementary and Alternative Medicine, part of the National Institutes of Health, found that echinacea did not reduce the severity or length of the common cold.
Many people are convinced that taking large quantities of vitamin C will prevent colds or relieve symptoms. To test this theory, researchers have done several large-scale, controlled studies involving children and adults. So far, the data have not shown conclusively that large doses of vitamin C prevent colds. The vitamin may reduce the severity or length of symptoms, but there is no clear evidence of this effect.
In addition, taking large amounts of vitamin C over long periods of time in large amounts may be harmful. Too much vitamin C can cause severe diarrhea, a particular danger for elderly people and small children.
Some people use honey to treat coughs and to soothe a sore throat. A study conducted at the Penn State College of Medicine compared the effectiveness of a little bit of buckwheat honey before bedtime with that of either no treatment or dextromethorphan (DM), the cough suppressant found in many over-the-counter cold medicines. The results of this study suggest that honey may be useful to relieve coughing, but researchers need to do additional studies.
You should never give honey to children under 1 year of age because of the risk of infantile botulism, a serious disease.
Zinc lozenges and lollipops are available over the counter as a remedy for the common cold. However, evidence of their effectiveness has been mixed. A recent review analyzing a series of clinical trials suggests that zinc may slightly reduce the symptoms and duration of the common cold in otherwise healthy people, but the use of zinc lozenges was also associated with an increased risk of side effects such as nausea. Variations in the formulation of lozenges and the amount of zinc they contain also it difficult for health experts to make firm recommendations. Researchers need to do more studies to help find out how much zinc is the most effective, and whether zinc is helpful in all circumstances.
In 2009, the Food and Drug Administration warned consumers to stop using intranasal (in the nose) zinc products because some people reported a loss of smell after using these products.