What is a common cold?Common cold, also called viral rhinitis is a common upper respiratory tract infection caused by more than 200 viruses. It is a mild self-limiting illness, lasting about 7-10 days. It is a common cause of absenteeism from school and work. On average, an adult has about 2-3 episodes of common cold per year. Since it is caused by more than 200 viruses, there is no vaccine for the common cold.About 30-50 per cent of the common cold is caused by several types of virusesbelonging to the rhinovirus family. The rest is caused by viruses belonging to the coronavirus family (10-15 per cent), respiratory syncytial virus (5 per cent), viruses with seasonal variations like Influenza virus (5-15 per cent) and parainfluenza virus (5 per cent).Individuals who have less sleep, or have chronic sleep disturbance are at an increased risk of cold virus infection. Other risk factors include malnutrition and psychological stress. Moderate exercise may help lower the risk of cold virus infection.Signs and symptomsCommon cold usually starts with a sore throat, followed by nasal congestion, rhinorrhea (runny nose) and sneezing. Fever is usually low grade, which means temperature ranges between 98.7 to100.4 °F. Hoarseness of voice and cough also develop later. The symptoms usually start within 24-72hours of exposure even though it can occur as early as 10 hours after infection. Symptoms worsen from2 to 4 day and usually resolve by 7 days. However, hoarseness and cough may last longer than a week. Especially in smokers, cough can last up to 2-3 weeks. Peak viral shedding occurs on 2 or 3 day when symptoms peak and can last up to 2 weeks.Complications like acute sinusitis, asthma exacerbation, middle ear infection (acute otitis media) and lower respiratory tract infection can occur.Conditions which increase the severity of upper respiratory tract infection are cigarette smoking, immune deficiency states like HIV, chronic underlying disorders like obstructive lung disease and malnutrition.Difference between common cold and fluThe medical term for the flu is Influenza. Flu is usually a more severe form of respiratory tract infection. It is caused by viruses with seasonal variation (occurring in winter) like the influenza virus. Most of the symptoms of common cold also occur in Flu. Fever in Flu is high grade, the temperature ranging from 100-102 °F, sometimes even higher in young children. Generalized weakness or extreme tiredness, headache and body pain are common in the flu.Most of the flu symptoms are self- limited, resolving in a week. However, sometimes flu can also be severe requiring anti-viral medication and hospitalization. It can also cause death by causing lung infection called pneumonia. People at risk of severe flu symptoms include pregnant individuals, individuals above 65years of age or young children less than 5 years of age, immune- compromised individuals like people with uncontrolled Diabetes and people with kidney disease who are on hemodialysis..TreatmentThere is no specific treatment to shorten the duration or cure a common cold. It is treated symptomatically. Good rest with nighttime sleep of about 8 hours, plenty of fluids, warm saline gargle for the sore throat, steam inhalation for nasal congestion and tablet acetaminophen could help relieve the symptoms of a common cold.Antibiotics are NOT given to treat uncomplicated common cold as it is caused by viruses.Nasal inhalers containing only decongestants like pseudoephedrine and oxymetazoline can be used to relieve congestion. However, they should not be used for more than three days as they will worsen the nasal congestion.Cough medicine containing guaifenesin and dextromethorphan can be used with some relief but prolonged use may cause more side effects.Tips to prevent the common coldEating a good balanced healthy diet is important to prevent many illnesses, including the common cold. No vitamin or herbal product has been conclusively shown to impact the incidence of a common cold.Try to have a good night's sleep of about 7-8 hours. Moderate exercise (aerobic exercise, breathing exercise like Pranayama, Yoga etc.) may reduce the risk of cold virus infection.Since the mode of transmission is through hand contact, small droplets (aerosol transmission through sneezing and coughing) and large droplets (droplet transmission through close contact), it is recommended to wash your hands frequently with soap and, especially before touching the face, mouth or nose. The germs that can cause common cold usually live on surfaces, door handles or knobs for several hours. Wiping the surfaces with virucidal (kills the virus) disinfectants like phenol or alcohol can reduce the risk of transmission. Interestingly, the survival of the virus is not supported on a porous material like tissues and cotton handkerchief.When one is suffering from common cold and cough, he or she should cough into the elbow instead of the common practice of coughing into the hands, thereby preventing the spread of the virus. A cold inducing virus may remain viable up to 2 hours on human skin.To concludeIn these days of novel coronavirus pandemic, it is needless to say that one should maintain social distancing, wear a mask to cover the mouth and nose. One should also maintain good hand hygiene by washing hands frequently with soap and water especially before touching the face, mouth or eyes. This also prevents common cold, as it is also caused by viruses belonging to the coronavirus family in 10-15 per cent of cases.Dr. Suganthi Kumaran is a consultant Physician.