Common cold

A cold is a mild infection of the nose and throat. More than two hundred viruses can cause one, and rhinoviruses are the commonest of them, so having had a cold gives little protection against the next.

Symptoms usually appear two or three days after catching the virus, are at their worst in the first two or three days, and settle over a week or two. Colds happen at any time of year, although some of the viruses that cause them are commoner in the cooler months.

Symptoms come on gradually rather than all at once:

• A blocked or running nose, and sneezing
• A sore or scratchy throat, and a hoarse voice
• A cough
• A headache and mild body aches
• Tiredness
• A mild fever, more often in young children
• Sometimes a reduced sense of taste or smell

Influenza, COVID-19 and a cold can look alike in the first day or two, but flu usually starts suddenly and leaves a person feeling far more unwell.

See a doctor within a few days if the symptoms last more than ten days without improving, if the fever lasts more than three days, if a cough carries on for more than three weeks, if things get worse after an initial improvement, or if there is asthma, a long-term lung condition or low immunity.

Colds are caused by viruses that infect the lining of the nose and throat. Rhinoviruses cause most of them, and several other families of virus cause the rest.

The virus spreads in droplets released when an infected person coughs, sneezes or blows their nose, and also on hands, door handles and shared objects. It reaches the next person when those hands touch the nose, mouth or eyes. People are most infectious in the first two or three days.

• Being a young child, or living with young children
• Close contact in a school, office, hostel or crowded home
• Contact with someone who has a cold in the first few days of their illness
• Smoking, or breathing other people's smoke
• Too little sleep
• A weakened immune system

Most colds cause nothing more than a week of misery. Sometimes the infection spreads or a bacterial infection follows, which can lead to:

• An ear infection, especially in small children
• A sinus infection
• A flare-up of asthma or chronic lung disease
• Bronchitis, or bronchiolitis in babies
• Pneumonia

• Washing hands with soap and water often, and before eating
• Covering the nose and mouth with a tissue when coughing or sneezing, then throwing it away
• Cleaning surfaces and things that many hands touch
• Not sharing towels, glasses or handkerchiefs with someone who has a cold
• Keeping away from others in the first few days of a cold
• Enough sleep, and avoiding tobacco smoke

A cold is recognised from the symptoms, and no test is needed for it.

A test for influenza or COVID-19 may be suggested when someone is at higher risk of serious illness, because those two have specific antiviral treatments. If a cough or fever drags on, a doctor may examine the chest or arrange further tests to look for another cause.

A cold gets better on its own. Rest, fluids and ordinary food are the mainstay. A salt water gargle, a warm drink with lemon and honey, and steam inhalation ease a sore throat and a blocked nose. Honey should not be given to a baby under one year.

A pharmacist can suggest paracetamol or ibuprofen for aches and fever, and decongestant drops or sprays for a blocked nose. Over the counter cold and cough mixtures do not shorten the illness and are not suitable for young children, so ask before giving anything to a child.

Antibiotics are not used for a cold. A doctor will consider them only if a bacterial infection such as a sinus or ear infection or pneumonia develops.