Colds are caused by viruses. More than 200 types of virus can cause a cold. Those most responsible for colds belong to one of two groups:

• rhinoviruses
• coronaviruses

Because a number of viruses can cause a cold, it's possible to have several colds, one after the other, as each one is caused by a different virus.

What do colds do to the body?

The viruses that cause a cold attack the lining of the nose and throat, inflaming these areas. As they become inflamed, they begin to produce more mucus, resulting in a runny nose and sneezing.

How is a cold spread?

Colds can be spread in several ways. If you have a cold and you sneeze, cough or speak, tiny droplets of fluid containing the cold virus are launched into the air. If these are breathed in by someone else then they may become infected.

Colds can also spread through direct and indirect contact. If you have a cold and you touch your nose or eyes and then touch someone else, you may pass the virus on to them. Alternatively, if you touch an object such as a door handle or telephone, the virus may be transferred to the object. If someone touches the object a short time later and then touches their mouth, nose or eyes, they may become infected.

In most cases, you will know when you have a cold from the symptoms.

When to seek medical advice

A visit to your GP is usually only necessary if:

• your symptoms persist for more than 14 days
• you have a high temperature (fever) of or above 39°C (102.2°F)
• you cough up blood-stained phlegm (thick mucus)
• you feel chest pain
• you have breathing difficulties
• you experience severe swelling of your lymph nodes (glands) in your neck and/or armpits

If you're concerned about your baby or an elderly person, or you have a long-term illness, such as a chest condition, arrange to see your GP. Alternatively, you can phone NHS Direct on 0845 4647, for an assessment.

In these circumstances your GP may carry out tests to make sure that your symptoms aren't being caused by another type of infection that may be more serious, such as pneumonia (a bacterial infection of the lungs) or glandular fever (a viral infection caused by the Epstein-Barr virus).

These tests may include:

• blood tests
• chest X-rays
• taking a sample of tissue from your throat using a swab (a small cotton bud with a plastic loop at the end), which is then checked for the presence of bacteria

Self care

In most cases, you will be able to treat the symptoms of cold yourself at home by using a number of self-care techniques. These are listed below.

• Drink plenty of fluids to replace any fluids you may have lost due to sweating and having a runny nose. 
• Get plenty of rest: there's no official guidance as to how long a person should stay off work or out of school. Most people usually know when they're fit enough to return to normal activities. 
• Eat healthily: a low-fat, high-fibre diet is recommended, including plenty of fresh fruit and vegetables (five portions a day).

Many children will lose their appetite when they have a cold. However, this is perfectly normal and it should only last for a few days. It's recommended that children with a cold only eat when they're hungry.

The remedies outlined below may also help to relieve your symptoms.

Steam inhalation

Steam inhalation involves sitting with your head over a bowl of hot water. Place a towel over your head, close your eyes and breathe deeply. Avoid getting the hot steam in your eyes.

The steam may help to ease your congestion by loosening mucus and making it easier to clear by blowing your nose. Adding menthol, eucalyptus, camphor, thymol or pine oil to the water may help to clear the passageways in your nose. 

Steam inhalation is not advised for children due to the risk of scalding. Instead, a child may benefit from sitting in a hot, steamy bathroom.

Gargling

Gargling with salt water can sometimes help to relieve the symptoms of a sore throat and nasal congestion.

Vapour rubs

Vapour rubs can help to soothe the symptoms of a cold in babies and young children. Apply the rub to your child’s chest and back. Don't apply it to their nostrils because this could cause pain and breathing difficulties.

Menthol sweets

Some people find that sucking a menthol sweet can help to relieve the symptom of a sore throat.

Nasal saline drops

Nasal saline drops or sprays can help relieve the symptoms of nasal congestion in babies and young children. Nasal saline drops contain salt water so they're thought to work in the same way as gargling salt, but they're often better tolerated in babies and young children.

Nasal saline drops or sprays are available from most pharmacists.

Over-the-counter cold medications

In England, over-the-counter (OTC) cold medicines are probably the most widely used type of medication. However, there isn’t much evidence that certain OTC medications are effective.

Painkillers such as ibuprofen, paracetamol and aspirin are the only type of medication known to be effective in treating colds.

Children who are under 16 years old or women who are breastfeeding should not take aspirin.

Decongestants (medications designed to reduce nasal congestion) may have some limited effectiveness against colds. However, don't use them for more than five to seven days because overuse can make the symptoms of congestion worse.

There's no evidence to support the use of antihistamines or cough syrups in treating a cold.

The use of antibiotics to treat a cold is not recommended. As almost all cases of cold are caused by a viral infection, antibiotics won't have any benefit, and may cause unpleasant side effects, such as nausea and diarrhoea.

Most OTC cold medications aren't suitable for children under six years old. If your child is unwell, talk to your pharmacist about the best option if you need an OTC medication.

Many OTC medications contain a combination of different medicines; typically a painkiller, such as paracetamol, and a decongestant, such as pseudoephedrine.

If you have recently taken an OTC cold medication, it may not be safe for you to take an additional painkiller. Read the manufacturer’s patient information leaflet carefully before taking the medication, and follow the recommended dosage instructions. 

More information about specific OTC medication is provided below.

Decongestants

Decongestants can be taken by mouth (oral decongestants) or they can be taken as a spray in your nose (nasal decongestants). They work by reducing the swelling in the passageways of your nose and they may also help to ease breathing.

There's limited evidence to show how effective decongestants are. This type of medication may only relieve some people from their cold symptoms. Also, when decongestants do work, they often only ease symptoms for a short period of time. 

However, decongestants are a safe and rarely cause serious side effects. If you use nasal decongestants frequently or for a long time, your congestion may end up getting worse.

Don't give any form of oral decongestant to a child under six years old, as it may cause adverse side effects.

Oral decongestants can cause a rise in blood pressure and heart rate, leading to a feeling of being more alert. Therefore, if you take OTC decongestants at bedtime, you may have problems sleeping at night. Oral decongestants, such as pseudoephedrine, phenylpropanolamine and phenylephrine are used in many OTC cold remedies.

Oral decongestants may interact with some antidepressants and beta-blockers. If you're taking either of these medicines, check with your GP or pharmacist before taking oral decongestants. If you have high blood pressure (hypertension), heart problems or glaucoma (a group of eye conditions that affect vision), check with your GP before using an oral decongestant.

Nasal decongestants work specifically on the nose. They're usually safe for adults and older children to use. Nasal decongestants, such as oxymetazoline, xylometazoline, phenylephrine and ephedrine are applied directly to the inside of the nose. They are available as nose drops or sprays.

Nasal decongestants shouldn't be used for more than five to seven days because using them for longer can actually make your congestion worse. If you're taking a type of antidepressant called a monoamine oxidase inhibitor (MAOI), you shouldn't use nasal decongestants.

Painkillers

Paracetamol, ibuprofen or aspirin can help to reduce a fever. They also act as painkillers (for children, use children’s liquid paracetamol). Always follow the manufacturer's instructions to ensure that the correct dose is given.

Ibuprofen and paracetamol can be taken alternately over the course of a day as long as you don't exceed the maximum dose for each. However, children mustn't be given both ibuprofen and paracetamol. You must either use one or the other. Using both could cause adverse side effects. Always follow the manufacturer’s instructions carefully.

Paracetamol, ibuprofen and aspirin are also included in some OTC cold medicines with other ingredients. Check with your pharmacist or GP before taking a cold remedy if you're taking any other painkillers.

Don't take ibuprofen if you have a history of stomach ulcer, indigestion, asthma or kidney disease. Aspirin should also not be taken by children who are under 16 years old or by women who are breastfeeding.

If you're pregnant, paracetamol – not ibuprofen – should be used for the short-term relief of mild to moderate pain and fever.

Zinc supplements

Taking zinc syrup, tablets or lozenges may be an effective treatment for the common cold.

A 2011 Cochrane review suggests that taking zinc supplements within a day of the symptoms starting will speed up recovery and lessen the severity of symptoms.

However, long-term use of zinc isn't recommended as it could cause side effects such as vomiting and diarrhoea.

More research is required to determine the recommended dose.

As there are so many different viruses that can cause the common cold, a vaccination against the condition hasn't been developed yet.

However, if you have a cold, there are things you can do to help prevent it from spreading.

You should:

• wash your hands regularly and properly, particularly after touching your nose or mouth and before handling food 
• always sneeze and cough into tissues as this will help to prevent the virus-containing droplets from your nose and mouth entering the air where they can infect others; throw away used tissues immediately and wash your hands 
• clean surfaces regularly to keep them free of germs 
• use your own cup, plates, cutlery and kitchen utensils  
• use disposable paper towels to dry your hands and face, rather than shared towels. As with tissues, always dispose of the paper towels after you have finished using them

A cold is a viral infection that affects the nose, throat and sinuses. There are more than 200 different cold viruses. While adults usually have two to four colds a year, children can catch as many as seven to 10.

Dr Rob Hicks, a GP in London, offers his advice. 

Is my child’s cold serious?

Colds aren't usually serious. However, babies, the elderly and anyone whose immune system is compromised can be at risk of developing more serious complications, such as a bacterial chest infection.

What are the differences between adult and child colds?

Children contract colds far more often than adults. Cold symptoms in a child may include a raised temperature (fever).

When should I take my child to the doctor?

Most colds get better on their own without treatment. Seek medical advice if:

• a baby aged less than three months develops a fever higher than 38°C
• cold symptoms last for more than 10 days, particularly if your child is coughing up green, yellow or brown sputum or has a fever – this could be a sign of a bacterial infection that needs treatment with antibiotics
• your child is finding it difficult to breathe. Seek medical help immediately from your surgery or local hospital
• your child complains of pain in the nasal passages after two to four days of home treatment
• your baby or child has, or seems to have, severe earache (babies with earache often rub their ears and seem irritable) as they could have an ear infection that may need antibiotic treatment
• your child complains of throat pain for longer than three or four days, or their throat pain seems unusually severe, as they may have bacterial tonsillitis that needs antibiotic treatment
• your child develops other symptoms such as pain or swelling in the face or in the chest, a headache or a very bad sore throat
• your child seems to be getting worse rather than better

Why won’t my doctor prescribe antibiotics for my child’s cold?

Antibiotics are used to treat infections caused by bacteria. Colds, however, are caused by viruses, which don’t respond to antibiotics. The overuse of antibiotics can lead to antibiotic resistance where symptoms don’t respond to treatment with antibiotics. The doctor is likely to prescribe antibiotics only if your child has developed a bacterial infection secondary to (on top of) a cold.