How a cold spreads

A cold is a general term used to refer to a mild viral infection of the nose, throat, sinuses and upper airways. It is a self-limiting infection, which means it gets better by itself without the need for treatment.  

A cold can cause nasal stuffiness, runny nose, sneezing, a sore throat and a cough.

It is thought to be one of the most common health conditions: adults experience two to four colds a year on average, and children experience three to eight. A child's immune system is underdeveloped compared with an adult's, so they are more vulnerable to infection.

Women get more colds than men, possibly because they are more likely to come into close contact with children.

There are over 200 different viruses that can cause the common cold, so most people will become infected again at a later stage.

How a cold spreads 

A cold can be spread through:

• direct contact: for example, if you sneeze or cough, tiny droplets of fluid containing the cold virus are launched into the air and can be breathed in by others
• indirect contact: for example, if you sneeze onto a door handle and someone else touches the handle a few minutes later, they may catch the cold virus if they then touch their mouth or nose

It is thought that a person first becomes contagious 2-3 days before their symptoms begin and remains contagious until their symptoms have passed. So most people will be contagious for around two weeks.

The worse your symptoms are, the more contagious you will be. As your symptoms improve, you become less contagious.

Why colds occur in the winter

The common cold is more frequent during the winter months. 

It is possible that this is because people are more likely to stay indoors during winter, and be in close contact with each other. However, higher rates of colds have not been found in passengers on the London Underground, who spend a lot of time in close contact with each other.

Research carried out in 2005 suggested that cold weather could make people more vulnerable to developing a cold. However, further research is required to confirm this.

Outlook

Cold symptoms will ease within seven days without the need for treatment.

In the meantime, it is possible to relieve symptoms by taking over-the-counter medication such as paracetamol and drinking plenty of fluids

Symptoms of the common cold

Contagious

Contagious is when a disease or infection can be easily passed from one person to another.

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: this will help replace any fluids you may have lost due to sweating and having a runny nose
• take plenty of rest: there is no official guidance as to how long a person should stay off work or out of school. Most people will usually know when they are 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 is recommended that children with a cold only eat when they are hungry.

There is also evidence to suggest that there may be some truth in the traditional belief that eating chicken soup helps to relieve the symptoms of a cold. Researchers have found that chicken soup has mild anti-inflammatory properties that can help to reduce the inflammation and irritation that is associated with colds.

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

Steam inhalation

Steam inhalation involves sitting with your head over a bowl of hot water. Simply place a towel over your head, close your eyes and breathe deeply. Take care to 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. The salt can help reduce inflammation and 'draw out' any excess fluid that may be contributing to the symptoms of 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. Do not apply it to their nostrils because this could cause pain as well as 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 are thought to work in the same way as gargling salt, but they are often better tolerated in babies and young children.

Nasal saline drops or sprays are available from most pharmacists.

Over-the-counter cold medications

In Ireland, over-the-counter (OTC) cold medicines are probably the most widely used type of medication. However, there is surprisingly little evidence that certain OTC medications are effective.

In fact, 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 of age or women who are breastfeeding, should not take aspirin.

Decongestants (medications designed to reduce nasal congestion) may have some limited effectiveness against colds. However, they should not be used for more than five to seven days because they can actually make the symptoms of congestion worse.

There is 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 will not have any benefit, and may cause unpleasant side effects, such as nausea and diarrhoea.

Most OTC cold medications are not suitable for children who are under six years of age. Talk to your pharmacist if you require an OTC medication for a child who is under six years of age.

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

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

More information about specific OTC medications 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 is limited evidence to show how effective decongestants are and this type of medication may only provide some people with relief from the symptoms of a cold. Also, when decongestants do work, they often only ease symptoms for a short period of time. 

However, decongestants are a safe form of treatment and rarely cause any serious side effects. If you use nasal decongestants frequently or for a long time, you may end up worsening your congestion.

Do not give any form of oral decongestant to a child under six years of age, 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 are 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) also check with your GP before using an oral decongestant.

Nasal decongestants work specifically on the nose and are 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 should not be used for more than five to seven days because using them for longer than this can actually make your congestion worse. If you are taking a type of antidepressant called a monoamine oxidase inhibitor (MAOI), you should not use nasal decongestants.

Painkillers

Paracetamol, ibuprofen or aspirin can help to reduce a fever, and 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.

Do not 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 of age or women who are breastfeeding.

If painkillers are considered essential during pregnancy, paracetamol is the painkiller of choice for the short-term relief of mild to moderate pain and fever during pregnancy.

If a short-term painkiller is required during the first 30 weeks of pregnancy, ibuprofen could be taken. As with any medicine used during pregnancy, ibuprofen should be taken at the lowest effective dose for the shortest time necessary. Use of ibuprofen during the third trimester is not recommended, unless the treatment is under medical supervision.

Ibuprofen and paracetamol can be taken alternately over the course of a day as long as you do not exceed the maximum dose for each. However, children must not 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 are taking any other painkillers.

Throat lozenges containing flurbiprofen have been shown to relieve the symptoms of a sore throat that is associated with a cold.

Zinc supplements

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

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

More research is required to determine the recommended dose.

Preventing the common cold

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

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 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