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Sore throat – Causes

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Sore throat – Causes



Causes of a sore throat 

A sore throat is often just one symptom of a bacterial or viral infection, such as the common cold.

The most common types of bacteria and viruses that may cause a sore throat include:



the rhinovirus, coronavirus and parainfluenza viruses, which normally cause the common cold – these are responsible for a quarter of all sore throats



different types of streptococcal bacteria – group A streptococcal bacteria cause 10% of sore throats in adults and nearly a third of sore throats in children, with groups C and G also thought to be a cause of sore throats



Other bacteria and viruses each tend to be responsible for less than 5% of sore throats. These include:



types A and B of the flu virus



adenovirus – which can also cause conjunctivitis, an infection in the eye



herpes simplex virus type 1 – which normally causes cold sores



the Epstein-Barr virus (EBV) – which normally causes glandular fever



There are many other, rarer, bacteria and viruses that are each responsible for less than 1% of sore throats.

Catching an infection

The bacterium or virus that causes a sore throat is usually caught from someone else who is already infected. For example, the common cold is spread through tiny droplets of fluid that contain the cold virus, launched into the air when someone coughs, sneezes or speaks.

If you breathe in one of these droplets or touch a surface that has the virus on it, and then touch your face, you may become infected.

Once you have caught an infection, two types of sore throat can develop. These are:



pharyngitis – when the area at the back of your throat (the oropharynx) becomes inflamed



tonsillitis – when your tonsils (the two lumps of tissue either side of your throat) become inflamed



 

Non-infectious causes

Less commonly, sore throats can have non-infectious causes. These include:



irritation caused by cigarette smoke or alcohol



irritation from a nasogastric tube (passed down your nose and into your stomach to provide liquid food if you can't eat solid food)



gastro-oesophageal reflux disease – a condition that causes acid to leak upwards from the stomach into the gullet



Stevens-Johnson syndrome – a very severe allergic reaction to medication



Kawasaki disease – a rare condition that affects children under five years of age



allergies – such as hay fever (an allergic reaction to pollen or spores) which, in rare cases, may also cause a sore throat



some blood disorders, such as leukaemia (cancer of the bone marrow) or aplastic anaemia (when the bone marrow does not produce enough blood cells)



oral mucositis (inflammation of the layer of tissue that lines your mouth), which can be caused by radiotherapy or chemotherapy (cancer treatments)



 

Introduction 

A sore throat (pharyngitis) is normally a symptom of a bacterial or viral infection, such as the common cold. In around a third of cases, no cause for the sore throat can be found.

If you have a sore throat, you may also have:



swollen tonsils (tonsillitis)



enlarged and tender glands in your neck



discomfort when swallowing



If your sore throat is caused by bacteria or a virus, you may also experience symptoms associated with common infectious conditions, such as:



a high temperature (fever) of 38C (100.4F) or over



aching muscles or tiredness



a headache



a cough



a runny nose



Treating a sore throat

Sore throats are common, especially in children and teenagers. This is because young people have not built up resistance (immunity) against many of the viruses and bacteria that can cause sore throats.

Most sore throats are not serious and usually pass without the need for medical treatment. Over-the-counter painkillers, such as paracetamolor ibuprofen, and self-care tips can usually help to relieve the symptoms of a sore throat without the need to see a GP.

Antibiotics are not usually prescribed for a sore throat, unless it is particularly severe or you are considered at risk of a more serious infection.

How long will a sore throat last?

A recent UK study looked at people who book a GP appointment for a sore throat (probably those with worse symptoms). The results found:



in 50% of cases, moderately bad symptoms of a sore throat had settled seven days after the onset of the illness



in 80% of cases, moderately bad symptoms of a sore throat had gone after 10 days



 

When to seek medical help

Make an appointment to see your GP if:



you have a persistent high temperature above 38C (100.4F), which does not go down after taking medication



your symptoms do not improve within a week



It's important to investigate the cause of your temperature because it may be the result of a more serious condition, such as:



epiglottitis – swelling and redness (inflammation) of the epiglottis (the flap of tissue at the back of the throat, underneath the tongue); if left untreated, it can cause breathing difficulties



quinsy – an abscess (a painful collection of pus) that develops between the back of the tonsil and the wall of the throat, usually caused by a bout of severe tonsillitis



Blood tests may be carried out if your GP suspects you have a type of viral infection called glandular fever (also known as infectious mononucleosis).

Emergency medical care

Contact your GP, local out-of-hours service or  111 as soon as possible if you have a sore throat and you:



are in severe pain



have difficulty breathing



are making a high-pitched sound as you breathe (stridor)



start drooling



have a muffled voice



have difficulty swallowing (dysphagia) or are not able to swallow enough fluids



If your symptoms are very severe or getting worse quickly, visit your nearest accident and emergency (A&E) department or call 999 for an ambulance.

At-risk groups

While most sore throats can be treated at home, some people are more at risk than others of developing complications from a sore throat, and may need additional treatment.

See your GP at the first sign of infection if you:



have HIV and AIDS (a virus that attacks the body's immune system)



have leukaemia (cancer of the bone marrow)



have asplenia (when your spleen, an organ behind your stomach, does not work properly or has been removed)



have aplastic anaemia (when your bone marrow does not produce enough blood cells)



are receiving chemotherapy



are taking an immunosuppressant medicine (which stops your immune system working) – for example, because you have had an organ transplant



are taking an antithyroid medication (to stop your thyroid gland producing too many hormones), such as carbimazole



are taking a disease-modifying anti-rheumatic drug (DMARD) – for example, to treat arthritis (a common condition that causes inflammation in the joints and bones)



 

Causes of a sore throat 

A sore throat is often just one symptom of a bacterial or viral infection, such as the common cold.

The most common types of bacteria and viruses that may cause a sore throat include:



the rhinovirus, coronavirus and parainfluenza viruses, which normally cause the common cold – these are responsible for a quarter of all sore throats



different types of streptococcal bacteria – group A streptococcal bacteria cause 10% of sore throats in adults and nearly a third of sore throats in children, with groups C and G also thought to be a cause of sore throats



Other bacteria and viruses each tend to be responsible for less than 5% of sore throats. These include:



types A and B of the flu virus



adenovirus – which can also cause conjunctivitis, an infection in the eye



herpes simplex virus type 1 – which normally causes cold sores



the Epstein-Barr virus (EBV) – which normally causes glandular fever



There are many other, rarer, bacteria and viruses that are each responsible for less than 1% of sore throats.

Catching an infection

The bacterium or virus that causes a sore throat is usually caught from someone else who is already infected. For example, the common cold is spread through tiny droplets of fluid that contain the cold virus, launched into the air when someone coughs, sneezes or speaks.

If you breathe in one of these droplets or touch a surface that has the virus on it, and then touch your face, you may become infected.

Once you have caught an infection, two types of sore throat can develop. These are:



pharyngitis – when the area at the back of your throat (the oropharynx) becomes inflamed



tonsillitis – when your tonsils (the two lumps of tissue either side of your throat) become inflamed



 

Non-infectious causes

Less commonly, sore throats can have non-infectious causes. These include:



irritation caused by cigarette smoke or alcohol



irritation from a nasogastric tube (passed down your nose and into your stomach to provide liquid food if you can't eat solid food)



gastro-oesophageal reflux disease – a condition that causes acid to leak upwards from the stomach into the gullet



Stevens-Johnson syndrome – a very severe allergic reaction to medication



Kawasaki disease – a rare condition that affects children under five years of age



allergies – such as hay fever (an allergic reaction to pollen or spores) which, in rare cases, may also cause a sore throat



some blood disorders, such as leukaemia (cancer of the bone marrow) or aplastic anaemia (when the bone marrow does not produce enough blood cells)



oral mucositis (inflammation of the layer of tissue that lines your mouth), which can be caused by radiotherapy or chemotherapy (cancer treatments)



 

Treating a sore throat 

Sore throats are not usually serious and often pass in three to seven days. There are some treatments you can use at home to relieve your symptoms.

When to see your GP

You should see your GP if you:



fall into one of the groups of people at risk of developing complications – this includes anyone with a weakened immune system due to medication, or a condition such as HIV



have persistent symptoms that are not improving or responding to self-care



Visit your nearest accident and emergency department (A&E) or call 999 for an ambulance if you have severe symptoms such as:



difficulty breathing or swallowing



severe pain



drooling



a muffled voice



a high-pitched sound as you breathe (stridor)



Painkillers

For treating sore throats, over-the-counter painkillers, such asparacetamol, are usually recommended. These may also help reduce a high temperature (fever).

You should not take aspirin or ibuprofen if you have:



asthma



current or past stomach problems, such as a stomach ulcer



current or past liver or kidney problems



Children under the age of 16 should never be given aspirin.

Take painkillers as necessary to relieve your pain. Always read the manufacturer’s instructions so you do not exceed the recommended or prescribed dose.

Self-care tips

If you or someone in your family has a sore throat, the tips below may help relieve the symptoms:



avoid food or drink that is too hot, as this could irritate the throat



eat cool, soft food and drink cool or warm liquids



adults and older children can suck lozenges, hard sweets, ice cubes or ice lollies



avoid smoking and smoky environments



regularly gargling with a mouthwash of warm, salty water may help reduce swelling or pain



drink enough fluids, especially if you have a fever



Steam inhalation is not recommended, as it's unlikely to help a sore throat and there is a risk of scalding.

Antibiotics

The use of antibiotics is not usually recommended for treating sore throats. This is because most sore throats are not caused by bacteria.

Even if your sore throat is caused by bacteria, antibiotics have very little effect on the severity of the symptoms and how long they last, and may cause unpleasant side effects.

Overusing antibiotics to treat minor ailments can also make them less effective in the treatment of life-threatening conditions. This is known as antibiotic resistance.

Antibiotics are usually only prescribed if:



your sore throat is particularly severe



you are at increased risk of a severe infection – for example, because you have a weakened immune system due to HIV ordiabetes (a long-term condition caused by too much glucose in the blood)



you are at risk of having a weakened immune system – there are some medications that can cause this, such as carbimazole (to treat an overactive thyroid gland)



you have a history of rheumatic fever (a condition that can cause widespread inflammation throughout the body)



you have valvular heart disease (a disease affecting the valves in your heart, which control blood flow)



you experience repeated infections caused by the group A streptococcus bacteria



 

Delayed antibiotics prescription

If your GP thinks you might need antibiotics, they may issue a prescription but ask you to wait up to three days for symptoms to improve.

If your sore throat gets worse, or has not improved after three days, you should have instructions to either:



take your prescription slip to a pharmacy



return to the GP surgery after three days to collect your medication



Recent studies show that complications of a sore throat are uncommon and usually not serious. A delayed antibiotic prescription seems to be as effective as an immediate prescription in reducing complications.

Using a delayed prescription provides similar benefits to an immediate prescription. Most importantly, this helps you to avoid taking antibiotics when they're not needed and helps prevent antibiotic resistance.

Tonsillectomy

A tonsillectomy is a surgical procedure to remove the tonsils (the two lumps of tissue on either side of your throat). If your child has repeated infections of the tonsils (tonsillitis), a tonsillectomy may be considered.

Persistent sore throat

If you have a persistent sore throat (one that lasts three to four weeks), your GP may refer you for further tests. This is because your sore throat may be a symptom of a more serious condition. Some possibilities are described below.

Glandular fever

If you are 15-25 years of age with a persistent sore throat, you may have glandular fever (also known as infectious mononucleosis, or mono). This is a type of viral infection with symptoms that can last up to six weeks.

Cancer

A persistent sore throat can also be a symptom of some types of cancer, such as throat cancer. This type of cancer is rare and mainly affects people over the age of 50. In the UK every year, 5,300 people are diagnosed with cancer of the oropharynx (the area at the back of your throat) or mouth.

Non-infectious causes

In some cases, a sore throat may be caused by substances that irritate the throat. Sources can include:



alcohol



cigarette smoke



an allergy – such as hay fever



gastro-oesophageal reflux disease (GORD) – when stomach acid leaks out of the stomach and into the gullet



You may find that avoiding these substances, or seeking treatment for an allergy or GORD, can help to reduce symptoms of a sore throat.

Giving up smoking

If you smoke, giving up will reduce irritation to your throat and strengthen your defences against infection.

The  Smoking Helpline can offer you advice and encouragement to help you quit smoking. You can call the helpline free of charge on 0300 123 1044 (England only) or visit the Smokefree website.

Preventing a sore throat

As sore throats are caused by bacterial or viral infections, they can be difficult to prevent.

If you have a sore throat caused by an infection, you can help prevent the infection spreading by practising good hygiene, such as washing your hands regularly and keeping surfaces clean and free of germs.