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Symptoms and Causes

Along with throat pain, what symptoms generally accompany a sore throat?

Most people experience a sore throat (pharyngitis) at some point in their lives. It typically starts off as a mild discomfort, but can progress to cause significant pain. Along with a sore throat, these infections may cause other symptoms including runny nose, nasal congestion, and cough.

What typically causes a sore throat?

Pharyngitis can be due to a variety of factors, the most common of which are viral infections, bacterial infections, environmental allergens, and acid reflux. In rare cases, a sore throat can be due to more serious diseases of the throat and surrounding tissues, such as autoimmune diseases and cancer.

Of all these causes, which is the most common?  

The most common cause of a sore throat is a viral infection, such as those that cause colds and flu-like illnesses. Fortunately, most viral sore throats resolve by themselves in a few days without needing specific treatment.

How common are bacterial infections of the throat?

Bacterial pharyngitis is not as common as a viral infection, but it is an important consideration in certain age groups and populations because it can increase the risk for other diseases such as heart and kidney disease.

Streptococcus group A is the most common cause of bacterial pharyngitis, comprising 20-30% of sore throats in children and 5-15% of sore throats in adults. This type of infection is commonly referred to as “strep throat.”

Less common causes of bacterial pharyngitis are due to Streptococcus groups C and G and a bacteria called Fusobacterium necrophorum, which can cause a more serious illness called Lemierre’s syndrome.

Are some people at higher risk for contracting strep throat than others?

Streptococcal sore throat typically occurs in children 5-15 years of age and in adults who have school-aged children or are in frequent contact with children. In contrast, Streptococcal pharyngitis is rarely seen in children less than 3 years old.

Are there any complications of strep throat?

Medical providers treat bacterial pharyngitis with an antibiotic to shorten the duration of symptoms and to decrease the risk of complications. It is important to realize that strep throat is a self-limited illness which resolves by itself in a few days.

Untreated Streptococcal pharyngitis can, uncommonly, lead to tonsilitis, tonsillar abscess, and infections of the ear and lymph nodes. Treatment with antibiotics can also reduce the risk of developing rarer complications such as acute rheumatic fever and rheumatic heart disease. Antibiotic treatment, however, does not reduce the risk of poststreptococcal glomerulonephritis, an autoimmune disease of the kidney caused by the body’s exposure to the bacteria that can manifest weeks after an infection.

Antibiotic treatment for other, non-streptococcal bacterial infections will also improve symptoms and may decrease the risk of associated complications. Although infection with Streptococcus group C and G have not been conclusively linked to complications beyond the pharynx, infection with Fusobacterium can lead to peritonsillar abscess and, in extremely rare circumstances, a potentially fatal infection of the internal jugular vein called Lemierre’s syndrome.

Diagnosis

What symptoms differentiate strep throat from the usual viral causes?

Differentiating Streptococcal pharyngitis from viral causes without testing can be difficult. However, there are several clues that can help.

A sore throat accompanied by a runny nose, cough, pink eye, or diarrhea is most likely caused by a virus.

Conversely, a sudden onset of a sore throat or a fever without a cough or with a history of exposure makes Streptococcal infection more likely.

How do medical providers decide if someone needs a strep throat test?

To differentiate viral from bacterial causes of sore throat, clinicians frequently use a diagnostic scoring tool called the Centor Criteria. Those patients who have an intermediate score should be tested for Streptococcal pharyngitis.

The Infectious Diseases Society of America, however, recommends that patients < 3 years old not get tested, since streptococcal pharyngitis and rheumatic fever are rare in this population. The exception is when the child has been exposed to other household members with this strep.

In addition, since there is a high rate of asymptomatic strep carriers and because prophylactic penicillin has not been found to decrease subsequent infection with strep  they recommend against testing asymptomatic individuals who are in close contact with those infected with strep.

What kind of tests are available for detecting strep throat?

Clinicians can use two different types of tests to confirm a Streptococcal throat infection. The throat culture–a method where the medical professional swabs the back of the throat and tonsils and then sends the swab to the lab–is the most accurate, detecting 90% of bacterial throat infections. Unfortunately, it can take 1 or more days to receive results which can make the test impractical.

Alternatively, a rapid strep test, which provides results at the point-of-care within a few minutes, can be used. A sample is taken from the throat and tonsils and placed in a medium, which changes the color of a test strip if Streptococcal proteins are present. The accuracy varies from 70-90% depending on the test manufacturer.

Treatment

How is strep throat treated? Does everyone need antibiotics?

Streptococcal pharyngitis is treated with antibiotics, which can shorten the duration of symptoms by about 16 hours, decrease the chance of transmission to close contacts, and prevent the risk of complications such as peritonsillar abscess and acute rheumatic fever.

The decision of which antibiotic to prescribe takes into account effectiveness, safety, ease-of-use, and cost. Penicillin, taken twice a day for 10 days, remains the antibiotic of choice for those patients who are not allergic.

People who have been in contact with strep throat but have no symptoms do not need to be treated. Also, carriers of Streptococcus–people whose cultures are positive for the bacteria even when not ill–do not need to be treated unless they have recurrent bouts of symptomatic pharyngitis.

What are the best ways to manage the discomfort of a viral sore throat?

An irritated, dry throat can make it difficult to get through the day and, even, get a good night’s sleep. Fortunately, there are several strategies that can improve the discomfort.

The simplest approach is to gargle with salt water, which can relieve mild symptoms and moisten dry and irritated tissue. Other natural approaches include slippery elm (Ulmus rubra) or marshmallow root (Althea officinalis).  Used as a lozenge or in tea, these herbs create a soothing film over the irritated tissues of the pharynx. We frequently recommend Throat Coat tea which contains both of these ingredients.  

Studies support the use of ibuprofen (Motrin) or acetaminophen (Tyelnol) for relief of pain due to pharyngitis. Although aspirin has also been shown to relieve the discomfort associated with sore throat, experts advise avoiding its use in children due to the increased risk of Reye Syndrome, an inflammation of the brain and liver that occurs after a viral infection.

Finally, anesthetic lozenges or sprays with benzocaine or phenol (Cepacol, Chloraseptic) are over-the-counter medications that work by numbing the pharynx, alleviating discomfort for a few hours per application. Keep in mind, however, that lozenges should not be used in children less than 5 years old, as they can pose a choking hazard.

Beyond antibiotics for strep, can anything speed up recovery from a sore throat?

One meta-analysis (a review of multiple studies on a subject) looked at multiple different approaches to improving the symptoms of sore throat. Interestingly, antibiotics seemed to be among the least effective treatments for improving the symptoms of sore throat.

Other approaches such as 400 mg of ibuprofen (Advil, Motrin) showed around a 50%-80% decrease in pain from a sore throat after 2-4 hours. Similar results were seen with aspirin, with less improvement seen in those patients using paracetamol (similar to Tylenol). Of particular interest, one study showed that having received a flu shot decreased episodes of upper respiratory infection with sore throat by 25% during that flu season, suggesting an additional benefit of getting immunized every year.

Another meta-analysis looking at the use of corticosteroids (oral and injected) in addition to antibiotics and analgesics found that these decreased the time to pain relief by almost 5 hours and doubled the likelihood of complete resolution in 24 hours.

Prevention

How contagious is strep throat? When can someone be comfortable that they are no longer contagious?

Streptococcal pharyngitis is spread via respiratory droplets, saliva, and mucus. Breathing in these droplets, drinking from the same glass, sharing utensils, or touching your eyes or nose with exposed hands can spread the virus between you and an infected person.

The CDC recommends covering your mouth when coughing or sneezing, and also regular hand washing in order to decrease the risk of transmission.

Those with strep throat who are being treated with antibiotics are no longer contagious after 24 hours and can return to school or work, as their symptoms allow.

What is the best way to prevent transmission of infectious sore throats?

Both bacterial and viral throat infections are spread through respiratory droplets, saliva, and mucus. These fluids contain either the viral particles or the bacteria that can enter a healthy body through the mouth, nose, and eyes.

Lavarse las manos adecuadamente limita las probabilidades de propagar estas infecciones. Si entran en el cuerpo, un sistema inmunitario sano puede reducir la probabilidad de que estas entidades infecciosas provoquen enfermedades.

Enlaces útiles

Información sobre la faringitis estreptocócica y sus complicaciones (CDC)

Pautas de la Sociedad Estadounidense de Enfermedades Infecciosas para diagnosticar y tratar la faringitis estreptocócica (IDSA)

American Family Physician responde preguntas clínicas frecuentes sobre la faringitis estreptocócica (AAFP)

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