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Is a Sore Throat Contagious? Viral vs. Bacterial Symptoms

Is Sore Throat (Pharyngitis) Contagious?

Medically Reviewed on 1/29/2025

Can you catch pharyngitis?

Sore Throat (Pharyngitis)
Pharyngitis is a bacterial or viral infection of the pharynx.

Is a sore throat contagious? Yes, pharyngitis (viral and bacterial) is contagious and can be transmitted from one person to another. Usually, mucus, nasal discharge, and saliva can contain viruses and/or bacteria that can cause sore throat. Consequently, even kissing can cause the transfer of these organisms.

Unfortunately, some of these viruses and bacteria that cause sore throat can survive for some time on objects like towels, brushes, or even clothing, so contact with these contaminated items can spread the disease.

Sore throat caused by allergies, toxins, trauma, or cancers is not contagious. The focus of this article will be on sore throat caused by viruses and bacteria since these are the most common causes of sore throat.

What is the most common cause of pharyngitis?

Pharyngitis is the medical term for a sore throat. Pharyngitis is an inflammation of the pharynx (throat) that results in throat discomfort, pain, and/or throat scratchiness; in some individuals, it may cause painful swallowing.

Sore throat is usually caused by a viral infection and, less commonly, a bacterial infection, usually by group A streptococci (strep throat). Other causes of sore throat include inflammation due to allergy, toxins, or cancer.

Some doctors distinguish pharyngitis from laryngitis and/or tonsillitis, but others do not. Laryngitis is confined to the larynx (voice box) while tonsillitis is inflammation confined to the tonsils. Since it is not unusual for pharyngitis to spread to adjacent structures like the tonsils or larynx, it is not unreasonable to lump these inflammatory diseases together; however, the symptoms are slightly different for each disease.

There are three types of pharyngitis:

  1. Non-exudative (does not produce fluids like pus; this is the most common form of pharyngitis and usually caused by viruses)
  2. Exudative (produces a body fluid like pus; this usually suggests a bacterial cause)
  3. Ulcerative (production of small ulcers and/or a grayish membrane on parts of the pharynx). Ulcerative pharyngitis (mainly caused by bacteria) is infrequently seen but is considered to be a medical emergency.

How do I know if pharyngitis is viral or bacterial?

Pharyngitis can be both viral or bacterial. Depending on the cause of your sore throat, you may be more or less contagious. Prompt evaluation from a health care provider can help you diagnose your sore throat.

Pharyngitis can cause the pharynx (the throat) tissue to become swollen and reddish. Some people can develop a mild fever and have some difficulties speaking or swallowing food. Swollen lymph nodes and tonsils may enlarge and become tender. Those affected may feel excessively tired.

Laboratory studies can detect group A streptococci (rapid antigen detection). Other diagnostic tests can include throat cultures or the mono-spot test. A health care professional may help you determine the cause of your sore throat. In addition, some doctors use a specific set of criteria (Centor criteria) to determine the likelihood of a person getting strep throat (Streptococcal pharyngitis).

Should you stay home with pharyngitis?

Sore throat is transmitted from one person to another by bacteria or viruses in the infected person's saliva, mucus, and/or nasal discharge. People who are not infected just need to come in contact with these substances directly or indirectly by touching contaminated objects such as hairbrushes, towels, or toothbrushes.

Due to the severity of the contagious spread of pharyngitis, it is recommended to stay home if you have symptoms of the infection. Avoid close contact with others until you receive evaluation and treatment from a health care provider.

QUESTION

Which illness is known as a viral upper respiratory tract infection? See Answer

How long is pharyngitis contagious?

A sore throat caused by viruses is usually contagious as long as symptoms are present. Once the symptoms disappear, the person is usually no longer contagious and is "cured" of viral pharyngitis. However, the person may still be susceptible to other types of viruses that can cause pharyngitis.

Viral pharyngitis is typically contagious about one to two days before pharyngitis symptoms set in and 5 to 7 days after the symptoms resolve. However, certain viral infections, such as mononucleosis, may be contagious for several weeks.

Bacterial pharyngitis, such as strep throat, is usually contagious as long as symptoms are present, but in contrast to viral pharyngitis, antibiotics may reduce the period of infection, and the individual becomes no longer contagious about 24 hours after taking an effective antibiotic.

What happens if you don't treat pharyngitis?

Pharyngitis can lead to several complications if left untreated. These complications may include:

  • Rheumatic fever
  • Peritonsillar abscess
  • Guillain-Barré syndrome
  • Abscess
  • Infection spread

Due to the severity of the complications above, it is important to seek treatment for pharyngitis once symptoms begin.

If a person has a sore throat, they should contact a health care professional if they experience the following:

  • A sore throat that lasts for more than a week
  • If they develop a reddish rash
  • If the lymph nodes are swollen and tender, and/or if the person has a high fever

Go to an emergency department immediately if a person develops the following:

  • drooling,
  • shortness of breath, or
  • difficulty in eating or swallowing foods or liquids.

Frequently asked questions

  • How is a sore throat transmitted among people? A sore throat can be transmitted through respiratory droplets when an infected person coughs, sneezes, or talks. It can also spread through direct contact with the infected person's bodily fluids, such as saliva. You can get an infection through respiratory droplets if you breathe the droplets or touch something that contains the droplets and then touch your nose or mouth. Sharing personal items that have come into contact with infected fluids can also facilitate transmission.
  • What infections cause a sore throat and are they contagious? The most common infections that cause a sore throat are viral infections (caused by viruses such as the Epstein-Barr virus, coronaviruses, and adenoviruses) and bacterial infections (such as those caused by group A streptococcus, gonorrhea, and diphtheria). These infections are contagious and can spread through respiratory droplets, direct contact, or sharing contaminated items.
  • Is a sore throat caused by a cold contagious? Yes, a sore throat caused by a cold is contagious, as it is caused by viruses that spread easily through the air or by touching a contaminated surface.
  • Can a sore throat be a sign of a contagious illness? Yes, a sore throat is typically caused by contagious viruses and remains contagious as long as symptoms are present.
  • How long is a sore throat contagious? A sore throat is contagious as long as symptoms are present. Once the symptoms subside, it is no longer contagious. A sore throat typically lasts anywhere from a few days to weeks.
  • Are bacterial sore throats contagious? Yes, bacterial sore throats are contagious, and they spread through coughing, sneezing, talking, or shaking hands.
  • Can you spread a sore throat if you don't have other symptoms? You can spread a sore throat even if you don't have other symptoms. However, people who have symptoms are more contagious than those who don't.
  • How can you prevent spreading a sore throat to others? The best way to prevent spreading a sore throat to others is to avoid being around others when you are sick. Sneeze or cough into your elbows to avoid spreading the infection.
  • Is it safe to be around someone with a sore throat? It is definitely not safe to be around someone with a sore throat, as it is highly contagious and can spread easily.
Medically Reviewed on 1/29/2025
References
Acerra, J. "Pharyngitis." Medscape. <http://emedicine.medscape.com/article/764304-overview>.

Sore Throat (Pharyngitis). Cleveland Clinic. Accessed January 7, 2025. https://my.clevelandclinic.org/health/diseases/8274-sore-throat-pharyngitis