Is Sore Throat (Pharyngitis) Contagious?

Sore throat caused by a viral or bacterial infection is contagious. Other cases of sore throat caused by smoking, allergies or environmental irritants are not contagious.

Sore throat (pharyngitis) is a symptom typically caused by a viral or bacterial infection. Strep throat is a specific kind of sore throat caused by group A Streptococcus (GAS) bacterium. 

What Are Symptoms of Sore Throat (Pharyngitis)?

Symptoms of a sore throat may include: 

• Throat pain
• Pain on swallowing
• Difficulty swallowing
• Scratchy sensation in the throat
• Swollen, red tonsils
• Swollen glands in the neck
• Hoarseness or voice changes

Most cases of sore throat (pharyngitis) are caused by viruses, usually viruses that cause upper respiratory infections, such as the common cold. If a sore throat is caused by a virus, cold symptoms that may accompany a sore throat can include:

• Runny or stuffy nose 
• Eye irritation or redness of the eyes
• Cough
• Soreness in the roof of the mouth
• Fever
• Feeling unwell (malaise)

About 10% of cases of sore throat are strep throat, caused by group A Streptococcus (GAS) bacterium. Additional symptoms of strep throat include:

• Sore throat that may come on quickly
• Fever (temperature greater than 100.4ºF, or 38ºC)
• White patches of pus on the side or back of the throat
• Tiny, red spots on the roof of the mouth 
• Streaks of pus on the tonsils
• Headache
• Stomach pain
• Nausea
• Vomiting 
• Rash (scarlet fever) 
• No cough, runny nose, or irritation/redness of the eyes

Sore throat (pharyngitis) is typically caused by a viral or bacterial infection. 

Viruses that can cause sore throat include: 

• Common cold viruses 
• Influenza
• Coronavirus disease 2019 (COVID-19)
• Croup 
• Mononucleosis (“mono”)
• Measles
• Chickenpox

The most common bacterial cause of sore throat is group A Streptococcus (GAS) bacterium, which is responsible for strep throat. 

Other causes of sore throat can include: 

• Vocal trauma such as from shouting too much, cheering, or straining the voice 
• Inhaling harsh chemicals, such as cleaners or gasoline
• Environmental irritants (pollution)
• Smoking or vaping
• Allergies
• Acid reflux
• Use of asthma inhalers
• Medical problems
  • Abnormal growths on the vocal cords
  • Muscle disorders affecting the voice box
  • Throat cancer 

Sore throat (pharyngitis) in itself is a symptom and is not contagious, however, the viruses and bacteria that usually cause a sore throat are contagious. 

Viruses and strep throat (a bacterial infection) are contagious. When a person who has a viral infection or strep throat coughs or sneezes, respiratory droplets that contain the bacteria are released into the air. 

Viruses and strep can be transmitted when people:

• Inhale respiratory droplets released after an infected person coughs or sneezes
• Touch something with droplets on it and then touch their mouth or nose
• Share glasses, plates, or utensils with an infected person
• Touch sores on the skin caused by group A strep (impetigo)

Patients with strep throat are generally considered no longer contagious after 24 hours of antibiotic therapy. However, if untreated, strep throat can remain contagious for up to 3 weeks.

Sore throat (pharyngitis) is diagnosed with a history and physical examination of the throat. 

If strep throat is suspected, tests may include: 

• A rapid strep test: This involves swabbing the throat and running a test on the swab to see if strep bacteria are present in the patient’s throat. Results are usually available in about 15 minutes.
• A throat culture: In some cases, the rapid strep test results are negative but a doctor may still suspect strep infection is present. In this case, a throat culture swab may be obtained. This test can take 2-3 days to yield results but it is more accurate than a rapid strep test.

If sore throat (pharyngitis) is caused by a virus, there is no specific treatment. Treatment is aimed at relief of symptoms. 

To relieve symptoms of a sore throat caused by a virus, treatment may include: 

• Over-the-counter pain relievers such as acetaminophen (Tylenol) or nonsteroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen (Advil, Motrin) or naproxen (Aleve)
• Salt-water gargle: combine 1/4 to 1/2 teaspoon salt per 1 cup warm water
• Throat sprays that contain containing topical anesthetics (e.g., benzocaine, phenol) may help relieve sore throat pain
• Lozenges (cough drops) containing topical anesthetics can ease throat pain and relieve dryness (lozenges are not recommended for young children; they can be a choking hazard)  
• Sipping warm beverages (e.g., tea, chicken soup), cold beverages, or eating cold or frozen desserts (e.g., ice cream, popsicles) 

Strep throat is a bacterial infection and is treated with antibiotics. The first line choices are usually penicillin or amoxicillin. Other antibiotics may be used in people allergic to penicillin. If antibiotics are prescribed, take the entire dose as prescribed, even if you feel better before you have finished all the medication.