Strep throat is a common and contagious bacterial infection. It appears most often in school-age children and their younger siblings.
What You Need to Know
- Strep throat is common, especially among children ages 5 to 15.
- Strep throat symptoms include sore throat, swollen glands and fever.
- It is diagnosed with a throat swab test.
- Once it is confirmed, strep throat can be treated with antibiotics to ease symptoms, control spread and prevent complications.
What Is Strep Throat?
Strep throat is an infectious illness. Its symptoms include a painful sore throat, fever and swollen glands.
Strep throat is common, especially in children ages 5 to 15, but older teens and adults can get it also, especially if they live or work with children in crowded conditions. Strep is rare in babies and young children under age 3.
Strep throat accounts for about 30% of sore throats in children, and 5% to 15% of sore throats in adults. Most sore throats in both children and adults are not strep throat, but viral infections caused by viruses.
Strep Throat Symptoms
The main symptom of strep throat in both adults and children is throat pain (pharyngitis) that may develop quickly, two to five days after exposure to the bacteria.
Other strep throat symptoms:
- Pain when swallowing
- Swollen glands in the neck
- Red spots (petechiae) on the roof of the mouth
- Red rash on the body (scarlet fever)
- Swollen tonsils
- Red or white streaks in throat or on tonsils
- Gastrointestinal symptoms such as stomach pain, nausea or vomiting. (These are more common in children.)
Does Strep Throat Cause Cough?
Cough is generally not a symptom of strep throat. Cough, hoarseness, runny nose, reddened eyes and other symptoms may point to a viral respiratory infection.
Can Someone Have Strep Without Fever or Sore Throat?
Yes. Some who have strep may be asymptomatic ― they may not feel sick ― but still capable of spreading the germ. However, a person is much more likely to be contagious if they have strep throat symptoms.
Strep Throat Diagnosis
To diagnose strep throat, a doctor uses one of two tests: a rapid strep test or a throat culture. Both start with the practitioner swabbing the patient’s throat with a cotton-tipped swab.
A rapid strep test can show results quickly but may not be as accurate as a throat culture, which tests to see if strep bacteria grow from the sample collected on the swab.
If a rapid strep test is negative in a patient with signs of strep throat, the doctor may recommend a culture to make sure the infection wasn’t missed on the rapid test. This is especially important in children, who can develop a complication of untreated strep throat called rheumatic fever. Antibiotics should not be used to treat a sore throat if a rapid strep test or throat culture is negative.
Sore Throat: Other Causes
Viral infections are a more common cause of sore throat than strep bacteria, so if strep tests are negative, a viral infection may be the culprit. Viral throat infections may include additional symptoms such as cough, runny nose or inflamed eyes. Antibiotic treatment does not kill viruses, so doctors generally do not prescribe antibiotics for viral throat infections.
Allergies, breathing dry or polluted air, gastroesophageal reflux disorder (GERD) and other conditions also can cause sore throat.
Is Strep Throat Contagious?
Yes, strep throat is contagious. The illness can spread quickly from person to person in households, classrooms, day care facilities, military training camps and other settings where groups of people are close to one another, particularly where children are present.
How Long is Strep Contagious?
People taking antibiotics for strep throat become less contagious over 24 to 48 hours. A person with untreated strep can infect others for two or three weeks.
How Do You Get Strep Throat?
The bacteria that cause strep throat are easily spread by the oral and nasal secretions and droplets of an infected person. These droplets can be released into the air when an infected person coughs, sneezes, talks, laughs or sings. The bacteria can live in traces of an infected person’s saliva or nasal discharge.
People catch strep throat from others by:
- Inhaling droplets in the air
- Touching an infected surface and then transferring the bacteria to the nose or mouth by hand
- Touching infected skin lesions
- Sharing cups, plates, glasses or eating utensils with an infected person
- Improper food handling (this is very rare)
When inhaled or swallowed, the strep bacteria invade the cells in the throat. Strep throat symptoms may appear two to five days after exposure.
Strep Throat Treatment
Antibiotics are the standard treatment for strep throat. When a person takes antibiotics for strep throat, symptoms are likely to improve within a day or two. However, it is very important to take the entire course of medications to ensure the infection is completely controlled and to lessen the chance of complications. Taking antibiotics as directed will also ease discomfort and help avoid contagious spread.
Strep A: The Germ That Causes Strep Throat
The bacteria that cause strep throat are strains of the Streptococcus family called strep A or Streptococcus pyogenes (S pyogenes). Strep A bacteria can cause other illnesses, such as:
- Impetigo: a skin infection that most commonly affects young children
- Scarlet fever: a red body rash associated with strep infection
- Cellulitis: a deep infection of the skin caused by bacteria
- Necrotizing fasciitis: a rare and potentially deadly infection
- Toxic shock syndrome: a bacterial infection of the blood that spreads toxins to the organs of the body
Invasive Strep Group A: iGAS
A form of strep A called invasive group A streptococcus, or iGAS, can cause aggressive infections such as cellulitis, necrotizing fasciitis and toxic shock syndrome. During the winter of 2022 – 2023, the CDC noted an increase in iGAS infections observed in children.
In addition to the conditions noted above, iGAS has caused a severe form of pneumonia, septic shock, meningitis, brain abscesses, empyema and even death.
Parents, caregivers and medical practitioners should remain alert for worsening symptoms of strep A infections in children and other at-risk groups, including adults with compromised immune systems, people who have just given birth and surgical patients.
Can I Get a Strep Vaccine?
No. Developing a vaccine for strep throat is challenging because there are many different strains of strep A, the bacteria that causes the illness. An effective vaccine would have to help the body create immunity from all the different kinds. Theoretically, this is possible, but more research and development will be needed before a strep throat shot can become a reality.
How Long Does Strep Throat Last?
Most cases of strep throat last three to five days. It’s important to remember that treatment with antibiotics is strongly recommended to reduce transmission, ease symptoms and avoid complications. Once a person with strep throat has been taking antibiotics for 24 hours and has no fever, they can return to work, school or daycare and not worry about infecting others.
Strep Throat Complications
Most children and adults with strep throat recover completely after taking all their antibiotics as directed. However, in rare cases, the disease can become more serious and complications can occur, including:
Rheumatic fever and rheumatic heart disease can cause inflammation that permanently damages to the heart valves, as well as painful knees and ankles, rashes, and other symptoms.
Kidney inflammation and autoimmune inflammatory arthritis affecting the joints are other potential problems that can arise from a strep infection.