ConditionInfections
Strep Throat
Strep throat is a throat and tonsil infection caused by group A Streptococcus bacteria. It typically causes a sudden, painful sore throat, pain on swallowing, fever, swollen tender neck glands and red tonsils with white patches, usually without a cough or runny nose. It is most common in children aged 5 to 15. A rapid strep test or throat culture confirms it. Antibiotics, usually penicillin or amoxicillin, speed recovery, stop spread after 12 to 24 hours and prevent complications such as rheumatic fever.
Also called: Streptococcal pharyngitis, strep tonsillitis, group A strep infection of the throat
At a glance
- Cause
- Group A Streptococcus bacteria.
- Who gets it
- Mostly children 5 to 15; causes up to about 3 in 10 sore throats in children and 1 in 10 in adults.
- Symptoms
- Sudden sore throat, painful swallowing, fever, swollen neck glands, white patches on tonsils, often no cough.
- Diagnosis
- Rapid strep test; throat culture if negative in children.
- Treatment
- Penicillin or amoxicillin for 10 days; alternatives for allergy.
- Contagious
- Until 12 to 24 hours after starting antibiotics.
When to get help
Call 911 or go to the ER
- Difficulty breathing, noisy breathing, drooling or being unable to swallow saliva
- A severe one-sided throat swelling with a muffled voice and difficulty opening the mouth (possible peritonsillar abscess)
- A stiff neck, confusion or a rash that does not fade when pressed, with fever
See a doctor within a day or two
- Sudden sore throat with fever and no cough, especially in a child: get a strep test the same day
- Sore throat with a red, rough, sandpaper-like rash (possible scarlet fever)
- Not drinking enough or very few wet diapers or trips to the bathroom
- No improvement after 48 hours of antibiotics
Book a routine appointment
- Joint pain and swelling, chest pain or jerky movements weeks after a sore throat
- Dark, cola-colored urine or puffy face 1 to 3 weeks after strep
- Frequent recurrent strep infections
Usually safe to manage at home
- Sore throat with a cough, runny nose, hoarseness or pink eye, suggesting a virus, improving within a few days
What causes strep throat
Strep throat is caused by Streptococcus pyogenes (group A strep). It spreads through:
- droplets from coughs and sneezes
- sharing cups, utensils or food
- touching surfaces and then the mouth or nose
Symptoms usually start 2 to 5 days after exposure. Strep throat is most common in late fall through spring and in schools and childcare settings. Some people carry strep in their throat without being ill.
Symptoms
- sudden sore throat
- pain when swallowing
- fever of 38.3 °C (101 °F) or higher
- red, swollen tonsils, sometimes with white patches or streaks of pus
- tiny red spots on the roof of the mouth (petechiae)
- swollen, tender lymph nodes at the front of the neck
- headache
- stomach pain, nausea and vomiting, especially in children
- a sandpaper-like rash in some, which is scarlet fever
Strep throat vs viral sore throat
Most sore throats are caused by viruses and do not need antibiotics.
| Feature | Strep throat | Viral sore throat |
|---|---|---|
| Onset | Sudden | Gradual |
| Cough, runny nose, hoarseness | Usually absent | Common |
| Fever | Often high | Mild or none |
| Neck glands | Swollen and tender at the front | Mildly swollen |
| Tonsils | Red, swollen, white patches | Red, sometimes patches |
| Age | 5 to 15 most common | Any age |
| Antibiotics | Helpful | Do not help |
Mononucleosis can look very similar, with white patches and swollen glands, but causes more fatigue and swollen glands at the back of the neck, and a strep test is negative.
Diagnosis
Doctors use symptom scores (such as the Centor or McIsaac criteria: fever, absence of cough, swollen tender neck glands, tonsil exudate and age) to decide who needs testing.
- Rapid antigen detection test: a throat swab with results in minutes
- Throat culture: used to confirm a negative rapid test in children and teenagers, because rapid tests can miss cases
- Molecular (PCR) tests: highly accurate rapid tests
Testing is not routinely recommended for children under 3, in whom strep throat and rheumatic fever are uncommon, unless they have other risk factors.
Treatment
Antibiotics
- Penicillin V or amoxicillin for 10 days is first-line. Strep remains reliably sensitive to penicillin
- A single injection of benzathine penicillin is an alternative
- For penicillin allergy: cephalexin or cefadroxil (if the allergy is not severe), or clindamycin or azithromycin
- Finish the full course even if feeling better
Symptom relief
- acetaminophen (paracetamol) or ibuprofen at the label dose for pain and fever; no aspirin for children or teenagers
- warm or cold drinks, ice pops and soft foods
- salt-water gargles for older children and adults
- throat lozenges for older children and adults
- rest
Most people feel better within 1 to 2 days of starting antibiotics.
Complications
Antibiotics greatly reduce the risk of complications:
- peritonsillar abscess: a collection of pus beside a tonsil
- ear infections and sinusitis
- rheumatic fever: inflammation of the heart, joints, skin and brain that can permanently damage heart valves
- post-streptococcal glomerulonephritis: kidney inflammation
- scarlet fever
- rarely, invasive strep infections
Recurrent strep throat
Some children get frequent strep infections. Options include confirming each infection with a test, checking for strep carriage, and considering tonsillectomy for children with very frequent documented episodes, for example 7 or more in a year, 5 or more per year for 2 years, or 3 or more per year for 3 years.
Prevention
- wash hands often
- do not share cups, utensils or toothbrushes
- cover coughs and sneezes
- stay home until fever-free and after at least 12 to 24 hours of antibiotics
- replace your toothbrush after starting treatment
Frequently asked questions
How do I know if I have strep throat or a virus?
Strep throat usually starts suddenly with a sore throat, painful swallowing, fever and swollen neck glands, without a cough or runny nose. Viral sore throats often come with cough, runny nose, hoarseness or pink eye. A rapid strep test confirms the cause.
How long is strep throat contagious?
Strep throat is contagious until about 12 to 24 hours after starting antibiotics. Without treatment, people can remain contagious for 2 to 3 weeks. Children can usually return to school once they have been on antibiotics for at least 12 hours and are fever-free.
Can strep throat go away without antibiotics?
Symptoms may improve on their own within a week, but untreated strep throat carries a risk of complications such as rheumatic fever and abscesses, and it stays contagious longer. Antibiotics are recommended for confirmed strep throat.
Can adults get strep throat?
Yes. Adults get strep throat less often than children, but it is common in parents of school-age children and people who work with children. Symptoms and treatment are the same.
What does strep throat look like?
The throat and tonsils are bright red and swollen, often with white patches or streaks of pus, and there may be tiny red spots on the roof of the mouth. The appearance alone cannot confirm strep, so testing is needed.
Sources
This guide was written from current patient and clinical guidance, including:
- CDC: Strep Throat: All You Need to Know
- Infectious Diseases Society of America: Clinical Practice Guideline for the Diagnosis and Management of Group A Streptococcal Pharyngitis
- American Academy of Pediatrics (HealthyChildren.org): Strep Throat
- MedlinePlus: Strep throat
- American Heart Association: Prevention of Rheumatic Fever and Diagnosis and Treatment of Acute Streptococcal Pharyngitis