Get urgent help for breathing or deep-neck warning signs
Use emergency care for difficulty breathing, noisy breathing, blue or grey colour, severe drowsiness or confusion, or inability to swallow saliva. Seek same-day urgent assessment for drooling, a muffled “hot potato” voice, inability to open the mouth normally, marked one-sided throat swelling, neck swelling or stiffness, dehydration, a rapidly spreading rash, severe systemic illness, or worsening after initial improvement. These can indicate an abscess, airway problem, sepsis, or another diagnosis.
Strep throat is an infection of the throat and tonsils caused by group A Streptococcus bacteria. Most sore throats are viral, and symptoms overlap. When clear viral features are absent, examination alone cannot reliably separate strep from viral pharyngitis; a rapid test or throat culture may be needed. Confirmed strep is treated to shorten illness, reduce spread, and prevent complications.
Key points
- Group A strep causes about 20%–30% of sore throats in children and 5%–15% in adults, according to CDC estimates.
- Cough, runny nose, hoarseness, conjunctivitis, or mouth ulcers point more strongly toward a virus.
- White patches and fever can occur with strep but do not prove it.
- Rapid tests are specific but can miss cases; follow-up after a negative result differs by age and local guidance.
- Do not take leftover antibiotics or share a household member’s prescription.
What causes strep throat?
Group A strep bacteria can live in the nose and throat and spread through respiratory droplets and direct contact. People may become infected after close contact at home, school, childcare, dormitories, military settings, or other crowded environments. Sharing unwashed utensils or touching secretions can also spread the bacteria.
The same organism can cause scarlet fever, impetigo, cellulitis, and rarer invasive infections. “Strep” is not one universal illness, and a skin infection does not mean someone has strep throat. This page addresses acute pharyngitis.
School-aged children are affected most often. Classic strep throat is uncommon under age three, where group A strep may produce a different pattern. Clinicians interpret symptoms and testing differently by age and local rheumatic-fever risk.
Symptoms that can occur with strep
Typical features include a sudden sore throat, pain when swallowing, fever, red and swollen tonsils, tender lymph nodes at the front of the neck, small red spots on the palate, and sometimes tonsillar exudate or white patches. Children may also have headache, abdominal pain, nausea, or vomiting.
Scarlet fever adds a fine, rough-textured red rash that often begins on the trunk or in skin folds, a flushed face with paler skin around the mouth, and sometimes a “strawberry” tongue. A clinician should assess a compatible rash because viral rashes, medicine reactions, and other illnesses can look similar.
Cough, runny nose, hoarseness, conjunctivitis, and oral ulcers suggest a viral cause. However, mixed or atypical presentations occur. The absence of cough increases the probability of strep but is not proof.
Other causes of a severe sore throat
Cold and influenza viruses, COVID-19, adenovirus, and mononucleosis are common alternatives. Mononucleosis may cause prolonged fatigue, prominent lymph nodes, and enlarged tonsils. Gonorrhea can infect the throat after exposure. Diphtheria is rare where vaccination is high but is a public-health emergency. Acid reflux, smoke, dryness, allergy, and voice strain can cause non-infectious throat symptoms.
A peritonsillar abscess often causes severe one-sided pain, muffled voice, drooling, difficulty opening the mouth, and displacement of the uvula. Retropharyngeal infection can cause neck stiffness, drooling, and breathing problems, especially in children. Lemierre syndrome is a rare, serious complication involving infection and a neck vein clot. Red flags require urgent care, not an online score.
Clinical scores estimate risk, not diagnosis
FeverPAIN and Centor-type scores combine features such as fever, tonsillar findings, tender neck nodes, absence of cough, and symptom timing or age. The 2025 IDSA update supports a clinical scoring system as part of risk assessment rather than unaided judgement.
A low score can help identify people unlikely to benefit from testing or antibiotics in some health systems. A higher score may support testing or a prescribing strategy according to local guidance. The score does not see the airway, identify an abscess, detect a viral feature outside the checklist, or account for all medical risks.
Rapid test or throat culture?
A rapid antigen detection test uses a throat swab and can provide a result during the visit. It has high specificity, so a positive result in a person with compatible symptoms usually confirms group A strep. Sensitivity varies, which means a negative rapid test can miss some infections.
Throat culture takes longer but remains the reference standard in CDC guidance. In symptomatic children older than three, CDC recommends a culture after a negative rapid antigen test, with a system to contact the family and begin treatment if it becomes positive. This reduces the risk of missing infections associated with acute rheumatic fever.
For adults and other ages, a backup culture after a negative rapid test is not routinely required in the US pathway because acute rheumatic fever is rare. Other countries use different test availability, scoring thresholds, and delayed-prescription pathways. Follow the local clinician’s plan.
Modern molecular tests may have different accuracy and turnaround. Ask what test was used and whether a negative result needs confirmation rather than treating all “rapid strep” tests as identical.
A positive test can sometimes reflect carriage
Some healthy people carry group A strep in the throat without illness. If a carrier develops a viral sore throat, a strep test can be positive even though the virus is causing the symptoms. This is one reason clinicians avoid testing people with clear viral features or no symptoms.
Carriage is more common in children and during high-transmission seasons. Repeated positive tests need review of symptoms, exposure, previous treatment, and complications. Routine testing or treatment of symptom-free household contacts is generally not needed unless a clinician or public-health team identifies a special situation.
Treatment basics
Confirmed group A strep pharyngitis is treated with a guideline-recommended antibiotic. Benefits include modestly shorter symptoms, reduced transmission, and lower risk of complications. Choice and duration depend on age, allergy history, pregnancy, kidney or liver function, medicine interactions, local resistance, and national guidance.
This page does not name a regimen or dose. Take the prescribed medicine exactly as directed. Do not stop early, extend the course, or switch because another family member received something different. Contact the prescriber if the test result changes, symptoms worsen, a dose is missed, or side effects occur.
A recorded “penicillin allergy” should include what happened and when. Nausea or diarrhea is not the same as immediate allergy. Hives, facial swelling, wheeze, throat tightness, or collapse requires urgent care; breathing difficulty or collapse is an emergency. Severe or persistent diarrhea during or after antibiotics also needs clinical review because of C. diff risk.
What if testing is negative or antibiotics are not advised?
Most acute sore throats improve in about a week. Rest, adequate fluids, and pain or fever treatment that is safe for the person can help. A pharmacist can check options around pregnancy, age, kidney disease, ulcers, blood thinners, and other medicines. Medicated lozenges provide only a small average reduction in pain.
A delayed prescription is used in some systems when the probability is intermediate and immediate treatment is not required. It should include clear instructions on when to use it, when not to, and when to seek reassessment. It is not appropriate for airway compromise, abscess signs, severe systemic illness, or high complication risk.
Contagiousness and return to school or work
Group A strep spreads through close contact and droplets. Cover coughs, wash hands, avoid sharing cups and utensils, and clean commonly touched surfaces. Washed dishes and utensils are safe to reuse.
CDC advises that people with strep throat stay home until they no longer have a fever and have taken an appropriate antibiotic for at least 12–24 hours. Schools, workplaces, healthcare roles, and local public-health authorities may set different requirements. Feeling better does not replace the minimum infection-control period.
Complications and follow-up
Local suppurative complications include abscesses around or behind the throat and infected neck lymph nodes. Acute rheumatic fever is an inflammatory disease that can affect the heart, joints, skin, or brain after group A strep infection. It is uncommon in many high-income adult populations but remains important globally and in children.
Post-streptococcal kidney inflammation can cause dark or tea-coloured urine, swelling, reduced urine, or high blood pressure. Rare invasive group A strep infection can progress rapidly with severe pain, fever, low blood pressure, or tissue damage.
Arrange review if fever or pain is worsening, hydration is difficult, a new rash develops, symptoms are not improving as expected, or they return soon after treatment. Use urgent care for the red flags at the top of the page.
Questions people often ask
Do white spots mean strep throat?
No. Strep can cause exudate, but viral infections and other conditions can too. Testing may be needed when the clinical pattern fits.
Can I have strep without fever?
Yes. Fever raises probability but is not required. Symptoms, age, examination, and testing are considered together.
Why did the clinician not test my obvious cold?
When cough, runny nose, hoarseness, conjunctivitis, or mouth ulcers clearly indicate viral pharyngitis, CDC guidance says strep testing is unnecessary.
Can strep throat go away on its own?
Symptoms may resolve, but confirmed group A strep is treated because antibiotics reduce transmission and complications. Do not use symptom improvement alone to override a test-based plan.
Sources and evidence scope
This guide was researched using current CDC guidance on group A streptococcal pharyngitis and group A strep infection, the 2025 IDSA guideline update on risk assessment, NICE guideline NG84 on acute sore throat, and CDC antibiotic-use guidance. Sources were checked on August 21, 2026. Testing, treatment, rheumatic-fever risk, school exclusion, and prescribing pathways vary by country.