What is strep throat?
Strep throat (streptococcal pharyngitis or tonsillitis) is an infection of the throat and tonsils by Streptococcus pyogenes, also called group A strep. It spreads by droplets from coughing and sneezing, by close contact and through shared cups, plates or cutlery. It is most common in children aged 5 to 15 and in adults in contact with children, and it peaks in winter and early spring.
It is different from the much more frequent viral sore throat of a cold, and from tonsillitis caused by other organisms. See also swollen tonsils.
Typical symptoms
- Sudden sore throat with pain on swallowing.
- Fever, often above 38 °C, with headache and tiredness.
- Red, swollen tonsils, sometimes with white or yellow patches or streaks of pus.
- Tiny red spots on the roof of the mouth (petechiae).
- Tender, swollen glands at the front of the neck.
- Stomach ache, nausea or vomiting, especially in children.
- A fine red, sandpaper-like rash (scarlet fever) in some people.
- Usually absent: cough, runny nose, hoarseness and red eyes, which point towards a virus.
Viral sore throat or strep?
The look of the throat cannot reliably separate the two. Doctors use scoring systems such as the Centor or McIsaac criteria, which give a point each for fever, tonsillar exudate, tender front neck glands and absence of cough (and add or subtract a point for age). Low scores make strep unlikely and no test is needed; higher scores prompt a rapid test or culture.
- Rapid antigen test: results in minutes; if positive, treat. In children and teenagers a negative result is usually confirmed with a culture.
- Throat culture: swab sent to the lab; results in 1–2 days.
- Do not request antibiotics without a test: most sore throats are viral, and antibiotics will not help.
Treatment
The IDSA guideline recommends antibiotics for confirmed strep. Penicillin V or amoxicillin for 10 days is first choice, with alternatives (cephalexin, azithromycin or clindamycin, depending on local resistance) for those with penicillin allergy. A single injection of benzathine penicillin is also an option. Symptoms usually start improving within 24–48 hours of starting treatment, but you should finish the course to eradicate the bacteria.
- Pain and fever: paracetamol (acetaminophen) or ibuprofen.
- Fluids and soft foods, plus saltwater gargles for older children and adults.
- Rest until the fever is gone.
- Replace the toothbrush after about 24 hours of antibiotics to avoid re-infection.
How long are you contagious?
Without treatment, you can spread strep for two to three weeks, though the greatest risk is while you are ill. After 12–24 hours on antibiotics and once the fever has gone, you are generally no longer considered contagious, and children can usually return to school the next day. Wash your hands, cover coughs and avoid sharing cups, cutlery and towels in the meantime.
Possible complications
- Peritonsillar or retropharyngeal abscess: collection of pus; requires drainage and antibiotics.
- Ear and sinus infections and swollen neck glands.
- Scarlet fever.
- Acute rheumatic fever: rare in high-income countries; it can affect the heart, joints and brain and is prevented by timely antibiotic treatment.
- Post-streptococcal glomerulonephritis: kidney inflammation that antibiotics do not prevent, but is also rare.
- Invasive strep disease (very rare): severe skin or deep infections and toxic shock.
Repeated strep throats
Some people have recurrent infections or positive swabs without symptoms (carriers), who do not usually need treatment. If you have frequent well-documented strep throats, an ENT specialist can discuss options, which may include tonsillectomy when criteria are met (for example, seven episodes in a year, five a year for two years or three a year for three years). Family members can sometimes pass the infection back and forth, so testing household contacts with symptoms is sometimes advised.
Strep throat in young children
Strep is uncommon under the age of three; sore throat in toddlers is usually viral. Older children often present with fever, stomach ache and refusal to eat. If your child has a high fever and a sore throat without cough, see a doctor for a swab. Make sure they drink enough: dehydration is the commonest reason for admission.
When to see a doctor
- Fever of 38.5 °C or more with a severe sore throat and no cough.
- White patches on the tonsils, tender neck glands, or a recent contact with strep.
- A sore throat lasting longer than a week, or getting worse after initial improvement.
- Difficulty swallowing fluids, drooling or breathing problems (urgent).
- A rash, joint pain or dark urine after a sore throat.
- Frequent sore throats or tonsil infections.
Three common situations
A 7-year-old with fever and a sore throat but no cough: likely candidate for a rapid test; get it done and treat if positive.
An adult with a mild sore throat, runny nose and cough: almost certainly viral; no test or antibiotics needed.
An adult who took antibiotics left over from a previous illness: this is not recommended; get tested and treated properly.
Key points to remember
Strep throat is common, treatable and rarely serious. Get a test when symptoms fit, take the full antibiotic course if positive, stay off school or work until fever-free and 12–24 hours into treatment, and watch for warning signs. Our ENT team can examine your throat and arrange testing.
This guide is for general information and does not replace an assessment by your own doctor or ENT specialist.
Questions about strep throat
These answers are general information and do not replace an examination or individual medical advice.
Can strep throat go away on its own?
It usually improves in about a week without treatment, but antibiotics shorten the illness, reduce contagion and prevent rare complications.
How do I know if it is strep or a cold?
Strep brings sudden severe sore throat with fever and often no cough or runny nose; a cold typically comes with cough and congestion. Only a test can confirm it.
How long should I take antibiotics for strep?
Usually 10 days of penicillin or amoxicillin, even if you feel better after two or three days.
When can my child return to school?
Usually 12–24 hours after starting antibiotics and when the fever has gone.
Is strep throat dangerous?
Rarely, but untreated infection can lead to abscesses or rheumatic fever. That is why treatment is advised.
Can adults get strep throat?
Yes, though it is less common than in children: about 5–15% of adult sore throats.
Sources
- CDC · Strep throat: all you need to know
- CDC · Antibiotic use for sore throat and strep
- IDSA · Clinical practice guideline for group A streptococcal pharyngitis (2012)
- NHS · Sore throat
This guide is for general information and does not replace medical advice. How a problem is diagnosed and treated depends on your examination and medical history. If you think you have an emergency, contact your local emergency services.