Strep throat is a bacterial infection that causes severe soreness and swelling in the throat and tonsils. It’s caused by a bacterium called group A Streptococcus, which spreads through respiratory droplets and direct contact with an infected person’s saliva or nasal secretions. Unlike most sore throats, which are caused by viruses and clear up on their own, strep throat requires antibiotics to heal properly and prevent complications.
Strep throat is most common in children between ages 5 and 15, but anyone can get it. It tends to circulate in places where people are in close contact, like schools, daycare centers, and households.
How Strep Throat Differs From a Viral Sore Throat
Most sore throats are caused by viruses, not bacteria, and the distinction matters because the treatment is completely different. A few signs point toward a virus rather than strep: a cough, runny nose, hoarseness, or pink eye. If you have those symptoms alongside a sore throat, you’re more likely dealing with a cold or another viral infection.
Strep throat, on the other hand, tends to come on fast. The pain is often intense and makes swallowing difficult. You may notice red, swollen tonsils with white patches or streaks of pus, tiny red spots on the roof of your mouth, swollen lymph nodes in the front of your neck, and a fever. Some people, especially children, also experience headache, stomach pain, nausea, or a sandpaper-like rash (which is called scarlet fever when it accompanies strep). Notably, strep throat usually does not come with a cough or congestion.
How It Spreads
The bacteria travel primarily through respiratory droplets when an infected person coughs, sneezes, or talks. You can also pick it up by touching a surface contaminated with those droplets and then touching your mouth or nose, or by sharing utensils, cups, or food with someone who’s infected. Close, prolonged contact is the biggest risk factor, which is why strep outbreaks frequently move through families and classrooms.
A person with untreated strep throat can be contagious for weeks. Once antibiotics are started, that window shrinks dramatically. Most people are no longer contagious within 12 hours of their first dose.
Getting Tested
Because strep throat and viral sore throats can look similar, a test is the only reliable way to confirm the diagnosis. The most common option is a rapid antigen test, sometimes called a rapid strep test. A healthcare provider swabs the back of your throat, and results come back in minutes. These rapid tests are highly accurate at confirming strep when it’s present, with a specificity of about 96%, meaning false positives are rare.
If the rapid test comes back negative but your provider still suspects strep, they may send a throat culture to a lab. This takes one to two days but can catch infections the rapid test misses.
Treatment With Antibiotics
Penicillin or amoxicillin is the standard treatment for strep throat. The typical course lasts 10 days. For people with a penicillin allergy, other antibiotics are available as alternatives.
It’s important to finish the entire course of antibiotics even if you start feeling better after a few days. Stopping early can allow the bacteria to survive and increases the risk of complications. Most people notice significant improvement within 48 hours of starting treatment, and as mentioned, you’re generally no longer contagious after 12 hours on antibiotics. Schools and daycares typically require children to stay home until that 12-hour mark has passed.
Managing Pain at Home
Antibiotics kill the bacteria, but they don’t provide instant pain relief. Over-the-counter pain relievers like ibuprofen (Advil, Motrin) or acetaminophen (Tylenol) can help reduce throat pain and bring down a fever. Avoid giving aspirin to children or teenagers, as it has been linked to Reye’s syndrome, a rare but serious condition.
Several simple remedies can ease discomfort while you recover:
- Salt water gargle: Mix 1/4 teaspoon of table salt in 8 ounces of warm water and gargle several times a day. This works well for older children and adults.
- Cold foods: Sherbet, frozen yogurt, and frozen fruit pops can soothe an inflamed throat.
- Honey: A spoonful can coat and calm a raw throat (but not for children under one year old).
- Rest: Sleep gives your immune system the energy it needs to fight infection alongside the antibiotics.
Spicy foods and acidic drinks like orange juice tend to irritate an already raw throat, so it helps to avoid those until you’re feeling better.
What Happens if Strep Goes Untreated
Left untreated, strep throat can lead to serious complications. The two most significant are rheumatic fever and a kidney condition called post-streptococcal glomerulonephritis (PSGN).
Rheumatic fever is an inflammatory condition that can damage the heart valves, joints, and nervous system. It typically develops a few weeks after an untreated strep infection and is the primary reason antibiotics are so strongly recommended for confirmed strep. While rheumatic fever has become less common in developed countries, it still occurs and can cause lasting heart damage.
PSGN affects the kidneys and can develop after strep throat, scarlet fever, or a strep skin infection. It’s more common in children than adults. Most people recover within a few weeks, but in rare cases, particularly in adults, it can lead to long-term kidney problems. Symptoms include dark or cola-colored urine, swelling in the face and hands, and reduced urine output.
Untreated strep can also lead to a peritonsillar abscess, which is a painful collection of pus near the tonsils, or spread to the sinuses and ears.
Strep and Sudden Behavioral Changes in Children
In rare cases, a strep infection can trigger a condition called PANDAS (Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections). This happens when the immune system, while fighting the strep bacteria, mistakenly attacks healthy tissue in the brain. The result is a sudden, dramatic onset of obsessive-compulsive behaviors, tics, or both, typically within three months of the strep infection.
PANDAS is diagnosed based on the combination of sudden-onset OCD or tics and evidence of a recent strep infection, such as a positive throat culture. Treatment focuses on clearing the strep infection with antibiotics, which often reduces the neuropsychiatric symptoms as well. Researchers at the National Institute of Mental Health have explored whether long-term antibiotics could prevent recurrences, but there isn’t enough evidence yet to support that approach.
If your child develops unexpected behavioral changes like severe anxiety, new tics, or obsessive behaviors shortly after a sore throat, a strep test is worth requesting.