You have strep throat because a bacterium called group A strep found its way into your throat, most likely through close contact with someone who was infected. It typically takes 2 to 5 days after exposure before symptoms appear, so you were probably near a contagious person earlier in the week without realizing it. Understanding exactly how this happens, and why some people get it repeatedly, can help you figure out where the infection came from and how to avoid it next time.
How the Bacteria Gets Into Your Throat
Group A strep spreads primarily through tiny respiratory droplets. When an infected person talks, coughs, or sneezes, they release droplets containing the bacteria into the air around them. You can pick up the infection by breathing those droplets in directly, or by touching a surface where droplets landed and then touching your mouth or nose. Sharing a glass, plate, or utensils with someone who’s infected is another common route.
Once the bacteria reach your throat, they latch onto the lining of your pharynx and tonsils. They form colonies on the tonsillar surface and work their way into the small folds (called crypts) in your tonsil tissue. The bacteria can even invade individual cells of the tonsil lining and survive inside them, which is part of why the infection can be stubborn and why your throat becomes so inflamed and painful so quickly.
Where You Likely Picked It Up
The most common source is another person in your daily life. Strep circulates heavily in schools, daycare centers, workplaces, and households, anywhere people spend time close together indoors. If someone in your home or office has had a sore throat recently, that’s the most probable origin.
There’s also a less obvious possibility: carriers. Between 5% and 15% of children carry group A strep in their throat or nose without any symptoms at all. These individuals can harbor the bacteria for months, sometimes without ever having been visibly sick. Carrier strains tend to be less easily transmitted than strains causing active infection, but they can still serve as a source, particularly for young children in close-contact settings. An adult in your household or a child at school could be a carrier and never know it.
Rarely, strep spreads through improperly handled food. It can also spread from infected skin sores, though this route is more associated with skin infections than throat infections.
Why It’s More Common at Certain Times
Group A strep circulates year-round, but infections peak between December and April. During these months, people spend more time indoors in close quarters, which makes transmission far easier. If you’re reading this in late winter or early spring, the timing alone puts you in the highest-risk window.
Children between the ages of 5 and 15 get strep throat more than any other group, largely because of the close contact in school environments and their still-developing immune systems. Adults absolutely get strep too, especially parents of school-age children and anyone who works with kids. If a child in your life recently had strep, that’s a strong clue about where yours came from.
Why Some People Get It Over and Over
If this isn’t your first round of strep, you’re not alone. Recurrent strep throat is a recognized pattern, and there are a few explanations for it. The most straightforward is re-exposure: you’re in regular contact with someone who carries the bacteria, whether at home or in a childcare setting. You clear your infection with antibiotics, then get re-infected from the same source.
Another possibility is that you’re a carrier yourself. After an active infection resolves, the bacteria can persist in the deep crypts of your tonsils at low levels. You feel fine, but the bacteria haven’t fully left. When your immune system dips, perhaps from another illness, stress, or lack of sleep, the bacteria can flare up again. For people with recurrent infections, doctors sometimes try a different antibiotic than the one used previously, since the approach that works for a first episode isn’t always sufficient for persistent colonization.
What Happens If You Don’t Treat It
Most sore throats are viral and resolve on their own, but strep throat specifically needs antibiotic treatment for an important reason: untreated strep can trigger complications that go well beyond a sore throat. The most concerning is rheumatic fever, an inflammatory condition that can develop 1 to 5 weeks after a group A strep infection and can damage the heart valves. It can also lead to kidney inflammation. These complications aren’t common, but they’re serious enough that treatment is standard practice once strep is confirmed.
Group A strep remains universally susceptible to penicillin, which is still the first-choice treatment. This is unusual in an era of rising antibiotic resistance. However, resistance to backup antibiotics like erythromycin and tetracycline has been climbing. In the current 2025-2026 season in England, 26% of invasive group A strep isolates showed erythromycin resistance and 48% showed tetracycline resistance, both above the ranges seen in recent years. This mostly matters if you have a penicillin allergy, since your doctor may need to be more selective about which alternative to prescribe.
How to Reduce Your Risk Next Time
Strep is hard to avoid entirely if you’re around other people, but a few practical steps lower your odds. Don’t share drinking glasses, utensils, or water bottles, especially during the winter and spring high season. Wash your hands frequently, particularly after being in crowded indoor spaces. If someone in your household has strep, keep their dishes and towels separate until they’ve been on antibiotics for at least 24 hours, which is roughly when they stop being contagious.
If you or your child keeps getting strep despite these precautions, it’s worth considering whether someone in the household is an asymptomatic carrier. A simple throat swab can identify carriers, and treating the source can break the cycle of reinfection that frustrates so many families.