Strep throat is treated with antibiotics, and the go-to choices are penicillin and amoxicillin. These have been the standard for decades because the bacteria that cause strep throat (Group A Streptococcus) have never developed resistance to them. A full course typically lasts 10 days, and most people start feeling better within a day or two of their first dose.
How Strep Throat Is Confirmed Before Prescribing
Antibiotics aren’t prescribed based on symptoms alone. A sore throat with fever and swollen glands could be viral, and antibiotics won’t help a virus. Your provider needs a positive test result before writing a prescription, either from a rapid strep test (the quick throat swab with results in minutes) or a throat culture, which is the gold standard but takes a day or two to come back.
If the rapid test comes back negative, the next step depends on your age. For children over 3, a backup throat culture is recommended because the rapid test can miss some cases. For teens and adults, a negative rapid test is usually considered reliable enough on its own, partly because the most serious complication of untreated strep, rheumatic fever, is very rare in older age groups.
First-Choice Antibiotics
Penicillin and amoxicillin are the first-line treatments for strep throat. Amoxicillin is often preferred for children simply because it tastes better in liquid form and can be taken once daily. Both are taken for 10 days. Adults are typically prescribed penicillin two to three times daily or amoxicillin once or twice daily.
It’s important to finish the entire 10-day course even though you’ll feel significantly better long before that. Stopping early doesn’t just risk a relapse. It also leaves you vulnerable to complications like rheumatic fever, which can damage heart valves. Fewer than 0.3% of people with strep throat develop rheumatic fever, but the risk drops to essentially zero with a completed antibiotic course.
Options If You’re Allergic to Penicillin
If you have a penicillin allergy, the alternative depends on the type of reaction you’ve had. For people whose allergy doesn’t involve a severe immediate reaction (like anaphylaxis or hives), a first-generation cephalosporin such as cephalexin is the usual substitute. It’s taken twice daily for 10 days and works well against strep bacteria.
For people with a history of severe allergic reactions to penicillin, cephalosporins are off the table too because the drug families are related. In those cases, providers may turn to erythromycin, also given for 10 days. Azithromycin (the well-known “Z-pack”) is FDA-approved for strep but is not a first-line recommendation, and for good reason: resistance is a growing problem. Among invasive Group A Strep samples tested by the CDC in 2023, 27% were resistant to macrolide antibiotics like azithromycin. That means in roughly one out of four cases, azithromycin may not work at all.
When You Stop Being Contagious
You’re no longer contagious within 12 hours of taking your first dose of antibiotics. That’s the standard cutoff used by schools and daycares for allowing kids to return. Before antibiotics, strep can spread through coughs, sneezes, and shared drinks for as long as symptoms last, and sometimes even before symptoms appear.
Managing Pain While Antibiotics Work
Antibiotics kill the bacteria, but they don’t do much for the raw, burning throat pain in the first day or two. Over-the-counter pain relievers are the primary recommendation for comfort. Ibuprofen (Advil, Motrin) both reduces pain and brings down fever. Acetaminophen (Tylenol) is another solid option. Aspirin should not be given to children or teenagers because of its link to Reye’s syndrome, a rare but serious condition.
Beyond pills, the basics help: rest, plenty of fluids, and soft foods that won’t scrape an inflamed throat. Warm broth, cold popsicles, and smoothies are all easier to get down than solid meals.
For particularly severe cases where the throat pain is intense and swallowing is difficult, some providers prescribe a single dose of a corticosteroid alongside antibiotics. Research published in The BMJ found that a single steroid dose tripled the likelihood of complete pain relief within 24 hours and reduced the time to first feeling better by more than 6 hours. This isn’t standard for every strep case, but it’s a tool providers use when pain is especially debilitating.
What Happens If Strep Goes Untreated
Most strep throat infections would eventually clear on their own, but “eventually” comes with risks. Without antibiotics, the infection can spread to nearby tissue, causing a peritonsillar abscess (a painful pocket of pus behind the tonsils) or sinus and ear infections. The more serious concern is rheumatic fever, an inflammatory condition that can develop one to five weeks after an untreated strep infection. It targets the heart, joints, and nervous system, and the heart valve damage it causes can be permanent.
Another possible complication is post-streptococcal kidney inflammation, which typically shows up a week or two after infection with dark or decreased urine and swelling. Both of these complications are uncommon in countries where antibiotics are readily available, but they’re the reason strep throat is one of the few sore throats that genuinely needs antibiotic treatment.