The standard medicine prescribed for strep throat is amoxicillin or penicillin, taken orally for 10 days. These two antibiotics have been the first-line treatment for decades, and Group A Strep bacteria remain fully susceptible to both, with no resistance detected.
Amoxicillin and Penicillin: The First Choice
Amoxicillin is the most commonly prescribed option, especially for children, because it tastes better in liquid form and can be taken just once or twice a day. The CDC recommends a 10-day course for both adults and children. For kids, the dose is based on body weight. Adults typically take 500 mg twice daily or 1,000 mg once daily.
Penicillin V is equally effective but requires more frequent dosing. Adults usually take 500 mg twice daily or 250 mg four times daily for 10 days. Because the dosing schedule is less convenient, most prescribers default to amoxicillin unless there’s a specific reason not to.
The full 10 days matters. Strep throat symptoms often improve within two to three days of starting antibiotics, which tempts many people to stop early. Finishing the course clears the bacteria completely and reduces the risk of complications like rheumatic fever, a condition that can damage heart valves. Rheumatic fever is rare (fewer than 0.3% of untreated strep cases), but it’s entirely preventable with proper treatment.
The One-Shot Alternative
For people who are unlikely to finish a 10-day pill course, there’s a single-injection option: benzathine penicillin G, given as one shot in the muscle at the doctor’s office. This eliminates any concern about missed doses. It’s sometimes used for children or in situations where completing oral antibiotics would be difficult. The injection handles the full course of treatment in one visit.
Options If You’re Allergic to Penicillin
A penicillin allergy changes the picture. Your doctor will choose from a different class of antibiotics depending on the type and severity of your allergy. First-generation cephalosporins (like cephalexin) are often used for people whose penicillin allergy is mild, such as a rash, since cross-reactivity between the two drug classes is low.
For more serious penicillin allergies, options like azithromycin or clindamycin have historically been used. However, there’s an important caveat: about 1 in 3 invasive Group A Strep infections now involve bacteria resistant to erythromycin and clindamycin. This doesn’t affect penicillin or amoxicillin (which remain fully effective), but it means your doctor may need to think carefully about which backup antibiotic to choose if penicillin isn’t an option for you.
Pain Relief While Antibiotics Work
Antibiotics kill the bacteria, but they don’t immediately relieve the sore throat. Over-the-counter pain relievers help bridge that gap. Ibuprofen (Advil, Motrin) and acetaminophen (Tylenol) both reduce throat pain and fever effectively. You can alternate between the two if one alone isn’t enough.
One caution for parents: aspirin should not be given to children or teenagers with strep throat. It’s been linked to Reye’s syndrome, a rare but serious condition, in young people recovering from infections. Stick with ibuprofen or acetaminophen for kids.
How Quickly You’ll Feel Better
Most people notice improvement within 24 to 48 hours of their first dose. Fever usually drops first, followed by a gradual easing of throat pain. You stop being contagious about 12 hours after starting antibiotics, which is the standard threshold schools and workplaces use for return.
If your symptoms haven’t improved at all after 48 hours, or if they get worse, contact your doctor. That can signal a different infection, an antibiotic that isn’t working for your particular case, or a complication like a peritonsillar abscess. But for the vast majority of confirmed strep cases, amoxicillin or penicillin resolves the infection completely within the 10-day course.
Why Strep Needs an Antibiotic at All
Unlike most sore throats, which are caused by viruses and clear up on their own, strep throat is a bacterial infection. Antibiotics shorten the duration of symptoms, prevent you from spreading the bacteria to others, and protect against rare but serious complications. Rheumatic fever can develop two to four weeks after an untreated strep infection and cause lasting damage to the heart. Post-streptococcal kidney inflammation is another uncommon but real risk. A simple 10-day course of a cheap, widely available antibiotic eliminates these possibilities almost entirely.