Strep throat is treated with antibiotics, and the go-to choices are penicillin or amoxicillin. These have been the standard for decades because the bacteria that cause strep (Group A Streptococcus) have never developed resistance to them. Most people take a 10-day course, start feeling better within a day or two, and become non-contagious within 12 hours of their first dose.
First-Line Antibiotics
Penicillin and amoxicillin are prescribed first for nearly every strep throat case. Amoxicillin is more commonly given to children because it tastes better in liquid form and can be taken once daily. Both require a full 10-day course to fully clear the infection and prevent complications, even though symptoms usually improve much sooner. Stopping early is one of the most common mistakes, and it raises the risk of the infection returning or causing problems down the line.
For people who have trouble remembering daily pills for 10 days, a single injection of penicillin is another option. It delivers the full treatment in one visit, which can be especially practical for kids or anyone with a history of not finishing antibiotic courses.
If You’re Allergic to Penicillin
Several alternatives exist if you can’t take penicillin or amoxicillin. The right choice depends on the type of allergy you have.
If your reaction to penicillin was mild (a rash, for example, rather than throat swelling or difficulty breathing), certain cephalosporin antibiotics like cephalexin or cefadroxil are safe options. Both are taken for 10 days. These are closely related to penicillin, though, so they’re off the table if you’ve ever had a severe allergic reaction.
For true severe penicillin allergies, the main alternatives are:
- Azithromycin: A 5-day course, which is shorter and more convenient than most options. However, resistance is a growing concern. Among invasive Group A Strep samples tested by the CDC in 2023, 27% were resistant to this class of antibiotic, meaning it simply won’t work for a significant number of infections.
- Clarithromycin: Taken twice daily for 10 days. It belongs to the same drug class as azithromycin, so the same resistance concerns apply.
- Clindamycin: Taken three times daily for 10 days. Resistance rates are similar to azithromycin (around 26% in 2023 CDC data), but it remains an option when other choices aren’t suitable.
Because of these rising resistance rates, your doctor may choose one alternative over another based on what’s circulating in your area. If you’ve been prescribed azithromycin and your symptoms aren’t improving after two or three days, that’s worth a follow-up call.
Getting the Right Diagnosis First
Antibiotics only work on bacterial infections, and strep throat can look a lot like a viral sore throat. Doctors use a set of clinical signs, sometimes called the Centor criteria, to decide whether testing is warranted. These include fever, swollen lymph nodes in the neck, white patches on the tonsils, and the absence of a cough. No single symptom confirms strep on its own, and the score itself isn’t enough to diagnose it. A rapid strep test or throat culture is still needed before antibiotics are prescribed.
This matters because taking antibiotics unnecessarily contributes to resistance and exposes you to side effects for no benefit. If your rapid test is negative but your doctor still suspects strep, a throat culture (which takes a day or two) can catch cases the rapid test misses.
Managing Pain and Fever While Antibiotics Work
Antibiotics kill the bacteria, but they don’t do much for the immediate pain. Over-the-counter pain relievers are the main tool for feeling better in the first couple of days. Ibuprofen (Advil, Motrin) and acetaminophen (Tylenol) both reduce fever and ease throat pain. You can alternate between the two if one alone isn’t enough. Aspirin should not be given to children or teenagers due to the risk of a rare but serious condition called Reye’s syndrome.
Beyond medication, practical measures help: drinking plenty of fluids, eating soft foods, and resting. Warm broth, cold popsicles, and throat lozenges (for older kids and adults) can all take the edge off. Strep throat pain tends to peak in the first 48 hours and then steadily improves once antibiotics take hold.
For severe throat pain and swelling, some doctors prescribe a single dose of a corticosteroid like dexamethasone. A systematic review published in The BMJ found that a single oral dose (10 mg for adults) added to standard care helped reduce pain faster in emergency and primary care settings. This isn’t routine for every strep case, but it’s sometimes used when swallowing is extremely difficult.
Why Finishing the Full Course Matters
Strep throat usually feels dramatically better within two to three days of starting antibiotics, which tempts many people to stop taking them. The full 10-day course (or 5 days for azithromycin) is designed to completely eliminate the bacteria, not just suppress symptoms. Stopping early can allow surviving bacteria to rebound, leading to a second round of illness that may be harder to treat.
More importantly, untreated or undertreated strep can lead to complications. Rheumatic fever, which can damage the heart valves, is the most well-known risk. Kidney inflammation is another possibility. These complications are rare in countries where antibiotics are readily available, precisely because most people complete treatment. Starting antibiotics within the first 9 days of symptoms is generally considered sufficient to prevent rheumatic fever.
When Strep Keeps Coming Back
Some people, especially school-age children, get strep throat multiple times in a year. When strep returns shortly after finishing a course of antibiotics, doctors typically switch to a different antibiotic class rather than repeating the same one. A cephalosporin, clindamycin, or amoxicillin combined with a compound that helps it work against resistant bacteria are all common second-round choices.
Recurrent strep can also sometimes mean you’re a carrier. Strep carriers harbor the bacteria in their throat without being sick, then catch a viral sore throat that gets mistakenly attributed to strep. Sorting this out usually requires a throat culture when you’re feeling well. If tonsillectomy is ever discussed, it’s typically reserved for cases with seven or more documented infections in a single year, or five per year over two consecutive years.
Protecting Your Gut During Treatment
A 10-day course of antibiotics can disrupt the balance of bacteria in your digestive system, sometimes causing diarrhea, nausea, or stomach discomfort. Some doctors suggest increasing your intake of probiotic-rich foods like yogurt or kefir during or after treatment. The evidence that probiotic supplements specifically prevent antibiotic-associated side effects isn’t definitive yet, according to Harvard Health Publishing, but eating fermented foods is low-risk and may help. Depending on the antibiotic, it may be more effective to focus on probiotics after finishing the course rather than during it.
Contagion and Returning to Normal
You stop being contagious within 12 hours of your first antibiotic dose. Most schools and workplaces follow this same guideline: you can return after 12 hours on antibiotics, as long as your fever has broken and you feel well enough. Without antibiotics, strep remains contagious for two to three weeks, even as symptoms fade. This is one of the practical reasons treatment matters beyond just feeling better faster.