When is a person with strep throat no longer contagious after starting antibiotics?

From the Guidelines

A person with strep throat is typically no longer contagious after taking antibiotics for 24 hours. Once you've completed the first full day of antibiotic treatment, you generally can't spread the bacteria to others 1. However, it's crucial to complete the entire course of antibiotics as prescribed by your doctor, usually 10 days of penicillin or amoxicillin, even if symptoms improve before then. Common antibiotic prescriptions include penicillin V (250-500 mg twice daily), amoxicillin (500 mg twice daily), or azithromycin (500 mg on day 1, then 250 mg daily for 4 more days) for those with penicillin allergies. The antibiotics work by killing the Group A Streptococcus bacteria that cause the infection. While you may return to work or school after 24 hours of treatment, continuing good hygiene practices like handwashing and not sharing personal items remains important. The full antibiotic course ensures complete eradication of the bacteria, preventing complications like rheumatic fever and reducing the risk of antibiotic resistance.

Some key points to consider:

• The American Heart Association recommends that patients with strep throat take antibiotics for 10 days to prevent rheumatic fever 1.
• The Infectious Diseases Society of America also recommends a 10-day course of antibiotics for strep throat, with options including penicillin V, amoxicillin, and azithromycin 1.
• It's essential to complete the full course of antibiotics, even if symptoms improve before then, to ensure that the bacteria are fully eradicated and to reduce the risk of antibiotic resistance.
• Good hygiene practices, such as handwashing and not sharing personal items, can help prevent the spread of strep throat and other infections.

Overall, while a person with strep throat may no longer be contagious after 24 hours of antibiotic treatment, it's crucial to complete the full course of antibiotics and practice good hygiene to prevent complications and reduce the risk of antibiotic resistance.

From the FDA Drug Label

Treatment should be continued for a minimum of 48 to 72 hours beyond the time that the patient becomes asymptomatic, or evidence of bacterial eradication has been obtained

A person with strep throat is no longer contagious after being on antibiotics for at least 24 to 48 hours 2, however the provided text does not directly state this information. Key points to consider:

• The FDA drug label does not directly answer when a person with strep throat is no longer contagious after starting antibiotics.
• The provided text only mentions that treatment should be continued for a minimum of 48 to 72 hours beyond the time that the patient becomes asymptomatic, or evidence of bacterial eradication has been obtained.
• Clinical guidelines typically recommend that patients with strep throat are no longer contagious after 24 to 48 hours of antibiotic therapy, but this information is not present in the provided drug labels.

From the Research

Strep Throat Contagious Period After Antibiotic Start

• A person with strep throat is typically no longer contagious after completing a full 24 hours of antibiotics 3.
• Studies have shown that within the first 24 hours of initiating antibiotic therapy, 83% of patients become "culture negative", meaning they are no longer contagious 3.
• However, it's essential to note that some patients may still have a positive culture after 24 hours, and the risk of transmission to close contacts may persist 3.
• The type of antibiotic used can also impact the duration of contagion, with some studies suggesting that certain antibiotics like azithromycin may be less effective in eradicating the bacteria than others like penicillin V 4.
• Other factors, such as compliance with the antibiotic regimen, reexposure to infected individuals, and copathogenicity, can also influence the contagious period 5.

Antibiotic Regimens and Contagious Period

• Traditional 10-day antibiotic regimens have been compared to shorter courses, such as 5- to 7-day regimens, with some studies finding similar effectiveness and safety profiles 6.
• However, other studies have suggested that longer courses of antibiotic therapy, such as 10 days of clarithromycin, may be more effective in eradicating the bacteria than shorter courses, such as 5 days of azithromycin 7.
• The optimal antibiotic regimen and duration for treating strep throat and minimizing the contagious period are still being researched and debated 3, 4, 5, 6, 7.