Strep throat is contagious primarily during the period when a person is infected and symptomatic, but the exact duration depends on whether or not antibiotic treatment is used.
- Without antibiotics, a person with strep throat can be contagious for about 2 to 3 weeks (14 to 21 days), even after symptoms improve
- Once antibiotics are started, the contagiousness significantly decreases, and people typically become much less contagious within 24 to 48 hours of beginning treatment
- The incubation period (time from exposure to symptoms) is about 2 to 5 days, during which a person can also spread the bacteria
- People who do not take antibiotics remain contagious for a longer period and can spread the infection through respiratory droplets and direct contact
- Children can usually return to school after 24 hours of antibiotic treatment, as they are no longer considered contagious by then
In summary, strep throat is contagious from shortly after exposure, through the symptomatic period, and up to several weeks if untreated. Antibiotic treatment reduces contagiousness to about 24-48 hours after starting medication
