Strep throat is contagious for about 2-3 weeks in individuals that do not take antibiotics. However, individuals that take antibiotics for strep throat usually are no longer contagious about 24 hours after initiating antibiotic therapy.
The bacteria that cause strep throat can be transmitted person-to-person by direct contact, especially from mucus droplets from the mouth and indirect contact, such as kissing and sharing utensils or drinking cups.