Tested positive for strep throat. Taking 500 Mg penicillin vk for 24 hrs. Throat still hurting and still feel bad. How long should it take to work?

48-72 hours. Many people begin to feel relief from Strep throat symptoms after 24 hours of appropriate antibiotic therapy, but one wouldn't necessarily consider your regiment a treatment failure until you have been taking it for at least 2-3 days. Best wishes.