How long does the painful throat last in strep throat?

Few days. If you are taking antibiotics it should be much better in 48 to 72 hours. If you are not much better in 5 days return to your doc.
Pain versus illness. The pain from strep infection can vary from severe to minimal. The duration of pain varies from individual to individual. Untreated the infection can last 1-2 weeks, treated 48-72 hours. The pain resolves at a different rate than the actual infection, usually 48 hours.