Antibiotics often begin working soon after the first doses, and many people notice their symptoms easing within about two to three days. The full course is still needed to clear the infection properly even when you feel better quickly.
The timing varies with the type and severity of infection. Some, like uncomplicated bladder infections, may improve fast, while skin or bone infections can take longer.
If you are not improving after two to three days, or you are getting worse, develop a high fever, spreading redness, or feel very unwell, contact your prescriber or seek urgent care, as the antibiotic choice may need to change or you may need further assessment.