When a person is "infectious", it means they're able to pass their infection on to others.
You're usually no longer infectious 24 hours after starting a course of antibiotics, although this time period can sometimes vary.
For example, the antibiotics may take longer to work if your body takes longer to absorb them or if you're taking other medication that interacts with the antibiotics.
Talk to your pharmacist or GP if you have any questions or concerns about your course of antibiotics.
It's important to finish your course of antibiotics, even if you're no longer infectious and feeling better.
Failing to finish the course may result in the infection returning.