How long are you contagious after starting antibiotics for pneumonia?

Not contagious: Bacterial pneumonia is not typically spread person to person so this is not an issue.

Varies: The period of contagiousness varies with the type of organism (bacteria/virus) causing the pneumonia. With antibiotic therapy, it is generally 72 hours for most common bacteria although exceptions are there. With viruses, it may be longer as your respiratory secretions may still have virus that can be transmitted to others for 7-10 days despite the use of antibiotics. Talk to your doctor.