most bronchitis is due to viruses so antibiotics are not usually indicated. respiratory viruses are contagious a day before you know you are sick to several days later. there are no viruses that just cause bronchitis so exposure to someone with bronchitis does not mean the exposed person will also get bronchitis. they may get a simple cold. or nothing at all. if your medical provider put you on an antibiotic then it is possible that he/she felt that you may have a bacterial component. since there are many different bacteria capable of being involved in bronchitis there is really no way for me to know exactly what your medical provider is treating.
if on medication after how long is bronchitis no longer contagious?