not long; less than a day before all traces of amoxicillin are gone so there are not post-treatment protective effects. your son is susceptible to getting strep again i hope that you were both properly lab-tested to confirm strep.
if my son finished his treatment for strep and i was diagnosed the next day is he susceptible to it? . my 2 year old son finished his amoxicillin treatment on tuesday and i was diagnosed with strep throat on wednesday. how long does the amoxicillin stay in a persons system?