no the penicillin did not cause his gums to bleed. this was just a coincidence but bleeding gums are a sign of gingivitis so it may be wise to consult his dentist.
can penicillin cause gums to bleed. my 2 yr old grandson was very ill with vomiting and with fever of 100 when taking asprin and 104 when it wore off. first dr visit they only game him medication for vomit and recommended children tylenol. we took him back after 4 days as fever continued to be high they gave him penicillin shot and now his gums are bleeding and are very tender. he crys when we try to brush his teeth.