 [ Symptoms ] 13 days ago had unprotected sex 3 days later saw scab on penis fell off now its just red but healing std or a scab  13 days ago i had unprotected sex 3 days later i a saw scab on penis the scab fell off now its just red but healing it never itched much or hurt but i went and got tested yesterday and i got the results for syphilis which were negative but i do not get the results for herpes until monday but im going to be with another girl friday night and i need to know if its good to go im also worried about a false negative because i only waited 12 days to get tested any opinions [ Disease ] hi strawdine hi this info is from webmd common allergic reactions to penicillin include rashes hives itchy eyes and swollen lips tongue or face in rare cases an allergy to penicillin can cause an anaphylactic reaction which can be deadly this type of reaction usually happens within an hour after you take penicillin symptoms include difficulty breathing hives wheezing dizziness loss of consciousness rapid or weak pulses skin turning blue diarrhea nausea and vomiting if you think you are having an anaphylactic reaction call 911 immediately now as you can read it is a very rare reaction and her question was probabley 24 hours later way past what you had good luck