Inclusion Criteria:  Inclusion Criteria for screening  Patients 3-18 years old admitted at our institution with penicillin allergy label in electronic medical record Patients with available parent/s or legal guardian who can give both written and verbal consent to the oral challenge testing Patients with available parent/s or legal guardian during the conduct of oral amoxicillin challenge testing  Inclusion Criteria for oral challenge test  - Patients who will be identified as low-risk patients based on the standardized screening questionnaire. Low-risk group patients are those patients with previous reaction not suggestive of anaphylaxis AND not requiring hospitalization for the reaction OR reaction considered non-immunologic (e.g. diarrhea, nausea, yeast vaginitis) OR exposure to penicillin-containing antibiotic after the date of reported reaction with no anaphylaxis and hospitalization AND no serious types of delayed reactions such as Steven-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), acute interstitial nephritis (AIN), drug-induced hepatitis or other documented organ injury, drug rash eosinophilia systemic symptoms (DRESS), hemolytic anemia, drug-induced cytopenia, and serum sickness. - ---- Patients who had delayed reaction (onset more than 24 hours) of isolated, non-progressive symptoms (such as rash/hives alone) also belong to this group.  Exclusion Criteria:  Exclusion Criteria for screening  Patients who cannot tolerate amoxicillin/penicillin by enteral route. Patients with no parents or legal guardian available to give both written and verbal consent to the oral challenge testing Patients with no available parents or legal guardian during the conduct of oral amoxicillin challenge testing Patients currently on antihistamine or have received antihistamine in the previous 48 hours Patients who are critically ill Patients who have been vomiting more than twice in the past 24 hours or are actively vomiting Patients with respiratory symptoms warranting oxygen therapy or pulmonary finding of wheezing or stridor Patients identified as having anaphylactic reaction to penicillin in the electronic medical record  Exclusion Criteria for oral challenge testing  Patients who will be identified as no-risk patients based on the standardized screening questionnaire. No-risk group patients are those patients who are historically labeled with penicillin allergy in the EMR based on family history alone OR those who have tolerated penicillin after a concerning incident without any reaction OR with penicillin allergy label but deny any history of reaction to any form of penicillin on screening questionnaire Patients who will be identified as high-risk patients based on the standardized screening questionnaire. High-risk group patients are those patients with penicillin allergy label on EMR with previous reaction suggestive of anaphylaxis OR requiring hospitalization/epinephrine administration for the reaction OR reactions considered immunologic (angioedema, joint pains) OR involving serious types of reactions such as Steven-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), acute interstitial nephritis (AIN), drug-induced hepatitis or other documented organ injury, drug rash eosinophilia systemic symptoms (DRESS), hemolytic anemia, drug-induced cytopenia, and serum sickness. Patients who were previously diagnosed with penicillin allergy by an allergist also belong to the high-risk group.