This case was reported by a healthcare professional and described the occurrence of allergic reaction in an adult female subject who was vaccinated with ENGERIX B (GlaxoSmithKline). On 14 March 2013, the subject received unspecified dose of ENGERIX B (unknown route, injection and batch number). Less than one month after vaccination with ENGERIX B, the subject experienced allergic reaction. At the time of reporting, the outcome of the event was unspecified. Follow-up information was received on 23 May 2014 from consumer via GSK Legal Department. On 15 October 2013, the subject received 1st dose of ENGERIX B (40mcg, right deltoid) and experienced overdose. (This vaccination date conflicts with previously reported date). That same day, after receiving ENGERIX B, the subject was driving and felt the need to pull over to sleep; this was reported not normal behavior for the subject. She noticed that she had some back pain, stomach pain, felt nauseous, clammy and all around just did not feel right or like herself. The subject reported she forced herself to drink the only thing that sounded good at that time and all she felt she could handle; a milkshake. Her appetite was diminished. The next day, on 16 October 2013, she felt weak with continued back and stomach pain. She reported after work she went to bed, which again is not normal behavior for her. The weakness, stomach pain and lack of appetite continued on 17 October 2013. On 18 October 2013 she had more severe abdominal pain and went to a clinic where she had a brief physical exam with palpation on the abdomen. The subject was sent to an emergency room (ER). At the ER, the subject had a chest x-ray. Lab work revealed elevated liver enzymes. "They proceeded with a gallbladder sonogram and found it to be within normal limits and then performed an abdominal CT (computed tomography) scan which showed mesenteric adenitis and they still could not explain the severe abdominal pain I was having". The subject stated she was not a previous IV (intravenous) drug user, nor received a blood transfusion. A hepatitis panel was then performed which came back positive for Hepatitis B. The subject informed the ER physician that she had a hepatitis B vaccine on Tuesday (15 October 2013) and they stated that this would explain the elevated liver enzymes, severe abdominal pain and positive Hepatitis B results. The subject was ordered to drink plenty of water, take some pain medicine, eat bland food and get plenty of rest and have follow up Hepatitis lab done. The subject stated "I stayed in bed with a lack of appetite, weakness and abdominal pain through to Tuesday morning missing yet another day of work. I forced myself to return to work on Tuesday. On the Thursday (24 October 2013) following I developed an unexplained rash on my chest which went away within a few days". On 05 December 2013, she had follow-up labs performed and the were within normal limits. Relevant diagnostic tests included: On 10 October 2013, Hepatitis B surface antigen negative and Hepatitis B Core Antibody, total Negative. On 18 October 2013, Hepatitis B Surface antigen (Neutralization): Positive and Hepatitis B surface antigen: reactive. Abdominal x-ray impression was small density in the right upper lobe, overlying the region of the right first rib costochondral junction. Shallow obliques could provide additional information regarding the location of this lesion. Computed Tomography of abdomen and pelvis with oral and intravenous contrast had the impression of Mesenteric Adenitis. On 05 December 2013, follow-up test of Hepatitis B surface antigen was negative. At the time of this report Hepatitis B surface antigen positive and chest rash had resolved. The outcomes of the allergic reaction, overdose, greater need of sleep, abnormal behavior, back pain, stomach pain, nausea, clamminess, did not feel like oneself, decreased appetite, feeling weak, abdominal pain, elevated liver enzymes, mesenteric adenitis, inability to perform daily activities were unspecified.