tiredness; weakness; head is burning; fatigue; drooling; hives; itching; redness; gained weight since the vaccine; This is a spontaneous report from a contactable consumer (patient's mother). A 12-years-old male patient received bnt162b2 (PFIZER-BIONTECH COVID-19 VACCINE, formulation: Solution for injection, Lot Number: ER8729; Expiration Date: 31Jul2021) via an unspecified route of administration, in left arm on 27May2021 (at the age of 12-years-old) as dose 1, single for covid-19 immunisation. Medical history included patient had an allergic reaction to penicillin before. The patient's concomitant medications were not reported. The patient had a meningitis vaccine a month before the covid vaccine. Patient's mother was calling on behalf of her 12 year old son. She stated her son received the first dose of the Pfizer COVID vaccine on 27May2021. On 27May2021,6 hours after receiving the vaccine the patient said he was very itchy and had hives on the left side of his chest. At first she thought the patient had poison ivy because it was like 3-4 inches across. The next day the patient said he was itchy when he sat up and it went up onto his neck and cheeks and that's when she realized it was hives. She called the doctor, applied cold compresses to the patient and gave him Benadryl. The hives resolved very quickly, the patient has never had hives or an allergic reaction before. By 2:30 the patient had the Benadryl and you couldn't see the red anymore. The patient could sit up but kept saying it itched and that went on for about 48 hours. You would have to look pretty closely to see the bumps. One week after the patient received the vaccine he was really weak and tired (on 03Jun2021). She stated her son also keeps having episodes of tiredness and weakness. It felt like the patient had been exercising and his legs were tired and his head felt like it was burning (on 03Jun2021). The patient's temperature was 97.7. The patient laid down and he slept pretty hard, and was drooling, for a couple of hours. When the patient woke up he didn't know where he was, the time or date and within a couple of hours the patient was fine. She didn't think anything of it the first time it happened. This event happened again 2 weeks after the vaccine. The doctor said they symptoms sound like mono but the patient's lymph nodes aren't swollen and he doesn't have a sore throat. The doctor thought the patient was having a delayed immune response to the vaccine because of the timing of it. The doctor said that by 3 weeks this should have resolved. The patient has had 2 mild episodes of this since, but he didn't go to sleep he just laid down. The doctor said to wait to get the second dose, so now it is 4 weeks since the first vaccine. The patient was at the 30th percentile for his height and average for his weight. The patient had gained weight since the vaccine but his mother didn't know if that was related to the vaccine. She was afraid of the patient having myocarditis with the second dose. The patient went to sleep after taking the Benadryl last time and she was afraid that the patient won't be able to tell her if he was having chest pain or problems breathing. She stated if his reaction was just hives she would give him Benadryl but with the risk of myocarditis after being given Benadryl he wouldn't be alert enough to tell her if something was going on with his heart due to him having fatigue as well already. The redness went away within 24 hours and the itching was gone in 48-72 hours. The redness was gone the evening of the 28th. The patient could still see and feel the bumps, the bumps were just white. The patient's head was burning happened the first 2 times he had these events. The patient's temperature was 97.7 and 98.1 fahrenheit when this happened. The other two times the patient said his head burned between his eyes and not like a headache. The doctor said that if the fatigue symptom continued he would recommend doing some blood work but since it has gotten better his mother may take him to an allergist. She thinks that the patient may be allergic to something in the vaccine. she was thinking of taking him to an allergist to see if he was allergic to one of the ingredients in the vaccine. She stated from the list of the ingredients the only ingredient she found that could be linked to the vaccine that could cause an allergic reaction would be PEG. She stated her son never had any allergies to medications or vaccines in the past. She stated she was not sure what advice should be given regarding her son receiving the second dose of the vaccine due to him having an allergic reaction to the first dose and tiredness and weakness. She stated she was not sure of the risks of vaccine versus him not being vaccinated. She would like to know if he should receive the second dose after experiencing side effects with the first dose. Reporter seriousness events was unspecified. Outcome of the events hives and itching recovered on May 2021, redness recovered on 28May2021, event tiredness and weakness was recovering and for other events was unknown.