###Human: My 13 year old nephew sometimes becomes so angry and beats his younger brother and sometimes when things not given to him he becomes angry and tells he wants to go out of the house. ###Assistant: Hi. I would have answered the query more appropriately if you had included a little more information regarding his day to day activities, his academic performance, his peer relationship, etc. Anyways, regarding your query, it can be due to sibling rivalry, or it could be due to adjustment problems or even due to any diagnosable childhood psychiatric problem. If the above problems are just a part of growing up, then psychotherapeutic sessions might be helpful for your nephew. But if these symptoms are due to any underlying psychiatric illness, he might need a psychiatric consultation. About the medicines, the increase in temperature due to medicine is quite unlikely. But yes, it can cause heaviness in the head, which can be perceived as something happening in the head.