A fever is a sign that the body is trying to fight the infection or sickness. Tylenol and Advil only interfere with the bodies natural ability to fight. People give these chemicals (which they are) to their children and expect them to get better, but that is not how it works. You need to support the body naturally to help get over the sickness. Lemon, vitamin C, D, etc. and echinacea for starters.
Tylenol and Advil do not heal a child. It lowers the fever temporarily. As it wears off, the fever returns, meaning the child's body is still trying to fight the virus. Our ped advises giving medication only if the child is very uncomfortable. If you immediately give medication, you supress the fever and not allow it to do it's job; therefore the child stays sick longer. I'm not totally against giving Tylenol or Advil; I will if my child is clearly uncomfortable. I will also give it at night because I think good sleep is important. At 13 you can ask if he is okay to hold onto the fever. My daughters, 8 and 6, were just ill and I gave them the option. Both said they would wait to take medicine. Eventually they clearly felt terrible and they asked to take it. My daughter was running a fever for 5 days, so I took her to the ped. who found she had an ear infection. So you should soon visit a doctor to determine if there isn't something else going on.
It is that time of year when everyone is getting colds, my son came down with the flu. Don't let your child lay around for days with a high fever, especially when tylenol and advil just mask the symptoms for a little while. Take him to a doctor.