DS just had this a week ago. His fever was 103 at 11am and by the time they took his temp at the doctors office 20 mins later it was 105.2! He was totally out of it!
Anyway, the reason we ended up at the doctors in the first place was that the ibuprofin alone wasn't keeping the temp down. He was running 102 and up when on a full dose of motrin! The doctor said to do a full dose of motrin and take his temp 3 hrs later. If the temp was over 101 then give a full dose of tylenol at that time. Take the temp 3 hrs later again and if still over 101 give a full dose of motrin. We actually had to get the liquid childrens motrin and liquid childrens tylenol because it turned out with the pills(DS is 10 and can swallow adult pills) when we gave him one adult motrin, we were actually giving him 50mgs less than what he needed. Point of the story, if one med wasn't cutting it, we were to go to a 6 hour dosing and alternate the other med at the 3 hr mark. By the second day we were back to only needing the motrin and then we were allowed to use it every 4 to 6 hours instead of a strict 6 hours when alternating. Sorry so long and complex but DS's fever was quite high too and the Dr was concerned. He said if we had any vomiting to go to the ER or if we had a sustained temp of 105 or higher to go to the ER. Obviously, we were to treat the fever with meds, room temp bath, cool cloth, etc but if it stayed at 105 or higher without us being able to bring it down, then it meant a trip to the ER.