Once a patient has been diagnosed with an FUO, attention should be paid to every aspect of the medical history. A thorough medical history, even in a patient one has known for years, may catch potentially unknown historical features. Within the medical history, the clinician is searching for diagnostic clues. In particular, the medical history should address the following:- Fever – The febrile illness, including its onset, course, and response to therapeutic trials.- Exposure history – All exposures should also be obtained, including information about sick contacts, sexual activity, lifetime tuberculosis contacts, occupational and recreational activities, and exposure to animals.- Prodromes – Recent prodromal symptoms, such as a sore throat, myalgias, or arthralgias, may be useful.- Diet – Dietary history, including specifics about the origin of meat, dairy products, and vegetables consumed may provide important historical clues.- Travel history – A complete lifetime travel history, including itineraries within and outside the home country, should be ascertained.- Military service – This should be determined because it may point to a number of exposures.- Past medical history – Prior illnesses, infections, malignancies, surgeries, invasive procedures, implantation of prosthetic devices, and blood transfusions should also be ascertained.- Medication history – A detailed history of medications, including any herbal supplements, is important in determining potential clues for drug fever. Exposure to any immunosuppressive drugs can broaden the likely differential diagnosis.- Illicit drugs – Illicit inhaled and intravenous drug use during the patient’s lifetime should be identified.- Family history – An exhaustive family history should include any family members with prior tuberculosis or other infections, collagen vascular diseases, malignancies, or febrile syndromes. Ethnic origin should also be noted.- Review of systems – A complete review of systems is often helpful in obtaining potential diagnostic clues to guide further investigation. Repeatedly revising the review of systems may be helpful in finding clues not previously appreciated on prior interviews. Positive findings might lead to clues of local disease or a constellation of findings suggestive of certain systemic illnesses. Uncommon symptoms may be discovered.*150/348/5*