12 years old with a fever of 39.5 degrees Celsius and during the physiological period. At this stage, we should pay attention to choose the appropriate way to reduce fever, can be through the combination of medication and physical fever, and pay attention to dietary habits adjustment. 1. Drugs to reduce fever: body temperature over 39.5 degrees Celsius must be medicated to reduce fever, can take ibuprofen suspension or acetaminophen under the guidance of a doctor, can be in the forehead, armpits and other parts of the paste fever patch for physical fever reduction. If there is inflammation in the body, you can take Pu Dilan anti-inflammatory oral solution. 2. Dietary habits adjustment: is in the physiological period, pay attention to drink more water, which can accelerate the body metabolism, drink water must pay attention to drink warm water, diet more to mild food and fresh fruits and vegetables mainly. The 12-year-old fever of 39.5 degrees Celsius, and in the physiological period, can be based on the symptoms of the disease symptomatic treatment, can not determine the cause of the case, you can go to a professional hospital for treatment.