One and a half year old baby fever 40 ℃ treatment measures include: drug antipyretic, physical cooling, timely medical attention. 1. drug antipyretic: fever 40 ℃ belongs to high fever, due to infants and young children cerebral cortical development is not perfect, in the case of high fever is easy to induce febrile convulsions, parents first need to give the child in a timely manner to reduce the temperature and fever, the current guidelines recommend safe antipyretic drugs for children, including ibuprofen and acetaminophen, all need to be based on the weight of the calculation of the drug dosage, interval of 6 hours or so, the application of a time. 2. Physical cooling: physical cooling is equally important, parents should not cover the baby sweat, less wear less cover, room temperature control at 24-26 ℃ is appropriate, you can also choose warm water to help the baby wipe palms, feet and other parts of the body to help reduce fever. In addition, fever will increase water evaporation, parents need to give the child more water to avoid dehydration. 3. Timely medical: one and a half year old baby fever 40 ℃ is due to bacterial or viral infections, it is recommended that after the heat treatment timely medical care, the need for routine blood, C-reactive protein, if necessary, imaging aspects of the examination to clarify the situation of the infection, the use of antibiotics such as cephalexin as prescribed by the doctor. High fever in infants and young children can easily lead to convulsions, dehydration and other serious complications, so parents need to immediately medication and physical antipyretic, and then promptly seek medical treatment.