Cheryl,
In general we have two types of temperature sensors, IC temperature sesnors, and an IR temperature sensor.
Measuring body temperature with an IC temperature sensor can present many challenges. The IC temperature sensor is designed to measure the temperature of a printed circuit board. The main thermal path is through the pins of the device that are soldered down to the printed circuit board. Even if the package is pressed against skin, the heat generated by the human body is not directly seen by the die of the sensor inside the package. This leads to inaccuracies in what the sensor reports as the temperature that it sees versus what the actual temperature is. This is important to take into account in your application depending on how accurate you are trying to be.
The other option is an IR temperature sensor which also can present some challenges. Below is a link regarding this type of measurment and the TMP006.
http://e2e.ti.com/support/other_analog/temperature_sensors/f/243/p/116247/447807.aspx#447807
If you could provide some more insight to your project we may have some better solutions for you.