Taking your child's temperature can help you know if they have a fever. For most infants and young children, you can take a rectal temperature with a digital thermometer. A rectal temperature is taken by gently putting the tip of a thermometer through the anus (the hole where poop comes out) into the rectum.

Take your child's temperature with a digital thermometer labeled for rectal use. Follow the instructions that came with the thermometer. In general:

1. Clean the thermometer before use. You can wipe it with rubbing alcohol on a cotton pad or wash it with soap and water, then rinse with cool water.
2. Turn the thermometer on.
3. Coat the tip of the thermometer with a lubricant, such as petroleum jelly.
4. Place your baby:
   • Belly-down across your lap or on a firm, flat surface, and keep your palm along the lower back
     or
   • Face-up with legs bent toward the chest with your hand against the back of the thighs
5. With your other hand, put the lubricated thermometer through the anus into the rectum. The thermometer should be about ½ to 1 inch (about 1.25 to 2.5 centimeters) into the rectum. The thermometer should slide in easily. Stop if you feel like you need to force the thermometer in. Note the angle of the thermometer in the picture above.
6. Steady the thermometer between your second and third fingers as you cup your hand against your baby's bottom. 
7. Wait with your child until the thermometer signals that the temperature is ready to view.
8. Remove the thermometer gently and write down the number on the thermometer screen and the time of day.
9. Turn the thermometer off.
10. Clean the thermometer with either rubbing alcohol or soap and water. 

Other reminders: 

• A rectal temperature of 100.4°F (38°C) or above means your child has a fever.
• Wait 20–30 minutes after your child has a bath or has been bundled tightly to take the temperature.
• Never use a glass/mercury thermometer. They can break and cut your child and expose them to mercury (a harmful chemical). 

• You have questions about how to use the thermometer.
• Your child has a fever.

Your baby is younger than 3 months and:

• Has a rectal temperature of 100.4°F (38°C) or higher
• Has a rectal temperature of 97°F (36.1°C) or lower