I will admit - I didn't buy this for an infant. It's probably a good thing I didn't buy it for one. I was feverish and desperate to know what my temp was, so I grabbed this a few weeks ago from a local grocery store. Here's what you do: 1. Press the little button 2. Stick in your mouth/arm pit 3. Wait. 4. Wait. 5. Wait. 6. Wait. 7. Notice it hasn't beeped yet, look at it and determine that it's now turned off. Basically, this is as inefficient as you can get. Even for adults it's slow to read, never beeps and is unreliable. I can't even imagine it for children or infants.