Which kind of thermometer works best for kids?

Therese Delashmutt was really worried about her son Gabe.

"He had a stomach flu, throwing up. We didn't know what it was," she said.

There was no way he'd keep a thermometer under his tongue or his arm.

"We tried each one, a new one every time he got sick and when it didn't work we'd try another one," she said.

With so many options, the National Institute of Health is conducting a study on the accuracy of oral, ear and forehead thermometers.

Experts say age matters. For kids under 6 months:

"The most accurate way to do it is through a rectal thermometer but a lot of parents don't want to do that on a regular basis if the baby might not be that sick, so it's perfectly fine to do an underarm thermometer," said Dr. Jenifer Shu.

For children older than six months, try an ear thermometer or the temporal type:

"Swipe it across the child's forehead and behind the ear and that tends to be very reliable also for 6 months and over. It's very easy because the child doesn't have to sit still for very long and it's incredibly fast and painless," said Dr. Shu.

That's what worked for Gabe.

"At first he was hesitant and then he was all about holding his hair up," said Therese.

There are also strips that sit on the forehead, pacifier type models, even some that light up in the dark. Methods can vary by a few degrees, so be sure you tell the doctor which one you used.

One more bit of advice: Wait at least 15 minutes if your child was outside in the cold or if they've eaten something cold or hot. You'll get a much more accurate read of what's going on.

Mercury thermometers are no longer recommended since they pose an environmental hazard.