CHICAGO (CBS) – These days, we let our thumbs do the talking, with more than one and a half trillion text messages sent over mobile phones last year alone. That averages out to five billion messages a day.

All this typing could actually lead to injury. CBS 2’s Susan Carlson reports on a new condition that some doctors have dubbed “texting thumb.”

Try as she might, Malisa Meresman can’t seem to get away from her Blackberry.

“I’m on my Blackberry almost all day, because for work I use my Blackberry. At night, I’m texting my friends,” said Meresman.

But one day, her thumb started to hurt.

“It’s very achy. It gets stiff. And it actually does hurt to text,” she said.

It turns out Meresman was suffering from a repetitive stress injury caused by frequent texting.

“We have to flex or bend the thumb or the index finger to such an extreme that, that repetitive motion over time gives problems to some of those joints,” said Dr. Kevin Plancher, Plancher Orthopedics and Sports Medicine.

Dr. Plancher says these seemingly small symptoms now could lead to bigger problems in the future.

“Repetitive injuries, one, are painful for many patients, and the other is that they can develop over time, arthritic conditions,” he said.

The injuries are similar to those caused by excessive typing, adds Dr. Leon S. Benson of the American Academy of Orthopedic Surgeons. But texting affects different joints.

“Instead of necessarily getting tendonitis in your wrist, inflammation in your wrist from typing a lot, you can get symptoms in your fingers because you’re working on a tiny keyboard,” Dr. Benson said.

So what’s a frequent texter to do? Experts suggest slowing down, taking frequent breaks, and switching the way you hold your phone or the fingers you use to type with.

“You can also exercise. You can stretch out your thumbs, you can stretch out your index fingers,” Dr. Plancher said.

Malisa Meresman was able to use ice and anti-inflammatory medication to relieve her achy joints, and now she tries to text less often.

“I try to just be a little more aware of when I’m texting and when I don’t need to be,” she said.

In addition to texting, experts suggest you limit your child’s hand-held video game use, which requires the same kind of repetitive movements.

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