SAN ANTONIO -

Football season is under way and many high school students are ready to take to the field.

However, the more play time a student gets, the more at risk for injury and concussion that student will be.

Dr. Lillian Lao, pediatric trauma director at University Hospital, said if a student gets a concussion on the field, the most obvious sign is losing consciousness.

But even if the student appears OK after a blow to the head, Lao said parents really need to pay attention to other symptoms.

"The first concussion may not have any major symptoms," she said. "And the child might do fine, but when they get hit again, the second hit phenomenon can cause death and that's what we are trying to prevent."

Lao said if a student experiences dizziness, light-headedness or even sensitivity to light, parents need to seek treatment right away.

"When you have a concussion, your brain is injured or bruised," said Lao. "And, it needs time to rest, just like any other injury, such as a bruise on your arm or a broken leg and the time it can take to heal from a concussion can be anywhere from a week to six weeks."

There is now an "app" to test for concussions by getting readings for balance, reaction time and vision.

There are also products that fit under helmets that will trigger a check-light if there's a possible injury (pictured below).

Lao said while all these products to track injuries are helpful, she said the real test is how a student feels when he or she gets off the field.

"The most important thing is to watch for signs and symptoms that your child has developed after they have sustained a blow to the head," Lao said. "We are very focused on football because we live in Texas, but that can happen after a child has fallen off a bicycle or a skateboard."

For more information on concussions or to request a free youth sports tool kit, you can check out the Centers for Disease Control Web site at cdc.gov.

For a list of recent stories Stephanie Serna has done, click here.