Growing pains are leg pains that are common among rapidly growing children and teens. These pains are probably caused by differences in growth rates of muscle, bone, and soft tissue.
Growing pains typically occur in the thighs or calves. They can last an hour or two at a time and can awaken a child from sleep, but they usually produce no ill effects in the morning.
Growing pains do not occur with other symptoms of illness, such as fever or swelling, and are not considered harmful. The symptoms disappear over time.
Acetaminophen (such as Tylenol), warm packs, and massage often help relieve the discomfort of growing pains. A person younger than age 20 should never be given aspirin because of the risk of developing Reye syndrome, a serious illness.
WebMD Medical Reference from Healthwise