“If a child was limping for two weeks, you wouldn’t think twice about having him evaluated, or if a child had headaches that wouldn’t go away, you would bring him to a doctor,” says Dr. Graham Emslie, a psychiatrist on the medical staff at Children’s Medical Center of Dallas. “But if kids have signs and symptoms of depression, we tend to wait much longer, thinking they’ll grow out of it or it will eventually go away.”

But that’s a mistake. Untreated, depression can have major long-term consequences. Teens could face an increased risk for substance abuse, difficulties with school and relationships, greater likelihood of future depression and even suicide.

According to the American Academy of Child and Adolescent Psychiatry, suicide is the third leading cause of death for 15- to 24-year-olds. While occasional periods of sadness are normal, depression tends to be more intense and pervasive, says Dr. Emslie. It lasts for several weeks, involves a change in behavior and interferes with life. Potential red flags include:

• Prolonged sadness, irritability or angry outbursts
• Withdrawal from favorite activities
• Dramatic changes in appetite, weight or appearance
• Sleep disturbances, excessive lethargy or restlessness
• Expressions of worthlessness or inappropriate guilt
• Inability to concentrate
• Preoccupation with death or suicide
• Physical complaints, such as stomachaches, with no evident causes
• Sudden drop in school performance
• Reckless behavior

If you suspect your child is depressed, see a qualified mental health professional at once. A diagnosis of depression often leads to treatment with a combination of psychotherapy and medication. Most people receiving treatment begin to feel better in two to four weeks.