(Reuters Health) - Teens and young adults who visit emergency rooms for injuries or physical illnesses may be more likely to harm themselves afterward, a U.S. study suggests.

Emergency room (ER) visits for mental health disorders or substance misuse have long been linked to an increased risk for self-harm and suicidal thoughts and behaviors among teens and young adults. The current study focused on teens and young adults, ages 15 to 29, who visited an ER for more common reasons: physical illnesses and injuries. It found that these individuals were much more likely to harm themselves after being treated for a wide range of conditions including epilepsy, back pain, headaches and dental problems.

The first weeks after leaving the ER may be when young people are most vulnerable. Half the episodes of self-harm occurred within 42 days of discharge.

“The mechanism underlying the association of the identified physical health conditions and self-harm is complex and not completely understood,” said study leader Dr. Jing Wang of the U.S. Centers for Disease Control and Prevention (CDC) in Atlanta.

“The presence of the specified physical health conditions may reflect some underlying mental disorders; however, common mental disorders can be found to be involved that do not completely explain the association of pain and suicidal behaviors,” Wang said by email.

Suicide is the second leading cause of death among U.S. youth and young adults, and suicide rates have been rising since 1999, Wang’s team notes in the American Journal of Preventive Medicine.

Understanding the link between ER visits and suicide risk may help prevent some of these fatalities, they write. About 40 percent of people age 16 and older who kill themselves visit the ER at least once in the year before their deaths.

Wang’s team examined data from six states on more than 2.1 million ER visits in 2012 and 2013. In about 8,500 cases, patients returned to the ER to be treated for an episode of self-harm within six months of their first ER visit.

Researchers compared with happened after initial ER visits for infections to the chance of a self-harm episode following visits for other physical ailments.

When people came to the ER for epilepsy or seizures on their first visit, they were about six times more likely to return for a self-harm episode within six months than counterparts with an initial visit for an infection, the study found.

For other conditions, visiting the ER once didn’t raise the risk of subsequent hospitalizations for self-harm, but visiting the ER twice did.

Second visits to the ER for various pain symptoms, blackouts, vomiting or injuries that were not self-inflicted were associated with a three to five times higher risk of a subsequent ER visit for self-harm.

The study can’t prove that ER visits for physical problems lead to self-harm or suicide attempts.

Some patients who returned to the ER after a suicide attempt may have had undiagnosed mental health conditions, said Nicholas Westers, a psychologist at the University of Texas Southwestern Medical Center in Dallas who wasn’t involved in the study. Self-harm also might be a coping mechanism.

“When physical and emotional pain seem to become intolerable or that they cannot be alleviated, individuals may opt to engage in non-suicidal self-injury to direct a controllable pain elsewhere on the body that may also distract from the physical pain, or they may opt to attempt suicide to end suffering without necessarily wanting to die,” Westers said by email.

Parents shouldn’t underestimate the stress that a trip to the ER can cause, said Dr. Mark Olfson, a psychiatry researcher at Columbia University in New York City who wasn’t involved in the study.

“Acute medical events, those serious enough to warrant a trip to the ER, can put vulnerable young people at increased risk of self-harm,” Olfson said by email.

To reach the National Suicide Prevention Lifeline, call 1-800-273-TALK.

SOURCE: bit.ly/2GwhDpz American Journal of Preventive Medicine, online December 17, 2018.