Children who are bullied also suffer other ailments perceived to be unrelated to the incidents.
Kids who were regularly bullied were found to be twice as likely to "not feel well" than kids who had a healthier social life, HealthDay reported.
Researchers analyzed over 220,000 children over the course of 30 studies, and found "headaches, stomach aches, back aches, neck or shoulder pain, dizziness, trouble breathing, tense muscles, nausea, diarrhea and bedwetting" were the most common symptoms of frequent bullying.
"The results of this study suggest that any recurrent and unexplained physical symptom can be a warning sign of bullying," study author Gianluca Gini, an assistant professor of developmental psychology at the University of Padua, in Italy, told HealthDay.
The researchers believe looking out for these warning signs and "asking the right questions" could be the key to determining if a child is being bullied.
"Children do not easily talk about their bullying experiences," Gini said, but she stressed the importance of getting them to open up.
Gini believes bullying should be viewed as a "significant international health problem," the Globe and Mail reported.
Gingi said other warning signs that teachers and parents should be on alert for is "anxiety, depression, fears about going to school, lack of friends, unexplainable injuries, lost or destroyed personal clothing, books or electronics, declining grades or lack of interest in schoolwork."
"I think the first thing is really finding time to really observe, watch, and talk with kids so you know when something is off," said Snyder, who was not involved in the research. "Ask them questions: 'How was your day? Who did you sit with at lunch?" Marlene Snyder, a faculty member in the Institute on Family and Neighborhood Life at Clemson University, told HealthDay.
"You have to start taking a look at what's happening with the friend routine. Has the phone stopped ringing? Are they afraid to check their text messages? There are so many things that can tip off an aware parent," she said.
