(Reuters Health) - At least one in four teens are receiving sexually explicit texts and emails, and at least one in seven are sending sexts, a new study suggests.

FILE PHOTO: A man uses a smartphone in New York City, in this picture taken November 6, 2013. REUTERS/Mike Segar

Sexting can be a healthy way for young people to explore sexuality and intimacy when it’s consensual, said lead study author Sheri Madigan of the Alberta Children’s Hospital Research Institute and the University of Calgary in Canada. The trouble is that when it’s coerced, or when sexts are shared without permission, it can feel a lot like cyberbullying, with many of the same dangerous mental health consequences.

More than one in 10 teens are forwarding these sexts without consent, the study found. And roughly one in 12 teens have had sexts they sent shared without their permission.

“Today’s teens often do not separate their online and offline lives - it is all the same to them,” Madigan said by email. “This is hard for parents to grasp.”

Most teens don’t report sexting at all, and those who do send or receive sexually explicit messages, videos or images tend to be older, researchers report in JAMA Pediatrics.

Researchers examined data on sexting habits from 39 previously published studies with a total of 110,380 teens. Participants were 15 years old on average, although they ranged in age from about 12 to 17.

Because kids today typically have a smartphone by the time they’re 10 years old, parents should address sexting as part of any early conversations they have with kids about practicing safe sex and protecting their privacy online, Madigan advised.

“It can be helpful for parents to think about sexting in the same way they think about sex,” said Elizabeth Englander, author of an accompanying editorial and director of the Massachusetts Aggression Reduction Center at Bridgewater State University.

Rather than forbid sexting outright, parents should be teaching children to consider the consequences of doing it and help kids understand how to resist pressure to do anything that makes them feel uncomfortable, Englander said by email.

“Youth think of adults as worriers and as over-estimating risk, particularly when technology is involved, and many will tune out adults who just tell them `don’t do this,’” said Lisa Jones, a researcher at the Crimes Against Children Research Center at the University of New Hampshire in Durham.

“But sexting can be risky, and certainly nonconsensual sharing of explicit images is hurtful and even potentially criminal,” Jones, who wasn’t involved in the study, said by email.

The study wasn’t a controlled experiment designed to prove whether or how sexting might cause health problems for teens. Another drawback is that many of the smaller studies in the analysis used different definitions of sexting that made it difficult to determine how often teens are sharing explicit words, videos or photos.

Still, the results emphasize the importance of frank discussions about safe sexting, Jones said.

“Youth need to have adults providing them with accurate information,” Jones added. “Cautionary messages about sexting are going to be most effective if they are embedded in youth education on romantic relationships, treating others respectfully, responding to sexual pressure, and making healthy decisions about sexual behavior.”

The safest way for teens to sext is to avoid sharing any pictures they wouldn’t want every person at school to see, said Dr. Matthew Davis, a researcher at the Ann & Robert H. Lurie Children’s Hospital of Chicago and Northwestern University Feinberg School of Medicine.

“Because sexts are permanent and so easily sent from person to person, sexts can turn a natural and usually fairly private part of growing up into a public and often emotionally distressing problem,” Davis, who wasn’t involved in the study, said by email.

“When youth share sexually explicit photos, videos, or messages, they put the subjects of the sexts at risk for bullying and cyberbullying and the mental health risks that can follow,” Davis added. “That’s especially true when the sexts are forwarded without the subjects’ permission.”