Teenagers love to text. Teenagers and young adults have a lot of questions about sexual health and sexually transmitted diseases. So it only makes sense that those who wish to disseminate information and help answer those questions would find a lot of value in text messaging.

Young people have a lot of the same questions about sex and sexual health as in years past, but the means of engaging youth have changed, Tom Subak, CIO of Planned Parenthood Federation of America said during a "Google Hangout" earlier this month on mobile health for youth. "It is really easy to ask a really tough question via SMS or via chat relative to what we all grew up with, which was having to get those words out of your mouth," Subak said during the online panel discussion.

The online session, hosted and sponsored by Internet Sexuality Information Services (ISIS), an Oakland, Calif.-based nonprofit, was meant as a promotion for the new mobile health track at YTH Live, the organization's annual conference, set for April. Similarly, Google has been using the event to promote "hangouts" on its Google Plus social networking site that is a decided also-ran in a world dominated by Facebook and Twitter.

Session moderator Deb Levine, founder and executive director of ISIS, noted that Subak had told her years earlier that young people tend to search for sex information when they are in crisis, such as being worried about an accidental pregnancy or transmission of an STD. Text messaging provides immediacy for people in a crisis situation. "They can just immediately dive in there with what's really on their mind in a way that I certainly don't think we were able to do before SMS was in everybody's hands the way that it is now," Subak said.

In 2006, Levine launched SexInfoSF – what she said was the nation's first SMS health program for youth – after telling the San Francisco Department of Public Health and said texting was the way to reach young people.

"As much as anything else, [text messaging] is a connector," Subak continued, not just to information, but also to health services. Subak said about 60 percent of 10,000 to 20,000 SMS contacts Planned Parenthood gets per month are referred to a health center.

Eric Leven, president of RipRoad, a provider of personalized, mobile patient health management services, helped build the technology for KNOWIT, a text-based HIV testing resource from the Centers for Disease Control and Prevention and the Kaiser Family Foundation. Leven reported that usage tended to peak after midnight when the program ran an outreach campaign on MTV. "In those early-morning hours, this was top of mind for a set of individuals, and we watched our volume spike," he said.

Sam McKelvie, head of mobile strategy at marketing firm Mobile Commons, said that finding the right platform to deliver a message is just as important as the message itself. "With teens, you absolutely have to reach them where they are at, which is online, on social, in promoting these things on the social media networks that teens are on," McKelvie said. She noted that Planned Parenthood also turned to MTV to market its SMS service for contraception and STD prevention education – appropriately during the show "16 and Pregnant."

McKelvie also said that teens in minority and lower-income communities tend to text more than more affluent peers because they have less access to the Web than others might. "Pay attention to who's exactly texting," she advised.

McKelvie further noted there are different kinds of SMS campaigns. Some are chat-like, where people can send in personalized questions. Others, like Do Something, a platform for encouraging young people to take an active role in social change, lets people opt in to receive more general information on a regular basis.

Even if a campaign is more informational than conversational, marketers should allow tow-way intereraction, McKelvie advised. It is a mistake, she said, to see text messaging as "a broadcast-only medium," particularly with teens.

Levine said one-way communication can work in some instances, such as when there is not sufficient capacity to respond immediately. "People expect a text message response pretty much, like, yesterday," she said.

Planned Parenthood is among those with a two-way text system. "That's a real resource commitment," Subak acknowledged. The women's health organization has has analyzed the 1,000 or so most popular questions, so responders can mine a knowledge base for quick answers that have proven to be helpful with earlier queries, Subak said.

Still, mass texts blasts do have their place. "Broadcast messages can be very helpful," such as in the case of a pertussis outbreak, said Dr. Pamela Johnson, co-founder and chief health officer of Voxiva, the content developer for such SMS outreach programs as Text4Baby and Text2Quit. Text4Baby, a prenatal and maternal health service, become more interactive over time, Johnson said, conducting surveys such as whether pregnant women and new moms have gotten flu shots.

Text4Baby got its 500,000th registration in February, Johnson said. While that still is far short of the 1 million program co-sponsor the National Healthy Mothers, Healthy Babies Coalition forecast by the end of 2012, it is still a large number. "We set out to show that mobile health could have a large-scale impact," Johnson said, adding that many women stick with the program for a full year after their baby's birth.

"If we're trying to reach large populations, SMS works extremely well," Johnson said.

"Public health, the real issue we all face in our work is reach. Text messaging really is the ideal medium to get the broadest reach."