By Andrea Petersen

In a time when almost everyone shares almost everything, the question of boundaries between a doctor and patient is thornier than ever.

Beyond the obvious no-go areas of sex and abuse, the relationship can be fraught. How do you reply to the chatty doctor who name-drops other patients—including your co-workers? Can you invite your dermatologist to dinner?

Doctors are divided on how strict the boundaries should be. Some have firm rules against socializing with patients or revealing personal details about their own lives. Others say a closer relationship can build trust and make it more likely patients will follow medical advice. The growth of social media complicates things, too, especially as a generational shift means young digital natives are entering the medical profession.

Before, “you would see your patients in the hospital, or you’d see them in your clinic or, maybe, at a party,” says Sigal Klipstein. “Now you can reach out to your patient and your patient can reach out to you in a lot more pathways.” Dr. Klipstein doesn't accept Facebook requests from patients on her personal page. And while she’s sometimes invited to christenings for patients’ babies, she doesn't attend.

Wayne J. Riley, says doctors should “adopt a posture of warm detachment,” with their patients.

Professional medical organizations are issuing new and updated policies to help doctors navigate these tricky questions. A new policy on digital and social media was released in February, that included a warning about venting about patients—even anonymously—on social media. Another said doctors “should not ‘friend’ or contact patients through personal social media” or text “for medical interactions with even established patients except with extreme caution and patient consent.”

A 2010 paper proposed rules for the phenomenon of patient-targeted googling. It noted that in a survey of several dozen psychiatrists, most searched for information about their patients online. It warned against doing so because of “curiosity, voyeurism and habit.”

Some boundaries are clear. Professional medical organizations have strict rules against sex and romance with patients. Doctors are also advised not to treat family or close friends, situations that could compromise objectivity and judgment.

The Health Insurance Portability and Accountability Act (HIPAA) establishes national rules to protect the privacy of patients’ health information. Under HIPAA, it is a no-no to name-drop other patients. And if a doctor sees a patient in a public setting, the physician isn’t supposed to acknowledge that the person is a patient—unless the patient reveals the relationship first.

If a doctor does cross the line, patients can file a complaint with the Office for Civil Rights at the U.S. Department of Health and Human Services, which oversees HIPAA.

“What would likely happen is that we would give that provider a call and counsel them about what the rules require,” says Deven McGraw, deputy director for health information privacy in the Office for Civil Rights.

Wanda Filer, a practicing family physician in York, Pa., says she finds that disclosing some information about her own life helps “break down that barrier as you build that relationship [between doctor and patient]. They are more willing to tell you other things that are going on.” She will joke about her own colonoscopy and recently commiserated with a patient over their mutual kitchen renovation projects. Dr. Filer, says she has attended the funerals of several patients and recently spoke at one. She gives some patients her cellphone number. That intimacy, however, can spill over to outside the office. “I’ve had patients have all sorts of graphic conversations at the gas station, the dry cleaners,” she says. “They’ll lift their shirts up and show you a mole.”

In one 2007 study, primary-care doctors disclosed personal information about themselves in 34% of visits with new patients. The researchers, however, concluded that 85% of those disclosures weren't “useful” to the patient. In another study, published in 2004, researchers found that when primary-care physicians disclosed personal information about themselves, patients were less satisfied with their visits and were less likely to report feeling reassured or comforted. The findings were the opposite, however, when surgeons self-disclosed: Surgical patients were more satisfied and reassured.

Nick van Dyk says having a close relationship with his doctor has made him more confident in his medical treatment. Mr. van Dyk, a Los Angeles film and television executive, has been treated for multiple myeloma, an often-fatal blood cancer, since 2009. He has dinner and drinks with his hematologist, Bart Barlogie, a few times each year. He has Dr. Barlogie’s cell number and will call with questions or concerns—even on nights and weekends. “I would consider Bart a friend,” Mr. van Dyk says. “I know there is nobody in the world fighting harder for me to beat this disease.”

Dr. Barlogie says he considers his patients “family.” Many traveled long distances to be treated by him at the University of Arkansas for Medical Sciences in Little Rock, Ark. So Dr. Barlogie and his wife made a habit of taking patients to dinner. The doctor always paid.

“When people didn’t have family with them or were distraught or lonely, we wanted to make them more comfortable,” says Dr. Barlogie, who, after 27 years in Little Rock, moved to become the director of research for the myeloma program at Mount Sinai Health System in New York. “It is something we did with joy, and when we saw it was helpful we did it more.” When he sees marriages beginning to crumble under the stress of fighting a deadly disease, he’ll try to intervene. “I made it my business to try to fix it,” he says.

Doctors in small towns say they really have no choice but to be close to their patients. Jen Brull is a family physician in Plainville, Kan., population 2,000. She sees her patients at her children’s school, at church and at the grocery story. She lets patients friend her personal page on Facebook and invites them to the 5 a.m. exercise group she attends.

“If I had to separate my patients and friends, I would either have no friends or no patients,” Dr. Brull says.