It's a rule many residents learn in training. If a patient says he has four drinks a week, consider it eight. The same for cigarettes and illicit drugs, doctors say.
The not-so-subtle message underlying the practice: patients lie.
"It's just human nature that patients want to please doctors," says Kevin R. Campbell, a cardiologist in Raleigh, N.C.
"I've had patients say they quit smoking and yet they come in smelling like tobacco," he adds. "I can throw pills and drugs at patients all day long but if they're still continuing to smoke and that sort of thing it's just not going to help."
Patient lies—from half truths and deceptions to bold, blatant lies—are surprisingly common and can be hard to detect in today's hurried medical practices, doctors say. And as many doctors strive to move away from a stern and lecturing stereotype, confronting patients without alienating them can be especially challenging.
Common lies include everything from diet and exercise regimens to medication adherence, sexual histories, and taking alternative medicines. Doctors say some patients play down symptoms out of fear of a diagnosis or hospitalization. Others play up symptoms to obtain something such as a handicapped parking permit or a controlled substance.
In what may be a sign of the mistrust: however often patients lie, their health-care providers think they lie more. In a 2009 survey, 28 percent of patients surveyed acknowledged sometimes lying to their health-care provider or omitting information. But the health-care providers surveyed suspected worse: 77 percent said that one-fourth or more of their patients omitted facts or lied, and 28 percent estimated it was half or more of their patients.
The survey, conducted by General Electric Co. with the Cleveland Clinic and Ochsner Health System, included more than 2,000 people and more than 1,200 doctors and other medical personnel.
Patients ages 25 to 34 were more likely to lie than older patients, according to a 2004 online survey of 1,500 respondents conducted by consumer medical news website WebMD. And men were two times as likely to get caught lying as women.
Some patients lie out of embarrassment or fear of disappointing a doctor. Others worry about electronic medical records or information being communicated to employers, insurance companies or the authorities.
Doctors say omitting important information or lying can lead to the wrong treatment, medicine or even diagnosis.
Jeffrey Cain, a family doctor in Denver, had a patient whose blood-pressure medication didn't appear to be working, so he changed the prescription. "What he hadn't told me was he wasn't actually taking his blood pressure medicine," Dr. Cain says.
The patient read a story about heart disease that scared him and then started taking all his medications—new and old. His blood pressure dropped so low that he passed out, Dr. Cain recalls.
In some cases, Dr. Cain says, patients are lying to themselves. They want to project to their doctor the image they want for themselves. Sure, I'm watching what I eat, Doc. Yes, I exercise regularly.
Maureen Mack is guilty of that. The 42-year-old tells doctors she exercises three times a week, 30 minutes each time. Reality is more like once or twice a week for 15 minutes.
"Why do I do it?" says the public-relations director who lives in a Milwaukee suburb. "Because I'd like to set myself a standard and try to live up to it so every time I write it I convince myself that I'm going to do it and the next time I go to a doctor it will be true. Hasn't happened in nine years."
Ari Brown, a pediatrician in Austin, most often catches parents lying to her when they disagree. Dr. Brown, for example, believes babies should be off a pacifier by six months or a year due to potential dental or language issues. Once, a mom said her daughter had given up her pacifier. It didn't come up again until the girl, then 2½ years old, fished a binky out of mom's purse during a visit and popped it into her mouth.
"The mom was like, 'Oh thanks, you totally just outed me,' " Dr. Brown recalls.
"I think that parents probably lie or omit information when they feel like they might be judged," Dr. Brown says. As a pediatrician for 17 years, she says she used to be more confrontational. "Now it's kind of, we just leave it out there."