My 9-year-old came home from a day of skiing and said his eyes hurt. They looked a little red. He had been wearing goggles all day, but I felt a pang of worry: Could it be snow blindness? (He was fine.)

I've had similar experiences with my own health. I might have jaw pain, dizziness or a stomach flu that makes me vomit. Before long, I'm wondering about heart attacks, tumors, even Ebola.

Usually, I manage to rationalize away my fears, especially when symptoms go away — until a new problem arises. Then, even when I try not to look, I end up online, searching for signs of my own imminent demise.

I'm not the only one with a tendency to jump from physical ailment to worst-case scenario. An informal poll of friends turned up a list of inaccurate self-diagnoses that included malaria, multiple sclerosis, West Nile virus, a femoral hernia, cancer and a post-hysterectomy pregnancy.

Health anxiety is extremely common if not universal, says Thomas Fergus, a clinical psychologist at Baylor University in Waco, Texas. With so much health information available online, most people search their symptoms at some point. That's not necessarily a bad thing. The anxiety that often ensues may be short-lived or even helpful.

But sometimes the worry becomes its own kind of problem, leading to a preoccupation with illness that persists even after doctors offer reassurance.

"Everyone is going to be anxious about their health from time to time," Fergus says. "What makes it a problem is the frequency, the intensity and the severity."

People who worry excessively about their health used to be called hypochondriacs. But that term developed negative connotations, and psychologists dropped it in 2013. The latest edition of the Diagnostic and Statistical Manual of Mental Disorders replaced hypochondriasis with two alternatives: somatic symptom disorder and illness anxiety disorder.

Both diagnoses remain controversial. Some doctors argue that they are overly general, putting too many people at risk of being unnecessarily diagnosed with a mental illness. Partly because the terms are so new, there is no clear statistic on how many people have clinical levels of health anxiety.

But the Internet has become a potential breeding ground for health anxiety, according to researchers who use the term "cyberchondria" to describe the interplay between online health searches and health anxiety.

WebMD, the Mayo Clinic and other websites allow users to enter symptoms in exchange for a list of possible diagnoses, and most people end up searching at some point. A 2013 survey of more than 3,000 American adults by the Pew Research Center reported that 59 percent had searched online for health information in the previous year. And 35 percent said they had used the Internet looking specifically to diagnose a medical condition. Fergus says other studies have shown that 60 to 80 percent of people look online for health information.

In some cases, that kind of research can be helpful and a little dose of anxiety can motivate people to finally seek out the health care they need. Once in the midst of testing and evaluation, Fergus adds, it's normal to experience a heightened state of anxiety.

But searching for health information can magnify the pool of potential problems to worry about, and studies suggest that people who are prone to health anxiety are most vulnerable to getting sucked in. Anxiety levels also tend to be higher, Fergus says, when people think there is a higher chance that they have a problem and when the burden of having that problem would be particularly large — if, say, a family member was diagnosed with a disease or if the consequences of the disease would be devastating.

Health worriers share other features, too, says Karmpaul Singh, a research psychologist at the University of Calgary, who has published three studies on health anxiety in the past few years with Richard J. Brown at the University of Manchester in the United Kingdom. Echoing previous work, their findings have shown that those with higher levels of health anxiety tended to be most uncomfortable with uncertainty. Instead of waiting something out or rationalizing it away, they went looking for answers.

"It's really that discomfort with the unknown," Singh says, "that draws them in to Googling a symptom at midnight instead of waiting to see if it disappears."

People with health anxiety also tend to jump to catastrophic outcomes when symptoms arise, Singh says. They may seek out information that confirms their worst suspicions. They resist reassurance. Or they consider unlikely diagnoses, even if there is only a tiny chance of their being responsible.

Singh once had a student who thought a mole on her arm was a sign of cancer even after her doctor said it was benign. She went on to visit several doctors, who all said the same thing. Still, she went home every night and circled the mole with a Sharpie to see if it was growing.

When health worries persist after test results are negative or doctors say that nothing is wrong, it might be a sign that the anxiety needs extra attention, Fergus says, especially if the anxiety sticks around for months or more. Missing school, work or time with friends to spend hours on patient forums or Google searches is another warning sign.

"Once something becomes so preoccupying that it takes away from your quality of life, no matter what it is, that's the point when you should see a psychologist or psychiatrist," Singh says.

Anxiety is worth taking seriously because it can carry health consequences of its own. Studies have linked anxiety with higher rates of heart attacks in people with heart disease. And treating anxiety has been shown to improve symptoms in people with chronic respiratory and gastrointestinal diseases.

Relaxation exercises, such as yoga and meditation, can sometimes help people conquer health anxiety, Fergus says. But when people can't manage anxiety on their own, he suggests seeking professional help.

For people who choose to look online, sussing out high-quality sources of information is one way to avoid falling into rabbit holes. Most people look only at the first page of Google results, studies show. And they tend to trust sites as long as the grammar looks sound and they see the word "doctor." Singh recommends looking away from the rare diseases and sticking with the most reliable sources, such as the Harvard School of Public Health and the Mayo Clinic.

He also advises trusting the medical process, which is far more likely than self-diagnosis to deliver accurate answers. In a 2016 study, online symptom-checkers got the right answer on the first try just 34 percent of the time, while doctors nailed it at a rate of 72 percent.

A little bit of self-reflection can go a long way, he adds. He developed health anxiety as a teenager, convinced that aches, pains or coughs were leading him to organ failure. Since then, his research has made him aware of what was happening and helped him stop jumping to conclusions, in part by avoiding health-related websites. "I still Google symptoms once in a while," he says. "It doesn't bother me anymore because I've learned a lot about it."