The "worried well" may be increasing their risk of heart disease, research suggests.
People who are anxious that they have - or will develop - a serious illness could be boosting their chance of the disease that can cause heart attacks, chest pain and heart failure.
Experts including a team from the Sandviken University Hospital, Bergen, in Norway, analysed data for more than 7,000 people for their study, published in the journal BMJ Open.
They said that while general anxiety was already known to increase the risk of heart disease, health anxiety might have its own role.
Health anxiety often refers to a preoccupation with having or developing a serious illness, despite medical investigations suggesting no sign of disease.
All the people in the research were born between 1953 and 1957.
They filled in two questionnaires about their health, lifestyle, and education, and underwent health checks including blood tests, weight, height, and blood pressure measurements between 1997 and 1999.
The heart health of all these people was then followed using medical records up to the end of 2009.
Researchers excluded those people who received treatment for heart disease or who died from it within a year of starting the study on the basis they they may have already been ill.
Overall, the results found that 234 people (3.3%) suffered a heart attack or bout of acute angina during the monitoring period, most commonly around the seven year mark.
Those people with health anxiety were twice as likely to suffer heart problems (6.1%) compared to those who did not (3%).
While other risk factors for heart disease - such as diabetes - explained part of the association, health anxiety was still linked to a heightened risk on its own.
The researchers said: "Persons with high levels of health anxiety have about 70% increased risk of heart disease relative to persons with lower levels after adjustments for established cardiovascular disease risk factors, including lifestyle factors."
The team stressed that their observational study could not prove that anxiety caused heart disease, but they said the findings "underline the importance of proper diagnosis and treatment of health anxiety".
Emily Reeve, senior cardiac nurse at the British Heart Foundation, said: "This study was observational and reached no firm conclusions about the effect of health anxiety on the likelihood of developing heart disease.
"It's natural for people to worry if they feel they might be unwell. But anxiety and stress can trigger unhealthy habits, such as smoking or eating badly, which put you at greater risk of heart disease.
"While we don't know if the 'worried well' are directly putting themselves at risk of a heart attack, it's clear that reducing unnecessary anxiety can have health benefits. If you are experiencing health anxiety, speak to your doctor."