Many people have at least one toxic friend, nasty coworker or hateful relative in their lives. But the bad blood caused by those bad relationships may actually be harmful: stressful social interactions contribute to an increase in risk of high blood pressure in women, accoa srding to tudy released this week.

“What we observed was as the amount of negativity in relationships increased, risk of hypertension [in women] also increased,” says report co-author Rodlescia Sneed, Ph.D candidate at Carnegie Mellon University.

Sneed and co-author Sheldon Cohen, the Robert E. Doherty University Professor of Psychology at CMU, analyzed data from 1,502 healthy adults over 50 who were part of the multi-year study known as the Health and Retirement Study. The survey captures information about the physical health, such as blood pressure, and psycho-social health, such as relationships, of more than 26,000 Americans every two years.

The researchers examined data from 2006 and 2010, specifically looking at the number of negative social exchanges and blood pressure. Negative social interactions— incidents including excessive demands, criticism, disappointment, and disagreeable exchanges— were related with a 38 percent increase in developing high blood pressure in women. Younger women, aged 51 to 64, saw more of an effect than older women.

While the researchers looked at negative social interactions and hypertension with both men and women, only women showed a link between bad relationships and high blood pressure.

“There is a lot of evidence that women pay more attention than men do and care more about their relationships than men do and it can be particularly devastating,” says Sneed.

Previous research has shown women in a bad marriage are at more risk of heart disease, stroke and diabetes. This study suggests you don’t have to be married to a jerk to suffer.

“It is a really important study; this is looking at the development of health problems,” says Bert Uchino, a professor of social psychology and health psychology at the University of Utah, who was not involved in the study. “I don’t think that people realize … how these [psycho-social] factors can impact [our] long term health. Our relationships are very important, not just for our mental health, and they appear important for how long we live,” he says.

Another interesting finding — negative interactions with friends and family members impact blood pressure more than a conflict with a child or partner. It’s possible older adults might have more stable relationships with their partners, creating less strain, Sneed says. And, parents might always expect their children to make demands or be difficult, perhaps making those interactions seem less stressful.

“Perhaps, we expect that level of negativity in those types of relationships,” says Uchino.

David Frid, a cardiologist in Preventative Cardiology and Rehabilitation at Cleveland Clinic says this study serves as a good reminder for physicians.

“It again reinforces that psycho-social factors are important in the development of hypertension and important in overall health,” he says. “It just tells us that we can’t ignore [relationships] in part of an assessment of people’s.”