Why does heartbreak hurt so much? Science has the answer

woman lying on her bed on her phone looking upset
(Image credit: Getty Images)

Falling in love can feel intense and often leaves people giddy and euphoric. But severing that connection can trigger a rush of negative emotions that can feel physically painful too.

These negative emotions are influenced by hormones — with increases in the stress hormones cortisol, adrenaline and noradrenaline, and reductions in happy hormones serotonin and oxytocin within the body.  These "heartbreak hormones" may also cause the physical symptoms that lead people to feel pain.

Here’s the science behind why heartbreak is often painful.

Why does heartbreak hurt so much?

There is a physiological reason why heartbreak can be such a painful experience, said Dr. Deborah Lee, a medical writer for Dr Fox Online Pharmacy in England, and symptoms aren't just in the mind.

"When you fall in love, there is a natural outpouring of hormones," she told Live Science. These include the 'cuddle' hormone oxytocin and the 'feel-good' hormone dopamine. But when you fall out of love, levels of oxytocin and dopamine drop, while at the same time there is an increase in levels of one of the hormones responsible for stress — cortisol." 

These raised cortisol levels can contribute to conditions such as high blood pressure, weight gain, acne and increased anxiety, Lee said. 

Social rejection, such as breaking up with a partner, also activates areas of the brain associated with physical pain, noted a 2011 study in the journal Biological Sciences. Participants who had recently been "dumped" were shown a picture of their ex-partner. Magnetic resonance imaging (MRI) scans found that areas of the brain usually associated with physical injury, including the secondary somatosensory cortex and dorsal posterior insula, were activated. 

Sad young man standing by the window at home and contemplating.

(Image credit: Getty Images)

"The neurobiological effects of heartbreak can reach such heights that it has been likened to that of physical pain as evidenced both by self-reported physical symptoms, such as chest pain and panic attacks, and sufferers' description of their feelings, such as feeling knocked-out or crushed," said Eric Ryden, a doctor of clinical psychology and therapist at Couples Therapy clinic in England. "Heartbreak seems to involve some of the same neural mechanisms as that of physical pain," he told Live Science.

The sympathetic and parasympathetic nervous systems, which usually counterbalance one another, may both be activated during heartbreak, Lee said. The sympathetic nervous system is responsible for the body’s fight or flight response, speeding up heart rate and breathing, while the parasympathetic nervous system is responsible for the body at rest, according to the Mayo Clinic Neurology Board Review (Oxford University Press, 2021). Hormones released during heartbreak activate these two parts of the nervous system, Lee said. 

"The brain and the heart, which respond to these pathways, are confused as they are getting mixed messages," she said. "This can result in disturbance to the electrical activity of the heart, with lower heart rate variability. This is evidenced by the fact that widows and widowers have a 41% increased risk of dying in the first six months after losing a spouse, according to research in [the journal] Psychoneuroendocrinology." Often people with low heart rate variability will also exhibit symptoms like fatigue, anxiety, depression and poor sleep, and heart rate variability can be used to judge clinical state in depressed patients, according to a 2019 paper in Frontiers in Psychiatry

Broken heart syndrome

In rare cases, the feeling of a broken heart can be a medical condition known as takotsubo cardiomyopathy — or broken heart syndrome. According to the Mayo Clinic, this heart condition is brought on by high levels of stress or extreme emotions, as well as surgery or sometimes physical illness. It causes temporary changes to the way the heart pumps blood and sometimes causes the heart to pump harder, which is often experienced as chest pain.

An evolutionary trait?

While heartbreak can be devastating, romantically bonding — and the pain people experience when these bonds are broken — may be a trait that humans have evolved to help them survive, Ryden said. 

"There is a large literature on the importance for survival of social bonding and secure attachment," he said. “The risk and effects of heartbreak can be thought of as part of a motivational drive towards finding a secure attachment with a romantic partner."

Lou Mudge
Health Writer

Lou Mudge is a health writer based in Bath, United Kingdom for Future PLC. She holds an undergraduate degree in creative writing from Bath Spa University, and her work has appeared in Live Science, Tom's Guide, Fit & Well, Coach, T3, and Tech Radar, among others. She regularly writes about health and fitness-related topics such as air quality, gut health, diet and nutrition and the impacts these things have on our lives. 

She has worked for the University of Bath on a chemistry research project and produced a short book in collaboration with the department of education at Bath Spa University.