Whether you’re working on forgiving yourself or others, forgiveness is imperative for mental and physical health.

Medically Reviewed by Allison Young, MD

Holding onto wrongdoings can affect your cardiovascular system, your brain, and your immune health — and may contribute to chronic health problems, research shows.Victor Torres/Stocksy

Reaching a place where you’re able to forgive someone — whether that be another person or yourself — can be extremely difficult. But the toll not doing so takes on your body makes being able to forgive a very important skill to have.

According to Everett L. Worthington Jr., PhD, Commonwealth Professor Emeritus at Virginia Commonwealth University in Richmond, whose psychology research has focused on forgiveness, the way people reach a state of true forgiveness differs, but usually falls into two categories: decisional forgiveness and emotional forgiveness. 

“You can experience a change in your emotion, and then decide to forgive, or you can decide to forgive first and experience those changes emotionally later on,” Dr. Worthington says.

Because our relationships are so crucial to health, being able to forgive, and communicate to others that you have forgiven them, will benefit your and their health. In this respect and in many others, Worthington says: “Mental health is directly related to physical health.”

More specifically, here are three big, evidence-backed ways that forgiveness (or the act of not forgiving) affects our health.

1. Forgiveness Helps You Manage Stress

Not being able to forgive fosters feelings of anger, hostility, and stress, which are well documented to impact mental and physical health, past research shows.

A study published in April 2016 in the journal Annals of Behavioral Medicine included more than 330 people ages 16 to 79. The researchers found that regardless of age, people who were able to forgive experienced a decrease in their perception of their own stress. And this decrease led to a decrease in psychological distress.

“Although forgiveness is not the only strategy available for coping with adversity, according to this model of forgiveness, it is one of the more effective responses for reducing stress perceptions and enhancing health,” the study authors noted.

Conversely, stress — and particularly the stress hormone cortisol — has several negative effects on systems throughout the body. Chronically elevated cortisol can shrink the size of portions of your brain including the hippocampus, which is responsible for turning experiences into memories, Worthington says. It's because of this stress-cortisol link that not being able to forgive and let go of certain stresses could potentially affect memory, he adds.

In a study published in October 2018 in the journal Neurology, researchers investigated whether blood cortisol levels affected memory in more than 2,200 healthy middle-aged people. For the study, researchers measured blood cortisol levels, and compared it with participants’ scores on memory and visual perception tests, and gray matter levels in the brain as measured by brain scans (gray matter helps the brain process information). They found that people, especially women, who had high cortisol levels over time had poorer memory and performed worse on cognitive tests. Over time, they also appeared to have less gray matter in some parts of the brain.

Cortisol wreaks havoc elsewhere in the body, too. It affects the immune system at a cellular level, which means it can do widespread damage to all the parts of the body the immune system touches in unpredictable ways, Worthington explains. “It can disrupt everything from the sexual and reproductive system to the gastrointestinal system to your ability to fight off illness and fatigue,” says Worthington.

2. Forgiveness Activates the Parasympathetic Nervous System, Which Is Good News for Your Heart

According to Worthington, forgiveness affects the parasympathetic nervous system, too, which slows breathing and heart rate and increases digestion. It’s also known as “rest and digest” response (controlling ordinary bodily functions) — or the opposite of the stress fight-or-flight response (which prepares the body for more strenuous physical activity).

The sympathetic and parasympathetic nervous systems work together, so that your body can regulate things like blood pressure and heart rate, and function the way it should both in stressful situations and nonstressful moments. But when a person is under chronic stress — which can occur when someone is holding onto anger — the body may stay in the fight-or-flight response for too long.

“The parasympathetic nervous system is the calming part of the nervous system, so it turns off the hyperarousal of the specific areas,” says Worthington. Anything a person can do to calm themselves when carrying around a lot of stress activates the parasympathetic nervous system in this way (including practicing forgiveness), and can be helpful to the mind and body because it brings the sympathetic and parasympathetic nervous systems more in balance.

There’s research to suggest indeed these effects may be significant in terms of affecting health outcomes, like cardiovascular function.

In a meta-analysis published in the Journal of the American College of Cardiology, researchers found that anger and hostility are linked to an increased risk of heart disease, as well as worse outcomes for people who already have it.

A study published in the Journal of Behavioral Medicine examined forgiveness as a predictor of mortality, and found a statistically significant relationship. Forgiving others is associated with a decreased risk for all-cause mortality, the study authors noted.

3. Forgiveness Helps Your Ruminate Less (Which Can Help Lower Risk of Psychological Disorders)

According to Worthington, the act of not forgiving someone or refusing to forgive someone is almost always characterized by rumination, or playing something over and over in the mind. 

“We all ruminate, but the way that we ruminate is kind of individual. Some people do it angrily, some people ruminate hopelessly or feel depressed. Others do it anxiously,” Worthington says. And if rumination becomes habitual, it can lead to psychological disorders.

“Rumination is the universal bad boy of mental health,” Worthington adds.

Depending on your brand of rumination (whether you do it in a way that breeds hopelessness, depression, anxiety, or other feelings), these invasive, repetitive thoughts can eventually cause anger disorders, obsessive-compulsive disorder (OCD), post-traumatic stress disorder (PTSD), anxiety, depression, or psychosomatic disorders, in which stress and anxiety cause physical ailments like stomach pain or migraines. 

According to a study that included more than 1,800 Black adults, published in October 2019 in the Journal of the American Heart Association, Black women were more likely than Black men to experience more stressful life events and engage in rumination, which causes a sustained increase in hypertension over the 13 years the individuals were followed for the study. 

“When people are able to forgive, they still ruminate to some degree, but they are able to let go of a lot of that bitterness and anger,” says Worthington. “Forgiveness doesn’t eliminate rumination, but it can reduce the toxicity of it.”

With additional reporting by Angela Haupt.