The 5 Side Effects of Kindness

image: iStock photo

When we think of side effects the first thing that springs to mind are the side effects of drugs. But who’d have thought that kindness could have side effects too?

Well, it does! And positive ones at that.

1) Kindness Makes us Happier
When we do something kind for someone else, we feel good. On a spiritual level, many people feel that this is because it is the right thing to do and so we’re tapping into something deep and profound inside of us that says, ‘This is who I am.’

On a biochemical level, it is believed that the good feeling we get is due to elevated levels of the brain’s natural versions of morphine and heroin, which we know as endogenous opioids. They cause elevated levels of dopamine in the brain and so we get a natural high, often referred to as ‘Helper’s High’.

2) Kindness Is Good for the Heart
Acts of kindness are often accompanied by emotional warmth. Emotional warmth produces the hormone, oxytocin, in the brain and throughout the body. Of recent interest is its significant role in the cardiovascular system.

Oxytocin causes the release of a chemical called nitric oxide in blood vessels, which dilates (expands) the blood vessels. This reduces blood pressure and therefore oxytocin is known as a ‘cardioprotective’ hormone because it protects the heart (by lowering blood pressure). The key is that acts kindness can produce oxytocin and therefore kindness can be said to be cardioprotective.

3) Kindness Slows Ageing
Ageing on a biochemical level is a combination of many things, but two culprits that speed the process are Free Radicals and Inflammation, both of which result from making unhealthy lifestyle choices.

But remarkable research now shows that oxytocin (that we produce through emotional warmth) reduces levels of free radicals and inflammation in the cardiovascular system and so slows ageing at source. Incidentally these two culprits also play a major role in heart disease so this is also another reason why kindness is good for the heart.

There have also been suggestions in the scientific journals of the strong link between compassion and the activity of the vagus nerve. The vagus nerve, as well as regulating heart rate, also controls inflammation levels in the body. One study that used the Tibetan Buddhist’s ‘Loving Kindness Compassion’ meditation found that kindness and compassion did, in fact, reduce inflammation in the body, mostly likely due to its effects on the vagus nerve.

4) Kindness Improves Relationships
This is one of the most obvious points. We all know that we like people who show us kindness. This is because kindness reduces the emotional distance between two people and so we feel more ‘bonded’. It’s something that is so strong in us that it’s actually a genetic thing. We are wired for kindness.

Our evolutionary ancestors had to learn to cooperate with one another. The stronger the emotional bonds within groups, the greater were the chances of survival and so ‘kindness genes’ were etched into the human genome.

So today when we are kind to each other we feel a connection and new relationships are forged, or existing ones strengthened.

5) Kindness is Contagious
When we’re kind we inspire others to be kind and studies show that it actually creates a ripple effect that spreads outwards to our friends’ friends’ friends – to 3-degrees of separation. Just as a pebble creates waves when it is dropped in a pond, so acts of kindness ripple outwards touching others’ lives and inspiring kindness everywhere the wave goes.

A study reported than an anonymous 28-year-old person walked into a clinic and donated a kidney. It set off a ‘pay it forward’ type ripple effect where the spouses or other family members of recipients of a kidney donated one of theirs to someone else in need. The ‘domino effect’, as it was called in the New England Journal of Medicine report, spanned the length and breadth of the United States of America, where 10 people received a new kidney as a consequence of that anonymous donor.


5 side effects jacket imageReferences to all studies can be found in David R Hamilton, PhD., ‘The Five Side Effects of Kindness‘ (Hay House, February 2017).

For live online talks covering kindness, the mind-body connection, self esteem, plus life and spiritual, check out my Personal Development Club.

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  1. Sherry Knight on March 30, 2016 at 8:44 pm

    Loved this! <3 Thanks for sharing 🙂

    • David R. Hamilton PhD on April 8, 2016 at 2:51 pm

      Thanks Sherry. 🙂

  2. Nora Hopkins on February 14, 2017 at 6:08 pm

    So useful for my Project! Thank you for all your help!

    • David R. Hamilton PhD on February 16, 2017 at 10:43 am

      I’m pleased it’s helpful, Nora. 🙂

  3. skylar miller on February 14, 2017 at 7:23 pm

    This has 5 side effects, but what about the side effects of when your moody, or upset.

    • David R. Hamilton PhD on February 16, 2017 at 10:43 am

      I don’t know much about side effects of being moody or upset, Skylar. I think that’s part of our humanness so I don’t believe there are any negative consequences. I believe the body has a health-bias towards kindness so when we’re kind we help the body be healthy in a number of different ways. 🙂

  4. MN on February 28, 2017 at 1:42 am

    Very Helpful, thanks

  5. mariechelle sun on August 20, 2017 at 1:41 am

    wow my mom loved this

  6. Ruby Chan on October 5, 2017 at 10:57 pm

    Thank you immensely for your excellent teaching and for generously sharing your amazing knowledge, which have positively transformed so many people’s lives. My friends and I were incredibly impressed for your outstanding presentation on 1 October 2017, at the Hay House “I Can Do It” Event. –

    • David R. Hamilton PhD on October 16, 2017 at 9:53 am

      Thanks for your kind words, Ruby. 🙂

  7. Stephanie on October 26, 2017 at 11:24 am

    I’m feeling super blessed right now! I awoke this AM w/ an unusual & unrelenting need to post words of kindness all on FB & to also challanged (in a not so obv. way) ppl to choose kindness and not only lift others up but also reap the many physical, mental, & emotional benefits being kind has to offer to the ‘givers’ of kindness.
    Prior to hitting ‘POST’ I quickly checked the neurophys effects re:to kindness on our brains & the correct name of the biochemical released in our brains, ( I was correct, but kept second guessing myself between dopamine and serotonin). It was during my quick ‘research’ when I incidentally stumbled upon this article, and as I’m typing this comment I can’t help but to think…”it was a ‘God thing’ “. Thank You for sharing. Thank You for spreading smiles, joy, warmth & kindness; May the ripple continue! Have a Blessed day!

    I would like to say something in response to Sherry Knights question regarding the side effects of being upset or moody, while I’m not a doctor, I am a medical professional. I have been fascinated by our beautiful brains for as long as I can remember and I’m constantly reading, studing, researching…etc. all things brain… I don’t totally disagree with your answer to Sherry re:to her question about possible side effects of being moody and/or upset, but, to be clear, I do think it’s important to note that these moods, IF handled appropriately, (ie: addressed quickly & expressed in a healthy manner), ‘shouldn’t’ have neg side effects, however, when ppl don’t address these issues timely, appropriately, and in a healthy manner (ie: not addressing source of frustration, “bottling up” emotions, exploding, or ‘carrying’ “it” with you), all of which MOST DEFINITELY have negative side effects on our physical, mental, and emotional well-being, many of them.

    Just my opinion, gained through self-taught knowledge and life experiences.

    Have a great day!

  8. Lily on December 31, 2017 at 12:22 am

    Thank you for your meaningful and important work Dr. Hamilton. This type of discussion, in my opinion, is exactly what the world needs right now. When there appears to be so much polarization in our country it’s a reminder that we all need and want the same thing. Just a little Love and kindkindness can go a long way. I’m old enough to remember when it was very common to see bumper stickers that said “practice random acts of kindness”.

    • David R. Hamilton PhD on January 3, 2018 at 6:16 pm

      Thanks so much for your kind words, Lily. 🙂

  9. Jojo on January 27, 2018 at 3:59 pm

    I’m reading your book! It’s amazing to me that being kind can increase our longevity and can be a physically protective factor, not just the obvious result of strengthening relationships. Really impressed with your work! And I love Robert Holden, going to see him in May. Just love the transformative knowledge that you are both sharing!!!

    • David R. Hamilton PhD on January 30, 2018 at 12:31 pm

      Thanks for your kind words, Jojo. Your kindness made me smile. 🙂 I totally agree, re: Robert Holden. One of the best speakers I’ve ever heard. 🙂

  10. Jose I Martinez on April 2, 2018 at 9:39 pm

    Hi: I am working on a project where I would like to classify differe levels of kind people based on the “amount” of kindness based on volunteer work.

    Are there already levels of kindness? I want to be able rl label the person based on the amount of kindness provided, not so much in the quality of kindness.

    • David R. Hamilton PhD on April 6, 2018 at 8:27 am

      Hi Jose, I’m not sure if levels of kindness have been used. However, I’d recommend Allan Luks’s book, ‘The Healing Power of Doing Good’. His original research quantified the number of hours of volunteer work people did and correlated it with happiness. He surveyed over 3,000 people who did volunteer work and concluded that 95% of people reported it making them feel happier. There might be some things in his research that are useful to you. I hope that helps. 🙂

  11. Amanda on May 29, 2018 at 12:01 am

    I’m doing a project on a kindness project and its side effects on others and everyone surrounding them. Thanks, this helped so much for me and will probably stick with me for a while.

    • David R. Hamilton PhD on June 29, 2018 at 3:14 pm


  12. Virender Kumar batra on October 30, 2018 at 9:46 am

    I am glad to know that kindness can give to us health,wealth,happiness, can fulfill our dreams. thank you God, you are wonderful, very, very kind to all.

  13. proxy on December 4, 2018 at 6:27 pm

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  14. Patricia on January 6, 2019 at 2:34 am

    I stumbled across this article and after I read #1, and the feeling of a natural release of opioids, I reflected back to the other day when I didn’t know what, who or how was that? LOVE, GOD, KINDNESS, BLESSED, COMFORT. . . I was sitting in my car in a parking lot and saw this group of people putting groceries in a car. I saw all of them at one time or another separately. I realised that they were all together. With each passing of them in the store, it was obvious that money was tight and choices were being added and exchanged for other needs. I never get extra cash with my debit card but, I DID THIS TIME. No intentions at the time. Staring out at each one of them, there was a baby, a very deformed older women, one man and two other women all trying to get into there small car. I jumped out of the car and as I walked up to them they started turning around to me. The first person closest to me was the deformed women. I looked at her and placed a $20 bill in her hand and told her I want you to have this. The whole group was so appreciative and showed it to me graciously. I got in my car and drove off and I felt this overwhelming warmth of my heart like it was filling up and it felt so good that I came to tears. I thought I love this feeling of a random act of kindness and googled about the physical effects of RAOK. You explained it. Jokingly in my mind was that I do a RAOK everyday in one way or another but, that dose was stronger than I have felt in a long time and I want more. Can you accidentally overdose from it?

  15. Kevin Cheung on March 5, 2019 at 2:00 pm

    Thank you for your helpful article Dr. Hamilton. Although I have known that kindness has many benefits, but your detailed and scientific induction makes me deeply aware. Such rigorous induction is amazing!

  16. Anna on April 2, 2019 at 5:57 pm

    I believe kindness DEFINITELY leads to all these benefits. Can you please do a study on why some people react so negatively to kindness. Being kind is very important and Jesus Christ told his followers to love one another above all else. However, kind people re truly spat upon by society and taken as “manipulative” and disingenuous. Some people honestly treat kindness as if it is some kind of deadly disease, making it nearly impossible to continue being kind to them. Why is that? I truly don’t get people who HATE kind people.

  17. Katherine Littlewood on October 10, 2019 at 6:46 am

    Hi David, I was at the Fanatics event yesterday and really enjoyed hearing you speak. It was part of a great day for the company. Your words were inspiring and I learnt so much. Hoping we can all be a little bit kinder to each other today and every day. Katherine

  18. peppa on January 28, 2020 at 7:59 pm

    i think this artical was so exiting i love learning about kindness at my sons school it is kindness week…………………………………………………………………………………..

  19. Johnny on May 13, 2020 at 11:46 pm


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