The science behind kissing: 10 things that happen when we kiss

Whether it’s a quick polite peck, or an awkwardly long PDA that spurs on a chorus of ‘Get a room’, there are several biological and chemical changes that happen inside us when we kiss- there is even a field of study dedicated to this – Philematology, which is the science of kissing.

People often say they can decide if there is ‘chemistry’ between you and a partner by one kiss – so here is the literal chemistry we all unknowingly refer to:

Can anyone else see the pheromones between them?
Can anyone else see the pheromones between them?

1. Kissing relieves stress:

Several studies have measured levels of the stress hormone, Cortisol, before and after a make out session, and in both men and women there is a consistent, significant drop in cortisol. So if you are stressed – have a little smooch (although if it is work related stress maybe don’t pucker up in the boardroom, that would be super awkward).

2. Kissing releases the love hormone – Oxytocin:

There is a reason Oxytocin is known as the love hormone – it is released from the pituitary gland when we engage in sexual activity. It has the effect of making us feel sexually aroused and can also makes us feel a closer bond and more trust with our partner. When we kiss our levels of Oxytocin sky rocket, so kissing does make us feel closer.

3. Men pass along their testosterone in saliva to activate women’s sex drives

An interesting theory by Helen Fisher from Rutger’s University found that there is testosterone present in men’s saliva. She also found that men preferred a more saliva filled, slobbery kiss. Her theory was that men were unconsciously passing their testosterone filled saliva on to women in an attempt to activate the part of the woman’s brain associated with sex drive. I think this idea is intriguing, it certainly makes evolutionary sense, though I’m not a fan of sloppy kisses myself!

4. All the happiness chemicals are released:

Kissing stimulates nerve endings on our lips, which sparks release of dopamine. Dopamine is a neurotransmitter that is active in circuits in the brain associated with pleasure, and it makes us feel happy. Dopamine is also associated with feeling rewarded, which can make us want to repeat a behaviour – so one kiss with someone really can lead you to wanting more of them. Endorphins are released when we kiss, these are neuropeptides that gives us a happy buzz, like after we exercise. Phenylethylamine levels also increase during a kiss, this chemical is actually similar to amphetamines, and it not only makes us happy, it has aphrodisiac effects too! Don’t worry if you don’t have a special someone to smooch, you can find phenyethylamines in chocolate!

5. Your adrenal system gets all excited

When we kiss the adrenal system releases adrenaline and noradrenaline. This puts our whole body into an excited, revved up state where our heart rate increases and sugars break down in the body to give us more energy so we are ready for action. Also, blood rushes away from the stomach to our muscles and our sexual organs, so we can be prepared for any impending…. further action….

6. You tone up your face muscles

You use about 30 muscles when you kiss (depending on the type of kiss) and repeatedly doing this can exercise these muscles in a way that tones up the muscles in your face, preventing them from drooping, so kissing can prolong your youthful looks.

7. Pheromones fly about between you

Pheromones are like hormones, but they are released outside of your body, and recognised by others of the same species. Nobody really understands them, but from what we know so far these chemicals are released when we kiss, and our partner can sense them with their nose and mouth and will be able to detect if you are aroused. This is much better documented in animals, but it is thought humans could act the same way.

8. You burn loads of calories:

Passionate kissing is said to burn 6.4 calories a minute. That means half an hour of kissing burns the same amount of calories as running for  around 25 minutes or swimming for about 30 minutes (depending on how fat or fit you are). Would you rather go to the gym or get some ‘alternative exercise’? Let me think about that one.

9. The way you tilt your head is learnt in the womb.

We have all had the awkward situation where you both lean your head one way, and then you bash heads and it’s super awkward and kills the moment. Head orientation preference in kissing is actually thought to be developed when we are a foetus, due to where our head and hands are positioned in the womb. Now there isn’t a huge amount of evidence on this, but I think the idea of it is cute. Research has found that most people do tend to tilt to the right anyway, and that when there is a clash of heads it is a real turn off! (I know you are tilting your head whilst reading this, and I know most of you are tilting to the right!)

10. Our pupils widen:

This is why we close our eyes when we kiss – it’s just creepy having big bug eyes staring at you!

So now we know that the little spark we feel in those tender moments is actually just a series of chemical reactions and our hormones flying about having a little party. It is thought however that these reactions don’t occur as strongly when the physical attraction isn’t there, so it is true that you can decide if there is real attraction and chemistry with just one kiss…

Till next time,




Mosquito bites – why some people always get bitten and a novel way to repel mossies

One thing that stands between us and a perfect summer is pesky mosquitoes buzzing around and leaving unsightly bites that you just can’t stop scratching. I seem to be one of those people who get eaten alive on holiday and have always wondered why. I had assumed that I was just really tasty, but I have now looked into the science behind why some of us are more prone to getting bitten. I also looked at how insect repellent works and a new way to repel those mossies.

Image from
Image from

Why do some people get bitten way more than others?

As I said, I always get eaten alive on holiday and it drives me absolutely mad. There are a few potential reasons as to why this is:

Genetics: If you carry genes that make you release more uric acid than others, mosquitoes will be more attracted to you. (Thanks parents for my genes… not)

Type O blood type: A study has found that mosquitoes landed on those with Type O blood nearly twice as much as those with Type A. Some of us also release a chemical out of our skin that indicates to mosquitoes what type of blood we have, which would invite the mossies onto the Type O bodies even more so.

Exercising: If you tend to exercise a lot on holiday your skin temperature will be warmer and you will secrete more lactic acid. Both hot skin and lactic acid have been found to be attract mosquitoes. (So stop jogging, get a cocktail and holiday properly!)

Breathing out more carbon dioxide: Mosquitoes are experts at detecting carbon dioxide and they use this to locate their next victim. So if you breathe out more co2, then you are more likely to have a mossie land on you. As a general rule, larger people breathe out more co2 , which may explain why you probably got bitten less as a tiny kid then you do now as an adult.

Being pregnant: This one doesn’t relate to me (thank god) but pregnant women are twice as likely to get bitten. This is thought to occur because they are warmer and exhale more carbon dioxide.

Drinking beer: Nobody is quite sure why, but drinking beer makes you much more likely to get bitten.

How does insect repellent work?

There are a vast range of products claiming to repel mosquitoes, many of these contain a chemical known as DEET. There are two ideas about how DEET works, and scientists just can’t agree on which is the most likely reason. One idea is that DEET confuses the insects by interfering with their odour receptors in their antennae. This makes it difficult for the bugs to smell and detect us. The other idea is that the insects just do not like the smell of DEET and will therefore avoid us if we are wearing repellent.

The vitamin B trick: 

A friend of mine swears by ‘the vitamin B trick’ to repel mosquitoes. It involves taking a vitamin B1 supplement every day in the week leading up to your holiday and throughout your trip. The idea is that the excess vitamin B leaks into your sweat, producing a odour that the mosquitoes dislike, so they are repelled. This may seem like an easy solution to the mosquito problem, however research on this is a bit hit and miss. I’m not sure I completely buy it, but I guess it couldn’t hurt to try it?

So there we have it, some of us are destined to be bitten, but we have a few options to help reduce the amount of bites we endure.

Fun fact: only female mosquitoes bite!

Till next time,