The Biology of Codependency: How Hormones Shape Your Bonds
- Updated: February 20, 2025
Our hormones play a crucial role in life. From maintaining a calm mood to our physical well-being. Surprisingly, they also influence our decisions, which include our relationships.
As a healing and leadership coach, I am obsessed with understanding the science behind our decisions. It helps answer the question of, “If it doesn’t make sense logically, why are we doing it?”
In this article, we’ll talk about how hormones affect our ability to end bad relationships. We’ll explain why sometimes we struggle to leave even when we know it’s not good for us. This is different from another article I wrote about romantic codependency, where I discuss the causes and signs.
Firstly, we need to define some terms. We are going to talk about neurotransmitters and hormones and how they affect your thinking.
Neurotransmitters: How the Brain Speaks to Us
Have you ever felt like moving your hand away quickly when you got close to a flame, because you were afraid you might get burned? Or felt a shivery feeling in your back when you talked about a new project?
Your body has a natural reaction to these things, and it has to do with the chemicals in your brain that help your body work. These chemicals are called neurotransmitters.
Neurotransmitters are chemical substances that send signals in the nervous system, allowing communication between nerve cells or neurons. Let’s dive more into how they work.
Neurotransmitters: Your Speedy Chemical Messengers
These chemical messengers send messages from neuron to neuron, back to your brain, and based on what is happening, your brain jumps into action. And it works fast! Non-pain reactions can travel as fast as 70-120 meters per second (m/s) (156-270 miles per hour [mph]), while pain receptors travel at speeds ranging from 0.5-2 m/s (1.1-4.4 mph).
Let’s say it another way. Imagine your nervous system as a messaging system in a city. Non-pain reactions are like express messages that zip through the city at speeds of 70-120 meters per second, equivalent to the fast lanes on a highway. On the other hand, pain receptors are like slower messages taking side streets, moving at speeds of 0.5-2 meters per second. So, it’s like having two types of messages in your city – the quick ones for non-pain reactions and the slower ones for pain signals.
In addition to alerting you to potential situations (painful or not), neurotransmitters can also impact feelings, emotions, and overall mental state.
Neurotransmitters vs Hormones – Similar, Yet Different
Often times, we think that neurotransmitters are hormones, but that’s not quite accurate. The table below compares and contrasts hormones from neurotransmitters.
| What it does | What it doesn’t do | |
|---|---|---|
| Neurotransmitters | Neurotransmitters transmit information quickly between nerve cells using electrical impulses. | Cannot move through blood or control body processes like growth, reproduction, and handling stress. |
| Hormones | Hormones are chemicals that help control different body functions, like growth, digestion, reproduction and how we handle stress. | Cannot quickly communicate with the nervous system. |
Neurotransmitters and hormones have different jobs but sometimes they do similar things. For example, some neurotransmitters can also act like hormones when our body goes into “fight or flight” mode.
Hormones can also affect how neurotransmitters work in our brain. Sometimes, hormones can influence our behavior in ways that are not intelligent and may pose a risk. In the following section, we will discuss how certain hormones, when elevated, can be harmful to our bodies.
Riding the Roller Coaster of Toxic Love: How Stress Hormones Drive Destructive Relationships
Think about going to an amusement park and going on a roller coaster ride. You know it is going to involve an element of surprise, shock, and excitement. There is also risk. You also know there is a risk of riding on an apparatus that can break down or, in some cases, kill you or your baby if you are pregnant.
The same theme occurs goes in destructive, pain-filled relationships. You know that the person you are involved with has maladaptive tendencies. Also, you know they only care about themselves, but you enjoy the excitement of being with a reckless person.
You aren’t to blame – stress hormones such as cortisol and norepinephrine can play a significant role in the dynamics of painful relationships, serving both as catalysts and consequences. They get you revved up and ready to go. You may become addicted to the adrenaline rush produced by stress-related chemicals like cortisol, but these hormones can and will kill you in high doses.
When Stress Doesn't Stop: How Too Much Cortisol Hurts Your Body
I remember a client who told me she hated the fights but loved the makeup sex.
I couldn’t help but wonder how all those bouts of rage were hurting her mind and body. Our bodies release hormones to help us fight attacks and prepare for battle, but they were never designed to pump through our bodies for long periods of time.
Cortisol, a hormone essential in small acute doses for heightening heart rate, sharpening our senses, and increasing physical strength when facing potential threats, can be detrimental when its levels are chronically elevated.
Prolonged exposure to stress can will result in a range of physical and mental health issues, including anxiety, depression, digestive disturbances, headaches, muscle tension, heart disease, high blood pressure, stroke, sleep disturbances, weight gain, and impaired concentration. But like a crack addict to a pipe, some of us are absolutely hooked on cortisol.
In the next section, we’ll discuss specific neurotransmitters that act as hormones, making us do the most inexplicable things in the name of “love,” or rather, fear of being abandoned and rejected.
Emotion-Inducing Hormones
Back when I was younger—around 12 or 13—I used to read a lot of romance novels. I’d see images of damsels in distress being whisked away and saved by handsome, charming, and brave men. Little did I know, these tales flooded my body with hormones, keeping me in a fantasy world that prevented me from forming emotional connections with anyone, including myself.
Next, let’s discuss oxytocin and other hormones that can keep us infatuated and longing for someone.
Oxytocin: The Love Hormone
Oxytocin, often referred to as the “love hormone”, is responsible for bonding and attachment in relationships. Elevated levels of oxytocin can lead to attachment to an abusive or toxic partner and impact our perception of trust and safety in a relationship, even when it is harmful.
Dr. Pat Allen, a former child and family therapist, is well-known for her statement, “As soon as a man puts his penis into your mouth, anus, or vagina, you’re hooked.” Although it is crude, it is a fact.
Looking back to my single years, which were often painful, I remember my expectations for giving and receiving love in romantic relationships with men. These relationships should never have begun. Due to a lack of communication and premature intimacy, I remained in emotionally harmful relationships for an extended period.
The 3 year emotional prison sentence
Ladies – have you ever wondered why it takes years to stop having romantic feelings for a man even after only dating for a few months? The reason is that when a penis penetrates our bodies, it creates the production of the bonding chemical, oxytocin, causing us to become attached to men who may or may not treat us well. And this chemical bond can last for up to three years.
The duration of three years makes sense because our bodies were designed to mate and help rear the young. It takes about 3 years for a child’s mirror neurons to fully develop. This is nature’s way of trying to make sure a family unit is present.
Nature doesn’t care if you are in a bad relationship or not; it wants you to have babies. I cannot tell you how many “entanglements” I stayed in for years because of this chemical bond.
Dopamine and the Pleasure-Seeking Brain
Dopamine links to pleasure and reward and is known as the “feel-good” neurotransmitter.
Anticipating pleasurable moments with a partner can lead to addictive behavior in painful relationships, and this has been associated with the neuroscience behind the “on-again, off-again” cycle in toxic relationships.
When we focus on the good things while ignoring obvious relationship problems, we experience cognitive dissonance, trying to deny the reality our relationship. All the brain wants to do is reinforce those positive thoughts that keep us in a blissful state of denial.
Serotonin and Obsessive Thoughts
Serotonin is known for its role in regulating mood and obsessive-compulsive behaviors. Low serotonin levels can lead to obsessive thoughts about a toxic partner. It is challenging to break free from a relationship when obsessed with an partner is in high gear.
The best way to explain how serotonin can go haywire is through a pop culture reference. In the 1987 movie “Fatal Attraction” starring Glenn Close and Michael Douglas, Close plays a jilted lover from an extramarital affair who exhibits psychotic behaviors. In one particularly memorable scene, she boils up Dan Gallagher’s (played by Douglas) family pet rabbit.
Understanding Endorphins: Numbing Pain and Complicating Healing
It might sound strange, but when your body releases endorphins in response to pain, it can sometimes make you feel emotionally stronger.
Endorphins are natural painkillers produced by your body when you’re stressed or in pain. They activate the brain’s pleasure centers, easing physical discomfort and replacing it with feelings of happiness and satisfaction.
For people dealing with constant stress or trauma, endorphins offer temporary relief from intense emotions. However, in abusive relationships, this can create a harmful pattern. The rush of endorphins during or after physical violence can make it harder for victims to leave, trapping them in a cycle of abuse and trauma.
Almost dying for attention
I remember a distressing incident where a woman returned to her husband after he had inflicted severe injuries on her, which required hospital treatment. She declined to press charges, claiming that his actions were not his fault and were due to “job-related stress.”
One cannot help but wonder about the endorphin-induced high she experienced while enduring her husband’s violent assault, even to the point of losing consciousness.
The image below is a summary of the hormones we discussed. In the next section, we will discuss how you can heal from the hormone effects of being in a pain-filled relationship.
How to Heal from the Hormonal Effects of a Painful Relationship
Healing from a painful relationship isn’t just about moving on—it’s about helping your body and mind reset. Stress, heartbreak, and toxic patterns can take a real toll on your hormones, making it harder to feel balanced and at peace. If you’re in the middle of a difficult relationship or trying to break free, here are some things that can help you regain your emotional and physical well-being.
1. Find Creative Outlets
Art, music, and writing aren’t just hobbies—they’re powerful tools to help your nervous system calm down. Try painting, journaling, or even learning to play an instrument. Engaging in creativity allows your brain to experience pleasure in a way that isn’t tied to stress or conflict.
2. Cut Out the Drama
You can’t expect your body to heal if you keep feeding it stress. That means it’s time to step away from chaotic TV shows, gossip, or anything else that keeps your nervous system on edge. Highly dramatic or suspenseful entertainment trains your brain to stay in a cycle of tension, reinforcing the idea that chaos is normal. Give yourself permission to embrace peace instead.
3. Eat with Intention
What you eat affects your mood, energy, and even how you process trauma. Instead of eating mindlessly, slow down. Choose foods that nourish you and take the time to actually enjoy each bite. Your body needs the right fuel to recover from emotional stress, so be mindful of what you’re putting into it.
4. Seek Support
Healing doesn’t happen in isolation. Working with a therapist or trauma-informed coach can help you process emotions, break patterns, and move forward in a healthy way. You don’t have to do this alone.
By taking these steps, you’re giving your body and mind the space they need to heal. The image below sums up these tips. Up next, I’ll share my final thoughts.
Final Thoughts
For some of you reading this, you can’t ignore the fact that your behavior is influenced by chemical messages surging through your brain. So, this isn’t simply about saying positive affirmations and listening to uplifting songs. You need help to break through patterns that began in your childhood.
I hope the solutions I’ve outlined above start you on the path to healing and recovery. Most importantly, don’t go through this journey alone. You may find yourself returning to toxic relationships, driven by fantasies that “this time will be different” or by believing your partner’s lies once again. Don’t fall into that trap. Leave now.
Question: Have you experienced a painful romantic relationship? If so, what happened? You’re invited to share your story using this link. Your experience could offer insight and encouragement to someone going through a similar situation.
And if you need me, don’t hesitate to contact me. And if you want to delve deeper about building a healthy and meaningful relationship, click here to listen to this episode from my podcast or press the play button below.
