What Are the Key Chemicals in Sexual Health?
HORMONES
What are hormones and how do they influence sexual health?
Hormones are the body’s chemical messengers that travel through the bloodstream to deliver instructions to cells all over the body. They are produced by different glands in the body such as the ovaries, testes, and adrenal glands and are involved in regulating sleep, mood, appetite, and sexual functioning.
Hormones are a key part of overall sexual health. This blog will explore how these chemical messengers are essential in sexual desire, physical arousal, and orgasm.
Which hormones play the biggest role in sexual desire and arousal?
Testosterone is a sex hormone in both male and female bodies. In all bodies, testosterone is the primary biological fuel for the experience of spontaneous sexual desire. When testosterone declines due to ageing, stress, medical conditions, or medications individuals may experience a noticeable dip in spontaneous desire and diminished orgasmic intensity.
In female bodies, testosterone is the most abundant active sex hormone and is produced by the ovaries and the adrenal glands. Testosterone heightens genital sensitivity and the brains receptivity to sexual cues, leading to higher arousability.
In males testosterone is produced mainly in the testes and a small portion in the adrenal glands. Testosterone manages the enzymes that control penile blood flow, meaning that testosterone is essential for erections. Overall males produce more testosterone than females.
Where is it produced:
- In male bodies it is produced mainly in the testes (95%), and a small amount in the adrenal glands (5%)
- In female bodies it is produced in the ovaries (25%) and adrenal glands (25%). The remaining is converted testosterone in body fat (50%)
Where is it sent:
- Testosterone is sent through the bloodstream to the brain. In the brain it stimulates the neurotransmitter dopamine (read more about this further down)
- Testosterone also is sent to the genitals to regulate the tissues in the penis for erectile capacity, and maintains tissue sensitivity in the clitoris and labia (the “lips” of the vulva)
Estrogen is needed in both male and female bodies, however tends to play a more significant role in the sexual health of females. In female bodies, estrogen maintains the health of the tissues of the vulva, vagina, and clitoris. It allows these tissues to be thick and elastic, for enjoyable sexual activity. Estrogen also facilitates the blood flow required for arousal, leading to vaginal lubrication. Estrogen can have a mood-mellowing effect that creates receptivity to sexual intimacy. When estrogen declines for females due to perimenopause, menopause or certain birth control methods, there can be vaginal thinning or dryness, diminished lubrication, and a reduced sense of arousability.
For male bodies, estrogen is produced when testosterone converts to estrogen which then plays a fundamental role in brain activity which also influence sexual behaviour, arousal, and desire. However, while in the brain, estrogen promotes sexual responsiveness, high levels circulating through the body significantly diminishes testosterone which in turn inhibits sexual responsiveness.
Where is it produced:
- In female bodies estrogen is produced primarily by the ovaries, small amounts are produced in the adrenal glands and in fat tissues
- In male bodies, very small amounts are secreted by the testes and adrenal glands, but the majority is converted estrogen in various tissues throughout the body
Where it gets sent:
- In female bodies estrogen is directed to the pelvis to maintain the health of vaginal and vulvar tissues
- In both females and males, estrogen acts inside the brain to stimulate neural circuits involved in sexual responsiveness. In the male body, estrogen is not sent to the brain, rather it is testosterone that is converted to estrogen in the brain (although a significant portion in the male brain remains as testosterone)
Progesterone is a natural relaxant and has an inhibitory effect on sexual responsiveness, reducing spontaneous desire. In female bodies, progesterone is involved in the menstrual cycle, preparing the uterus for potential pregnancy. During menopause, a rapid drop in progesterone can lead to mood disruptions and insomnia. In males, progesterone is minimal, and its activity is suppressed by circulating testosterone. However, it plays a role in sperm motility, regulating how fast sperm moves.
Where is it produced:
- In female bodies progesterone is primarily produced in the ovary immediately after an egg is released during ovulation
- In male bodies progesterone is produced in very small amounts in the adrenal glands
Where it gets sent:
- In female bodies progesterone is sent to the uterus in preparation for a potential pregnancy
- In male bodies progesterone is sent to the testes and supports sperm motility
- In male and female bodies it acts on the brain as a natural relaxant and mood calmer
Oxytocin is the bonding and orgasm hormone facilitating connection, trust, and empathy in both male and female bodies. During physical touch in sexual intimacy, oxytocin levels rise with a massive surge at orgasm. This surge of oxytocin triggers orgasm, the rhythmic muscle contractions of the pelvic floor in release of sexual tension. In partnered sex this facilitates a sense of post-sex attachment and calm.
Where is it produced:
- Oxytocin is produced in the brain, from there it is sent to the posterior pituitary gland where it is stored and is released in bursts into the bloodstream
Where it gets sent:
- In the brain oxytocin generates feelings of trust, empathy, and connection
- In the body oxytocin is sent to the pelvic region
Prolactin spikes during and after orgasm for both male and female bodies. This is a satisfaction hormone, and when it is released, it acts as a sexual “off” switch, in the sense that it offers deep relaxation and contentment. It is the surge or prolactin in male bodies that drives the refractory period, between erections. The release of prolactin is up to 400% higher in partnered sex, rather than solo masturbation. This suggests that orgasm with a partner provides a deeper level of both physical and mental satisfaction than solo activity.
It is also important to recognise that prolactin does not act in female bodies as an off-switch in the same way as it does in male bodies. For example, females do not have a refractory period and have the capacity to experience multiple orgasms. There is also a very small percentage of men who do not experience a refractory period due to an absence of prolactin, and are also capable of multiple orgasms.
As prolactin is an off switch for sexual responsiveness, when it remains high apart from sexual activity and orgasm, it can be a strong inhibitor on sexual responsiveness. Prolactin can be high due to natural factors such as breastfeeding, but also certain medications such as antipsychotics or SSRIs.
Where is it produced:
- Prolactin is produced at the base of the brain in the anterior pituitary gland
Where it gets sent:
-It is released into the bloodstream in a massive surge following orgasm, it is then sent back to the brain and acts as a sexual “off-switch”
- In female bodies prolactin is sent to breast tissue to stimulate milk production
NEUROTRANSMITTERS
What are neurotransmitters and how do they influence sexual health?
Neurotransmitters are also chemical messengers, however they are specific to the nervous system and brain. They do not travel through the blood but are released from one nerve ending directly to the very next nerve ending. These messages are instantaneous and responsible for split-second changes or actions such as pulling your hand away from a stove, or an increase in heartbeat due to sexual excitement.
A helpful metaphor is thinking of hormones as a mail delivery service where the message is posted out and must travel throughout the body to get to its destination. Whereas a neurotransmitter is like passing a note directly to a person next to you.
What are the main neurotransmitters in sexual health?
Dopamine is the brain’s ultimate motivation driver. Dopamine is a wanting chemical, and when it comes to sex it is involved in the anticipation of and drive to seek out sexual activity. Dopamine increases during sexual stimulation and continues to steadily increase until orgasm. Difficulties in the brain’s dopamine system can also impact on sexual desire, leading to lessened sexual desire, or more urgently seeking out sexual activity in an attempt to increase and regulate dopamine.
Where is it produced:
- Dopamine is produced deep in the midbrain and is sent straight to the emotional and reward centres of the brain
Serotonin regulates mood and happiness, offering feelings of contentment. Serotonin spikes after orgasm contributing to a sense of satisfaction. Serotonin contributes to the refractory period in males.
In this way, serotonin is inhibitory to sexual responsiveness, which can be a challenge if there are high levels of serotonin outside of orgasm. As a satiety signals it hits the brakes for arousal, suppressing blood flow, and delaying or even blocking orgasm and ejaculation. This is the SSRI dilemma (the antidepressant: Selective Serotonin Reuptake Inhibitor) as it artificially keeps serotonin levels high in the brain, which can contribute to low spontaneous desire, arousal issues, erectile difficulty, and inability or delayed orgasm in 30-60% of individuals. Conversely, it is used as a treatment to premature ejaculation.
Where is it produced:
- Serotonin is produced in the brain stem. It is sent to higher brain regions, and also downward through the spinal cord to the pelvic region.
Nitric Oxide (NO) is the most critical neurotransmitter for blood flow in genital arousal in both males and females. NO is released during sexual stimulation and opens the floodgates of arousal, by activating a secondary messenger cGMP. cGMP relaxes smooth muscle in the pelvis which allows arterial blood to flood the spongy genital tissue, causing firm erection in penises, and clitoral swelling, vaginal elongation, and vaginal lubrication.
This process is the direct target of erectile dysfunction medications which are PDE-5 inhibitors. PDE-5 is an enzyme that breaks down cGMP. If there is not enough cGMP available, there is insufficient blood flow to the penis. Therefore, PDE-5 inhibitors (e.g. Viagra), block PDE-5, to allow the sufficient action and build-up of cGMP needed for erection.
Where is it produced:
- Nitric oxide is produced directly in the pelvis by the nerve endings in the genitals, and the delicate cells of the pelvic blood vessels
Noradrenaline (Norepinephrine) is an emergency hormone and neurotransmitter. On one hand it acts as a sexual accelerator in the brain adding to sexual excitement, but on the other hand it can be a massive brake on arousal in the genitals.
In the brain, noradrenaline adds mental excitement, increased alertness, and signals sexual arousal in the heart and skin.
However, if noradrenaline is released in response to anxiety (especially performance anxiety) it acts in the body’s shut down system which draws blood away from external body parts, prioritising vital survival organs. In the genitals this causes smooth muscles in the penis and clitoral tissue to violently shut and force blood out of the pelvis. This results in a sudden loss of erection in a penis, and the loss of vaginal lubrication and pleasurable clitoral swelling.
Where is it produced:
- Noradrenaline is produced in the brainstem, and adrenal glands. In the brainstem it acts as a neurotransmitter to the brain and through the spinal cord. From the adrenal glands it floods the bloodstream acting like a hormone.
How Do These Chemicals Fit into the Bigger Picture of Sexual Health?
While these hormones and neurotransmitters play a powerful role in sexual functioning, they do not operate in isolation. Sexual health is not simply a chemical process to be “fixed” or optimised.
These biological systems are constantly interacting with psychological, relational, and contextual factors. This is what we refer to as the biopsychosocial nature of sexuality.
For example:
- You may have healthy testosterone levels, but if you are experiencing chronic stress, anxiety, or relationship conflict, desire may still feel low.
- You may have the biological capacity for arousal, but if there is fear, shame, or pressure present, the brain can inhibit the very processes needed for arousal and orgasm.
- You may experience strong emotional connection and safety with a partner, which enhances oxytocin and dopamine activity, supporting both desire and satisfaction.
- You may have the presence of specific hormones, but experience more responsive desire (read more in this blog post here)
- Your body may experience the automatic reflex of physical arousal, but your mind may not be into it, and vice versa
In this way, the body, mind, and relationship are constantly influencing one another.
Focusing only on hormones or brain chemicals can sometimes create the illusion that sexual difficulties are purely biological. They are important; however, they must be considered in the context of a much broader system of factors. It is also essential to recognise that everybody, every individual is unique in the interplay of their biology, psychology and relationships. While these chemicals do generally have a specific role and function, how this plays out in individual to individual can lead to different experiences and outcomes.
How Sex Therapy Can Help
Sex therapy provides a space to understand how these biological processes interact with your thoughts, emotions, experiences, and relationships.
Rather than focusing only on “fixing” the body, sex therapy helps you:
understand what may be supporting or inhibiting your sexual response
reduce anxiety, pressure, and unhelpful beliefs
reconnect with sensation, pleasure, and your body
improve communication and intimacy within your relationship
For some individuals, medical support may be an important part of treatment. However, addressing the psychological and relational components alongside the biological often leads to more meaningful and lasting change.
I offer online sex therapy across Australia, providing a confidential and supportive space to explore your sexual wellbeing, understand what is happening in your body, and move toward a more connected and satisfying experience of sexuality.
Final Thoughts
Sexual health is not determined by a single hormone or chemical. It is a dynamic, interconnected system shaped by your body, your mind, your relationships, and your life context.
At the same time, understanding the biology can be empowering by making sense of your multifaceted experience. True sexual wellbeing comes from integrating the biological with the psychological, and relational with self-awareness, compassion, and connection.
Written by Justine
References
Rowland DL. Neurobiology of sexual response in men and women. CNS Spectr. 2006;11(8 Suppl 9):6-12
Lambert D, Quicke J. Female Arousal and Orgasm: Anatomy, Physiology, Behaviour and Evolution. Singapore: Bentham Science Publishers Pte. Ltd.; 2023.
Kleinplatz PJ, editor. New Directions in Sex Therapy: Innovations and Alternatives. 3rd ed. New York, NY: Routledge; 2025.
Gunasekaran K, Khan SD, editors. Sexual Medicine: Principles and Practice. Singapore: Springer Nature; 2019.
Carson CC 3rd, Kirby RS, Goldstein I, Wyllie MG, editors. Textbook of Erectile Dysfunction. 2nd ed. New York, NY: Informa Healthcare USA, Inc.; 2009.
