What Are Pheromones? A Closer Look At The Science & Research
People always say that love is in the air when something amorous is happening. The palpable sexual tension seemingly goes beyond words, and perhaps for good reason. Some scientists have theorized a part of human attraction could come down to our olfactory receptors. Enter: pheromones.
What are pheromones?
"Pheromones are hormone-like chemical messengers that send information outside of the body," family medicine specialist Pouya Shafipour, M.D., explains to mbg. "[Whereas] 'typical' hormones travel in the bloodstream and serve to communicate between other cells in the body [only], pheromones send messages that affect other animals of the same species."
Pheromones are famously thought to increase sexual desire, among other subliminal effects on human behavior, says psychologist Dana McNeil, PsyD, LMFT. They "act as an agent of change" encouraging certain behaviors, she explains, though those may include survival-related behaviors like sensing predators, locating nearby food, or engaging in other protective mannerisms, in addition to potentially influencing the desire to seek out intimacy and sexual activity.
Importantly, Shafipour notes research still hasn't proved whether humans actually have pheromones and just how they might influence human sexual response. "There are many questions left to be answered about how they may affect human behavior," he says. "But in animals, the research is a little more robust and shows that pheromones may impact everything from sexual arousal and food signaling to territory markers and maternal bonds."
The theory behind how pheromones work.
Pheromones are thought to be externally secreted through urine, semen, vaginal secretions, breast milk, axillary sweat, and potentially saliva and breath. Once released into the air by one individual, these secretions can then theoretically be detected by another individual via receptors in their nasal passages, explains Shannon Chavez, PsyD, a licensed psychologist and sex therapist for personal lubricant brand K-Y.
Some animals have a well-developed vomeronasal organ located in the nasal septum. That organ is what's thought to detect pheromones secreted from other animals in proximity, according to naturopathic physician Jolene Brighten, N.D. Although pheromones are recognized through the nose, Chavez notes they may not have a detectable scent.
When a pheromone is detected by the recipient, it's believed to send a signal to the brain that can influence mood, reproduction, sexual functioning, and more. The body essentially uses this information to make sense of its environment and respond appropriately: "Pheromones play a role in the survival and evolution of the body," Chavez explains. "They trigger puberty, changes in reproductive function, and survival instincts that may be necessary for social environments where there is a threat."
There's much speculation about the impact pheromones have on human attraction, so before we dive further into the theory, we need to unpack its conclusive results so far—or lack thereof.
What the research says.
There's a lack of scientific consensus as to whether human pheromones exist at all. Despite a body of research supporting the theory, many scientists question the validity of those results based on the way the studies were conducted.
For instance, an often-cited 1971 study led by psychologist Martha McClintock infamously once posited that pheromones could sync up women's menstrual cycles if they lived in proximity together. The news quickly spread and became common knowledge before the findings were repeatedly debunked over the years with additional researchers unable to repeat McClintock's results.
Scientists have studied pheromones for years but haven't been able to scientifically validate their correlation to sexual attraction due to the complexity of human interaction, the genetic variability of odors, and the molecules themselves; the components of pheromones are notoriously tricky to isolate and empirically test in well-controlled, peer-reviewed settings.
"What makes it really difficult is that research seeks to isolate scents alone to detect a response," Brighten adds, "when in reality, it's likely several variables that cause someone's behavior to shift when they take [chemicals] in."
She also points out that not all humans have that vomeronasal organ, and even if they do have it, it’s been found to be a nonoperational organ in humans, so it wouldn't be able to detect pheromones anyway. Meanwhile, other research has found some of the most commonly cited human sex pheromones as having no effect on attractiveness or gender perceptions.
Still, other pheromone-related studies have produced intriguing results. For example, researchers are exploring the nipple secretion from the areola glands in lactating mothers since the secretion seems to reflexively stimulate nursing cues in babies once placed under their nose.
Pheromones and sexual attraction.
The theory behind the link between pheromones and sexual attraction revolves around the potential pheromones androstadienone, which men produce and are thought to sexually appeal to women, and androstenone, which is thought to signal dominance or aggressiveness.
According to McNeil, men also secrete a greater amount of a potential pheromone known as androstanol, which is thought to be present in sweat and may activate a portion of the hypothalamus. In a study of 16 heterosexual women, PET scans revealed smelling androstenol triggered specific networks in the brain involved in human reproduction and may be involved with menstrual synchrony.
Women also secrete the potential pheromones copulin and estratetraenol, which reach a peak during their ovulation cycle, McNeil explains. As reported in a study in the scientific journal Evolutionary Psychology, "sensing" a woman's fertility this way may spike men's testosterone and subsequently increase competitive behaviors like dominance and guarding. It's also been theorized that women's tears contain a chemosignal that reduces male aggression.
The role of smell.
While decades of research haven't been able to definitively prove the roles pheromones play in human attraction, it is apparent your sense of smell does matter in mate selection, so it shouldn't be overlooked, according to Rebecca Alvarez Story, M.A., sexologist and co-founder of Bloomi. "From a biological perspective, [smell] is an arousal system and contributes to sexual attraction, stimulation, and satisfaction," she says. "If an individual wants to be sexually appealing, the most direct approach is to practice good hygiene, eliminate any repulsive odors, and use alluring fragrances."
Evolutionarily speaking, it may be wise to intuitively trust what your smell is telling you since it's one of the oldest senses used for survival and for environmental interaction. A small study of 70 people indicated odor sensitivity positively correlated to sexual experience, with women reporting a higher frequency of orgasm during intercourse. Another notable study in the Journal of Personality and Social Psychology randomly assigned 96 women to sniff out different scents (a neutral smell, their partner's smell, a stranger's smell) and reported the smell of a romantic partner lowered stress while the smell of a stranger increased stress levels. It suggests smell plays a critical role in social communication but calls for further studies.
Meanwhile, in a 2021 study, anecdotal reports found women are less attracted to their partner's body odor during the dissolution of a relationship. "I have found that couples on the brink of divorce will no longer find each other's scent appealing and notice new scents in their partner that are not pleasurable, such as noticing their breath or sweat as foul," Chavez adds.
But while we know odors can alter physiological states and increase desirability, scientists still aren't sure whether pheromones, specifically, sway humans romantically in the same way they can affect animals and their reproductive physiology. This is an important consideration to note since pheromones (and the purported pheromone oils, which claim to have captured its essence) are often seen as proven fact.
Different types of pheromones.
There are thought to be four types of pheromones—releasers, primers, signalers, and modulators—that all inspire varying reactions and behaviors in our bodies:
1. Releaser pheromones
Releaser pheromones work immediately and are mainly about eliciting specific, rapid responses like attracting or being drawn to a potential mate.
2. Primer pheromones
Primer pheromones affect the recipient's physiology and affect their behavior after a period of time. It targets reproductive and developmental processes like puberty, the menstrual cycle, and pregnancy.
3. Signaler pheromones
McNeil says signaler pheromones provide information and social cues. On top of determining age and sex, it also yields a unique genetic odor print so potent that mothers can recognize their newborns by smell alone, an ability that fathers may not have. Shafipour adds scent is one of the key factors that help bond a mother and baby and may play a role in early attachment behavior.
4. Modulator pheromones
Modulator pheromones, typically found in sweat, are thought to influence the receiver neuropsychologically, with their primary impacts on the women's menstrual cycle and/or affecting the mood. Research has shown when it's placed on the upper lip, it can induce feelings of improved mood and heightened focus to the recipient.
The bottom line.
Pheromones are still being studied, and there'll be more information to come about whether they exist in humans, their exact function, and how humans may respond to them. While the exact relationship between pheromones and their ability to act as an attractant is ongoing, the part you can control is understanding arousal.
"What is often left out of these conversations is how arousal works," Brighten notes. "Not all women become spontaneously aroused, and instead they need much more than what they perceive as a hot body or good smell to get them in the mood. Companies have tried to make pheromones, but it's based on the premise that all [they] have to do is smell you and it's on."
In other words, if you're looking to use the science of pheromones to try to make yourself more sexually attractive, you may need to look elsewhere. As Brighten puts it, "Sexual desire and arousal are far more complicated in the best of ways."