The Science of Sex and Smell

Olfactophilia (also known as osmolagnia, osphresiolagnia, and ozolagnia) is a paraphilia where an individual derives sexual pleasure from smells and odours. Given the large body of research on olfaction, it is unsurprising that in some cases there should be an association with sexual behavior. The erotic focus is most likely to relate to body odors of a sexual partner, including genital odors. One of my favourite papers examining sex and smell was a 1999 paper by Alan Hirsch and Jason Gruss published in the Journal of Neurological and Orthopaedic Medicine and Surgery. As they note in the introduction to their study, sex and smell have a long association:

“Historically, certain smells have been considered aphrodisiacs, a subject of much folklore and pseudoscience. In the volcanic remnants of Pompeii, perfume jars were preserved in the chambers designed for sexual relations. Ancient Egyptians bathed with essential oils in preparation for assignations; Sumarians seduced their women with perfumes. A relationship between smell and sexual attraction is emphasized in traditional Chinese rituals, and virtually all cultures have used perfume in their marriage rites. In mythology, rose petals symbolized scent, and the word ‘deflowering’ describes the initial act of sex … Dramatic literature abounds with sly references to nasal size as symbolic of phallic size, as in the famous play Cyrano De Bergerac … Psychoanalysis has made much of these associations. Fliess, in his concept of the phallic nose, formally described an underlying link between the nose and the phallus. Jungian psychology also connects odors and sex.”

In contemporary society, perfumes for women and colognes for men are marketed aggressively because it is a multi-billion pound business and are advertised in a way that suggests sexual success for those who use such fragrances. Hirsch and Gruss argue that:

“The prominent connection between odors and sex among diverse historical periods and cultures implies a high level of evolutionary importance. Freud suggested that odors are such strong inducers of sexual feelings that repression of smell sensations is necessary to civilization. Anatomy bears out the link between smells and sex: the area of the brain through which we experience smells, the olfactory lobe, is part of the limbic system, the emotional brain, the area through which sexual thoughts and desires are derived. Brill [1932] suggests that people kiss to get their noses close together, so that they can smell each other (the Eskimo kiss). Or possibly they kiss to get their mouths together so they can taste each other since most of what we call taste is dependent upon olfaction.”

One of the research areas that I have published a couple of papers with Mark Sergeant (see ‘Further reading’ below) in is on the area of pheromones (i.e., chemical substances “produced and released into the environment by an animal, especially a mammal or an insect, affecting the behaviour or physiology of others of its species”). Pheromones are known to exist across the animal kingdom from insects to primates (possibly including humans but most robust scientific studies have shown the evidence is relatively weak, and if pheromones do exist in humans the effects are likely to be very subtle). As Hirsch and Gruss note:

“Inside the human brain, near the top of the nose is an anatomical feature that gives us reason to believe that human pheromones exist: the vomeronasal organ. Its function is unknown, but in subhuman primates, this is the area where pheromones act to increase the chance of procreation … When we exercise, we sweat through endocrine glands. But when we are embarrassed or sexually excited, we sweat through apocrine glands that release high-density steroids under the arms and around the genitalia; their role is unknown. In subhuman primates, the same apocrine glands release pheromones.”

Other research by Hirsch has shown evidence that links smell with sexual response. For instance, in one of his studies, 17% of patients that had “olfactory deficits” had developed some kind of sexual dysfunction.

In Hirsch and Gruss’ 1999 study, they examined the effects of 30 different smells on male sexual arousal of 31 American male participants (aged 18 years to over 60 years). They underwent various (question-based) smell tests and their sexual arousal was assessed experimentally by measuring penile blood flow with a penile plethysmograph. The smells comprised 24 different odourants in addition to six combination odourants. All 30 odours produced an increase in penile blood flow. They reported that:

“The combined odor of lavender and pumpkin pie had the greatest effect, increasing median penile-blood flow by 40%. Second in effectiveness was the combination of black licorice and doughnut, which increased the median penile-blood flow 31.5%. The combined odors of pumpkin pie and doughnut was third, with a 20% increase. Least stimulating was cranberry, which increased penile blood flow by 2% … Men with below normal olfaction did not differ significantly from those with normal olfaction, nor did smokers differ significantly from nonsmokers.”

The findings supported their hypothesis that positive smelling odours would increase sexual arousal, and then speculated a number of reasons why this might be the case:

“The odors could induce a Pavlovian conditioned response reminding subjects of their sexual partners or their favorite foods. Among persons raised in the United States, odors of baked goods are most apt to induce a state called olfactory-evoked recall. Possibly, odors in the current study evoked a nostalgic recall with an associated positive mood state that affected penile blood flow. Or the odors may simply be relaxing. In others studies, lavender, which increased alpha waves posteriorly, an effect associated with a relaxed state. In a condition of reduced anxiety, inhibitions may be removed and thus penile blood flow increased ... Another possibility, odors may act neurophysiologically … Nor can we rule out a generalized parasympathetic effect, increasing penile blood flow rather than specific sexual excitation…The specific odors that affected penile blood flow in our experiment were primarily food odors ... Does this support the axiom that the way to a man’s heart (and sexual affection) is through his stomach? ... We certainly cannot consider the odors in our experiment to be human pheromones, therefore we believe they acted through other pathways than do pheromones.”

Shortly after this study, Hirsch and his colleagues repeated the study on females (assessing their vaginal blood flow) and found similar effects that they reported in the International Journal of Aromatherapy. In this second study they found that the largest increases in vaginal blood flow were from candy and cucumber (13%), baby powder (13%), pumpkin pie and lavender (11%), and baby powder and chocolate (4%). Obviously there are major limitations with both of these studies (such as small sample sizes, all the odours being selected by the researchers, and blood flow being the sole measure of arousal).

Scent Essential Reads

Are Scent Preferences Universal?

Sniff Test: Research Is Unraveling The Mysteries of Smell

Odours that are sexually arousing are likely to be very specific and (in some cases) strange and/or bizarre. For instance, I published the world’s first case study of eproctophilia (sexual arousal from flatulence and a sub-type of olfactophilia) in a 2013 issue of the Archives of Sexual Behavior. I’ve also come across anecdotal evidence of other strange smells that sexually arouse people. For instance, in an article on 15 Surprising & Weird Fetishes, number 11 in the list was "air freshener" fetish:

“One Reddit user reports becoming aroused as a teenager whenever he walked into a room that uses a specific brand and scent of air freshener! After some questioning from other conclusions, he suspects that the scent has become associated with the first time he watched porn. Other users report being turned on by scents such as perfume samples that were included in ‘Playboy’ magazine.”

Some paraphilias may have an element of olfaction. For instance, antholagnia refers to individuals who are sexually aroused by flowers (and the arousal may depend on the sight and/or smell of the flowers). The Kinkly website notes (without empirical evidence to back up any of the claims made):

“People with antholagnia typically have a preference for certain flowers, just as most people are sexually aroused by certain body types. They are likely to become aroused while visiting a florist shop, a floral nursery, or a botanical garden. They may also seek out images of flowers online for sexual gratification. Most people with antholagnia learn to manage their condition and enjoy healthy sex lives. They may even use the scent of flowers during foreplay or intercourse. However, if antholagnia starts to interfere with a person’s professional or personal life, he or she may wish to seek treatment. Treatment for antholagnia may consist of cognitive or behavioral therapies, psychoanalysis, or hypnosis”

I also came across an online 2013 article (‘Scents that trigger sexual arousal’) by Susan Bratton that summarized recent research (although she based most of it from material in Daniel Amen’s 2007 book Sex On The Brain). More specifically, the article notes that:

“Current research also suggests the scent of musk closely resembles that of testosterone, the hormone that enhances healthy libido in both sexes. In scent studies at Toho University in Japan, floral and herbal essential oils were found to impact sexual arousal in the nervous system. But depending on whether you need to stimulate or relax your partner to get them in an amorous mood, you would use different scents. To stimulate the Sympathetic Nervous System use jasmine, yang-ylang, rose, patchouli, peppermint, clove and bois de rose. To relax the Parasympathetic Nervous System use sandalwood, marjoram, lemon, chamomile and bergamot … Many of these scents are also commonly found in tea such as peppermint and chamomile. Many candles are scented with rose, jasmine, patchouli, sandalwood and bergamot."

There are plenty of websites that list various scents that turn people on and a lot of these appear to be based upon the research carried out by Hirsch and his colleagues. Research into sex, smell, and olfactophilia appears to be a growing area and hopefully my own research has played a small part in stimulating research into the area.