Contents: 6 mg of androstenone (5-androst-16-ene-3-one) with 6 mg of vitamin E acetate as preservative in 10 ml of odour-free diluent. Directions: Apply to upper lip. One application of 3-4 drops should last for 4-5 hours. Androstenone is the best-established human pheromone. Pheromones are chemical messengers, which have profound effect in animals on hormone concentration, behaviour and mood. In humans, pheromones are now recognized as exerting changes in hormonal levels, mood and behaviour. Pheromones act through two major pathways: the vomeronasal organ, and the main olfactory epithelium.[1] The existence of the vomeronasal organ is now well established in all human beings from neonates to adults[2],[3],[4]. Androstenone appears to act through the main olfactory organ, although some action through the vomeronasal organ cannot be excluded.[5] The vomeronasal organ is connected neurally to the amygdala and hypothalamus and pheromones acting on the vomeronasal organ can change the concentration of hormones at the hypothalamic level and in turn hormone output from the pituitary  (prolactin, luteinizing hormone etc6). The main olfactory organ activates higher cortical centres changing emotion and mood, in addition to providing a parallel separate route of chemosensation to the hypothalamus[6]. Androstenone is biosynthesized from androgens - in the testes and on the surface of the skin (by microbial action). A postulated biosynthesis is: testosterone ® 4,16 androstadienone ® 5a-androst-16-ene-3-one[7] There is therefore a direct correlation between the blood concentration of testosterone and that of androstenone[8]. It is secreted by apocrine glands in specific areas of the skin. These areas are principally the axillae, nipples, pubic, genital and the circumoral region and the lips. In addition, smaller quantities are secreted by the eyelids and the outer ear[9],[10]. It is estimated that about 50% of individuals cannot smell it. For those who are able to smell it, the odour is described variously as sandalwood-like, sweaty or musky. Although nearly all children can smell it, the ability to detect androstenone disappears during adolescence in about 50% of individuals.[11] Ability to smell androstenone is also influenced by state of pregnancy and stage in the menstrual cycle. Some flushing around the nose and cheeks has been noted in individuals, when exposed to androstenone. There is therefore an observable physiological reaction from androstenone, which may be attributed to its pheromone nature. Androstenone-containing secretions have been shown to have the following effects on menstrual problems and depression and anxiety. These effects are achieved by inhalation alone and presumably are mediated through the main olfactory organ and/or vomeronasal organ. Menstrual Problems Exposure of women to androstenone and other androstenone-like compounds normalized the length of the menstrual cycle in women with unusually long or short menstrual cycles and may reduce dysmenorrhea[12]. Depression and Anxiety Androstenone is known to induce sexual attraction and set the mood for amorous behaviour. In such cases, depression and anxiety need to be dispelled. Some unpublished work has shown that mood is elevated in women, when they are exposed to androstenone.   [1] C. Dulak and R. Axel, Chem. Senses, 23, 467-475, 1998 [2] D. T. Moran, B. W. Jafek and J.C. Rowley, J Steroid Biochem Biol, 39, 545-552, 1991 [3] W. Stensaas, R. M. Lavker, L. Monti-Bloch, B. L. Grosser and D. L. Berliner, J Steroid Biochem Mol Biol, 39, 553-560, 1991 [4] J. Garcia-Velasco and M. Mondragon, J. Steroid Biochem. Molec. Biol., 39, 561-563, 1991 [5] K. M. Dorries, E. Adkins-Regan and B. P. Halpern, Brain Behav Evol, 49, 53-62, 1997 [6] S. S. Winans and F. Scalia, Science, 170, 330-332, 1970 [7] R. Claus and W. Alsing, J. Endocr. 68, 483-484, 1976 [8]E. E. Filsinger, J. J. Braun, W.C. Monte and D. E. Linder, J Comp Psych, 98, 219-22, 1984 [9]J. Hopson, Scent Signals: The Silent Language of Sex, William Morrow and Company, NY, 1979 [10] Α. Comfort, Nature, 230, 432-433, 1971 [11] L.M. Bartoshuk and G. K. Beauchamp, Annu. Rev. Psychol. 45, 419-49, 1994 [12] W. Cutler, Love Cycles: The Science of Intimacy