We’ve broken down some basic scientific concepts and vocabulary as they apply to personal lubricants so you can better understand what’s going on in your lube and on your body.

Osmolality – the measure of dissolved particles per unit of water in a solution or serum (sometimes referred to as the concentration). The osmolality of a lubricant is important because the epithelial skin layer or the body’s natural mucus is constantly trying to maintain homeostasis, or an equilibrium of osmolality.

  • water moves freely back and forth across cell membranes in response to the osmotic pressure being exerted by the molecules of extracellular fluids (lube) on the cell’s intracellular fluid
  • osmolality is measured in milliosmoles per kilogram of solvent, labeled as mOsm/kg
  • if a lubricant has a higher osmolality than the cells of the body it’s called hyper-osmotic, causing the body’s cells to push out water in an effort to dilute the lubricant, sometimes leading to cell death via dehydration1
  • hyper-osmotic lubes can irritate the skin, and causes the epithelial layer of skin to slough off 2, dehydrate mucus, and leave a mucous membrane more susceptible to bacterial infections or STI contraction3
  • if a lubricant has a lower osmolality than the cells of the body it’s called hypo-osmotic, and causes the cells of the body to pull water out of the lubricant. This is what happens with lotions on the skin covering most of the body
  • a perfect lubricant would be iso-osmotic, meaning it would have equal osmotic pressure, or its cells would have the same hydration levels as the cells of the body
  • iso-osmotic lubricant to most of the body’s secretion would have an osmolity of approximately 285-295 mOsm/kg4
From Smitten Kitten's Lube! Pamphlet
From Smitten Kitten’s Lube! Pamphlet

Average Osmolality of:

  • Tap Water~ 3 mOsm/kg 5
  • Slippery Stuff® Liquid ~ 26 mOsm/kg 5
  • Sliquid® Organics ~ 106 mOsm/kg 5
  • Vaginal mucus ~ 260-290 mOsm/kg 6
  • Colon Lining ~ 920 mOsm/kg2
  • Human Blood ~ 285-295 mOsm/kg
  • Human Semen ~ 260-380 mOsm/kg 6
  • Good Clean Love ~ 269 mOsm/kg 5
  • K-Y® Jelly ~ 2424 mOsm/kg 5
  • ID Glide® ~ 3429 mOsm/kg 5
  • Astroglide® ~ 6113 mOsm/kg 5
  • K-Y® Warming Jelly ~ 10,300 mOsm/kg 6

Endocrine disruptors – chemicals that interfere with the natural function and balance of the endocrine system.

  • the endocrine system consists of glands, hormones, and hormone receptors which regulate a variety of vital bodily functions

Xenoestrogens – chemicals that mimic estrogen, side effects caused by xenoestrogens are called oestrogenic effects.

  • oestrogenic effects can include sexual development problems such as feminizing of male bodies or masculinizing effects on female bodies, and changes in gene expression
  • parabens are considered xenoestrogens and have weak oestrogenic effects

pH – is the measure of a liquid’s basicity or acidity on a scale from 0-14, 0 being most acidic and 14 being most basic.

  • generally healthy bodies regulate pH naturally with a particular balance of yeasts, fungi, and bacteria combined with body secretions
  • may become imbalanced when a foreign substance (like lube, douches, or enemas) disrupts the levels of bacteria or fungi
  • imbalances in vaginal pH can lead to BV and yeast infection, or serve as a warning sign or symptom of a more serious health issue7
  • vaginal and cervical pH levels naturally fluctuate with the menstrual cycle and are affected by estrogen levels, as well as playing an important role in fertility and conception

Average pH levels:

  • Vaginal pH – 3.8-4.6 (pH can range up to 5.5 without necessarily being unhealthy)
    • During pregnancy: 4.0-4.5
    • Post menopausal: 4.5-7.5
  • Semen: 7.1 – 8.0
  • Rectal Fluid: 7.0 – 8.0
  • Urine: 4.6-8.0
  • Astroglide®: 4.0
  • Good Clean Love™: 4.8
  • ID Glide®: 5.2
  • Slippery Stuff ®Liquid: 6.8
  • Sliquid® Organics: 6.8

Humectants – substances added to lubricants to keep them moist and to slow evaporation of water, preventing the skin from cooling.

  • sometimes affect the consistency of a lubricant and can increase viscosity
  • act as preservatives in lubricants or cosmetics
  • common humectants are propylene glycol, glycerol/glycerin(e), urea, or lactic acid
  • natural/Organic humectant alternatives are honey, shea butter and jojoba oil

Surfactants – chemical compounds that lower the surface tension of a liquid.

  • used to keep lubricant ingredients from separating or from evaporating, which creates a cooling sensation on the skin

Petrochemicals – chemicals derived from petroleum, or crude oil.

  • many lubricant ingredients are petrochemicals, such as propylene glycol (a.k.a. propanediol), benzene, benzoic acid, and some surfactants
  • often indicators of hyper-osmotic lubricants8, which can dehydrate mucus and cause skin irritation5 which leaves a mucous membrane more vulnerable to BV or STIs2

Microbicides – substances that kill or reduce the infectivity of viruses or bacteria added to lubricants as preservatives or spermicides.

  • common microbicides found in lubricants are nonoxynol-9, carrageenan, cellulose sulfate, chlorhexidine gluconate, and sodium dodecyl sulfate
  • some alcohols, surfactants, phenols, and acids can also act as microbicides in lubricants
  • can cause skin irritation and epithelial cell death3
  • with regular use certain microbicides that kill lactobacilli can lead to BV or vaginal yeast infection, as well as leave mucous membranes more vulnerable to infections1,6,8

Works Cited:

1) Thomas, Pat. “Behind The Label: K-Y Jelly.” Ecologist. 24-2. http://www.theecologist.com.

2) Bakhshi, Rahul P. et al., “Hyperosmolar Sexual Lubricant Causes Epithelial Damage in the Distal Colon: Potential Implication for HIV Transmission.” The Journal of Infectious Disease. 195 (2007):703-710.  Web.

3) Abusuwaa, Raed, Deborah J. Anderson, Richard A. Cone, Timothy Hoen, Thomas R. Moench, XiXi Wong. “Vaginal microbicides: detective toxicities in vivo that paradoxically increase pathogen transmission.” BMC Infectious Diseases. 6 (2006):90. Web.

4) Ayudhya, Kunjara Na, et al., “Is Wetter BetteR? An Evaluation of Over-the-Counter Personal lubricants for Safety and Anti-HIV-1 Activity.” PLOS ONE. 7 (2012):1-14. Web.

5) Adriaens, Els et al., “Mucosal Irritation Potential of Personal Lubricants Relates to Product Osmolality as Detected by Slug Mucosal Irritation Assay,” Sexually Transmitted Diseases 35 (2008):512-516. Web.

6) Moench, Thomas R., et al. “Microbicide excipients can greatly increase susceptibility to genital herpes transmission in the mouse.” BMC infectious diseases 10.1 (2010): 331.

7) Ambrosini, A., T. Maggino, M. Milani, D. M. Paternoster, L. Tudor. “Efficacy of an acidics vaginal gel on vaginal pH and interleukin-6 levels in low-risk pregnant women: a double-blind, randomized placebo-controlled trial.” The Journal of Maternal-Fetal and Neonatal Medicine. 15 (2004):198-201. Web.

8) Wolf, L. K. “Studies raise questions about safety of personal lubricants.” Chem Eng News 90.50 (2012): 46-47.