Did You Know…lubricants and vaginal moisturizers have similar compositions but different uses?

June 2023

First, the function of a personal lubricant is to reduce friction during sexual activity or other kinds of vaginal insertion (dilators, for example). The function of a moisturizer, on the other hand, is to increase hydration of the tissue. Although the basic formulations of these two types of products may be very similar, ingredients are added to enhance either the lubricity – ability to glide – or the moisture-carrying capacity of the product.

Lubricity is often enhanced in a water-based gel by including glycerin and glycols. These molecules have a smooth texture and are chemically safe but are required at high concentrations to achieve the desired effect. This means the final product is hyperosmotic, so that even though it is a water-based gel, it actually dehydrates the vaginal tissue. The World Health Organization recommends finding lubricants that are iso-osmotic to avoid damaging tissue¹, which can increase susceptibility to infections². Such iso-osmotic lubricants often are water-based gels using aloe, hydroxyethylcellulose (HEC) or hypromellose as thickeners, and therefore have very similar composition as a vaginal moisturizer, with the addition of extra ingredients designed to thicken the product. Regardless of the texture (a thick gel vs. a thinner liquid), lubricants must provide a good glide for an extended period of time.

The function of a personal lubricant is to reduce friction during sexual activity or other kinds of vaginal insertion (dilators, for example). The function of a moisturizer is to increase hydration of the tissue.

Lubricity is not a factor for vaginal moisturizers. For these products, the most important characteristic is that it is water-based and iso-osmotic. It may even lean slightly toward being hypo-osmotic, though going too far in that direction will cause vaginal epithelial cells to swell and even burst. Moisturizers contain ingredients that can adhere to many water molecules, such as HEC, hypromellose, and hyaluronic acid. In dry tissues, some of this water will be transferred to the tissue to hydrate the superficial layers, which enables better natural desquamation of epithelial cells, protects against damage, and improves tissue feel by increasing the turgor (plumpness) of tissues.

What about using an oil-based lubricant or moisturizer? We do not generally recommend oil-based products as a first choice. The use of oils and petroleum jelly intravaginally are associated with increased risk of Candida colonization and BV, respectively³. Oils weaken condoms, and oils from your kitchen may have gone rancid or have microbial contaminants without any obvious signs. And an oil-based product is not able to actually add moisture to tissue – only a water-based product can do that. Oil-based products, including creams, lotions, ointments, balms, etc., are good for skin because they create a barrier to prevent trans-epidermal water loss (TEWL). But TEWL is not a consideration for the vagina at all, and has only a small effect for the vulva. However, there may be a role for oil-based vulvar balms, creams, ointments, etc. because of their ability to stay in place and reduce friction on irritated tissue.

All in all, the characteristics of a good lubricant are similar to the characteristics of a good vaginal moisturizer. In fact, a moisturizer can be used as a lubricant in a pinch. And the FDA regulates vaginal moisturizers as if they were personal lubricants (Class II medical devices) due to their similarity. So it is easy to see why confusion exists. How do you help a patient select the right product? It comes down to what their need is.

For a patient who feels dry only during sex, or needs to aid in vaginal insertion of dilators, pessaries, or other devices, lubricants are the right choice. For patients experiencing dryness, malodor, or other discomfort during daily activities of life, a vaginal moisturizer is appropriate. In fact, a vaginal moisturizer – and a “placebo” gel – were shown to be just as effective as a vaginal estradiol cream at reducing vaginal dryness and pain⁴, though to achieve full benefit of restoring the vaginal microbiome, estradiol was needed⁵.

Regardless of the choice, high-quality products will be iso-osmotic, have the right pH (3.5-4.5) and contain lactic acid to support health of the vaginal microbiome.

References

1. World Health Organization. Use and Procurement of Additional Lubricants for Male and Female Condoms: WHO/UNFPA/FHI360 Advisory Note.; 2012:1-8. Accessed May 15, 2023. https://apps.who.int/iris/handle/10665/76580
2. Dezzutti CS, Brown ER, Moncla B, et al. Is wetter better? An evaluation of over-the-counter personal lubricants for safety and anti-HIV-1 activity. PloS One. 2012;7(11):e48328. doi:10.1371/journal.pone.0048328
3. Brown JM, Hess KL, Brown S, Murphy C, Waldman AL, Hezareh M. Intravaginal practices and risk of bacterial vaginosis and candidiasis infection among a cohort of women in the United States. Obstet Gynecol. 2013;121(4):773-780. doi:10.1097/AOG.0b013e31828786f8
4. Mitchell CM, Reed SD, Diem S, et al. Efficacy of Vaginal Estradiol or Vaginal Moisturizer vs Placebo for Treating Postmenopausal Vulvovaginal Symptoms: A Randomized Clinical Trial. JAMA Intern Med. 2018;178(5):681. doi:10.1001/jamainternmed.2018.0116
5. Srinivasan S, Hua X, Wu MC, et al. Impact of Topical Interventions on the Vaginal Microbiota and Metabolome in Postmenopausal Women: A Secondary Analysis of a Randomized Clinical Trial. JAMA Netw Open. 2022;5(3):e225032. doi:10.1001/jamanetworkopen.2022.5032