Why Some Lubricants Leave You High And Dry

Vagina science. It’s important.

Today’s vagina science lesson is about fluids. Specifically, what’s in the fluid — and how it behaves in said vagina.  

Take water, for example. Water isn’t really just water. There can be all sorts of particles in it: magnesium, calcium, salt or even, say, lead. The amount of dissolved particles per unit of water (or any liquid) is called osmolality. The higher concentration of particles per unit of liquid, the higher its osmolality.

Is high osmolality—or hyperosmolar—liquid bad? Well, that depends on the context, but essentially, hyperosmolar liquid has more particles in it than the liquid normally found in our bodies. Net-net: it’s not good, especially when it comes to your personal lubricant.

Why is osmolality important with lubricants? Because of osmosis. Throw yourself back to 7th-grade science class and remember that water, when faced with a semi-permeable membrane that has a more concentrated liquid on the other side, will pass through that membrane to create equilibrium on either side. Good old water. It just wants equality.

So when it comes to your personal lubricant, that semi-permeable membrane is your skin’s living cell tissue—as in, skin cells or the mucosal cells in your vagina. Along with water, your cell walls want homeostasis, or equality, too. They want the fluid inside the cell and outside the cell to have the same amount of water. But if you put a hyperosmolar lube next to a skin or mucosal cell—say, in your vagina—it’s going to wreak a little intercellular havoc. Pulse™ advisor Dr. Cindi Buxton, N.D. Lac, who helped formulate our exclusive personal lubricants, puts it into perspective: “The cells will give moisture to that fluid, diluting it to try and create equilibrium.” Which is pretty difficult, when the cell is faced with something that has tons of particles in it, and not a lot of liquid.  

Your vaginal cells are going to work overtime to give that liquid more water, dehydrating themselves in the process. How dehydrated? Well, that depends on the osmolality of the lubricant. But here’s the thing: the FDA does NOT require lubricants to publish osmolality levels on the packaging. Our suggestion? Read labels, and look for the big red flag in the list of ingredients: glycerine. If it’s one of the lube’s first three ingredients, then it’s very likely that the lube in question is hyperosmolar.

If you want to take the deep dive into the science, the ideal osmolality in a water-based personal lubricant is something that will about match what’s in our bodies. Osmolality is measured in milliosmolesone-thousandth of an osmoleper kilogram of water (mOsmol/kg). Vaginal mucous, for example, is 260-290 mOsm/kg, so you want whatever you’re putting in your body to as close as possible to that number. (The World Health Organization recommends avoiding products with osmolality greater than 1200 mOmol/kg.)

We worked hard to give our exclusive H2Oh! Water-based lubricant an iso-osmolar (or, as osmolar as liquids normally found in the intercellular tissue) makeup. Developed with Dr. Cindi, H2Oh! was designed to exist in harmony with the delicate tissue found in your nether regions. How does it rate? Let’s compare Pulse Pod lubricants to most other lubricants on the market. Some measure as high as 10,300 mOsmol/kg. On the other hand, our H2Oh! natural, water-based formula with pure hydrating chia (don’t worry, no seeds in sight) measures 301 mOsm/kg. In other words, it won't be stealing water from your vagina or your skin. (And if you’re wondering where Aloe-Ahh, our exceptional silicone lubricant formula with Aloe and Vitamin E falls on the spectrum: Unlike water-based lubricants, silicone products can’t dehydrate the water-based body tissues, so there’s no osmolality measurement necessary.

Graphic modified from Chemical and Engineering News; Pulse H2Oh! has an ideal osmolality, close in proximity to the 260-290 mOsm/kg osmolality of vaginal mucous


As we all know, a dehydrated vagina is an unhappy vagina; high-osmolality lubricants can dry out the tissues in your vagina and make them more susceptible to bacteria, yeast and viruses. Also: A dehydrated vagina is an unprotected vagina. “Recent studies have shown that when a hyperosmotic lube is put against vaginal tissue, it sucks moisture out of the cell walls,” says Dr. Cindi.  “It can cause damage to or even kill cells in the vaginal mucosa, and can really increase the risk of contracting sexually transmitted diseases and infections—including HIV.”

So, the lesson? High-osmolar liquids in your vadge does not lead to a happy, healthy body.

Class dismissed!


Laura Shinn is a Portland, Oregon-based writer and strategist covering health, wellness, food, fashion, and culture.


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