What is osmolality?

According to YES

Osmolality, a more formal definition, is the measure of dissolved particles per unit of water in a solution or plasma (also called the concentration). The osmolality of a lubricant is important because the epithelial (outer) layer of skin is constantly trying to maintain an equilibrium of osmolality (remember Osmosis from school biology lessons?) between the skin cells and the lubricant on the outside wall of that cell.

  • Osmosis is the process where water moves back and forth across cell membranes in response to the concentration of chemicals in the liquid (here we mean lubricant) on the outside of the cell. Osmosis tries to balance the concentration on both sides.
  • When a lubricant has a higher osmolality than human cells or bodily fluids (like blood) it is called hyper-osmotic. When tissues are in contact with a hyper-osmotic lubricant they try to dilute the lubricant by releasing water. This can cause the cell to die as it becomes super concentrated and no longer able to function. The net result is the layer of cells break down and the body’s barrier to infection is compromised.
  • So hyper-osmotic lubricants can irritate the skin, cause the barrier layer of skin to be damaged and dehydrated and leave a mucous membrane (anal or vaginal) more susceptible to bacterial infections or STI contraction.
  • When a lubricant has a lower osmolality than human cells or bodily fluids (like blood) it is called hypo-osmotic. When tissues are in contact with a hypo-osmotic lubricant they try to pull water from the lubricant into the cell. This means that a slightly hypo-osmotic lubricant would rehydrate dry tissues, but an extremely hypo-osmotic lubricant could cause these cells to burst.

Therefore in our view:

  • A perfect vaginal moisturiser’s osmolality would be iso-osmotic, meaning it would have identical osmotic pressure, to vaginal tissues as it can be present in the vagina for extended periods, like 1-2 days, and will release water as needed.
  • A perfect vaginal lubricant’s osmolality would be hypo to iso-osmotic, meaning it would have similar osmotic pressure, or its concentration would be similar, to the tissues to which it is applied.
  • A perfect anal lubricant’s osmolality would be iso-osmotic, meaning it would have identical osmotic pressure, or its concentration would be identical, to the tissues to which it is applied.
  • An ideal iso-osmotic lubricant, to most human tissues, would have an osmolality of 270-310 mOsm/kg as this encompasses the osmolality of human plasma.
  • A perfect sperm friendly lubricant’s osmolality would be iso-osmotic with semen, which is slightly higher than typical human tissues.

Water vs Oil

Water-based lubricant


  • A unique dual purpose vaginal moisturiser and lubricant. For topical use to relieve discomfort or as a sexual lubricant.
  • Formulated from water-retaining plant polymers to rehydrate delicate tissues.
  • pH balanced to maintain the typical vaginal environment and combat thrush & irritation.
  • Provides intensely realistic lubrication.
  • Highly effective in treating the symptoms of vaginal dryness.
  • Compatible with natural rubber, latex and polyisoprene condoms and toys.
Plant-oil based lubricant


  • Strong, long lasting lubricants, giving additional protection for dry and sensitive tissues.
  • Natural alternatives to synthetic chemical lubricants such as silicone or petroleum-based products like Vaseline.
  • Also suitable for use as an intimate massage oil or all over the body
  • For exceptional skin conditioning YES OB contains:
    • In tubes: sweet almond oil, Shea butter, cocoa butter and vitamin E
    • In 5ml applicators: Coconut oil, Jojoba oil, Grapeseed oil and vitamin E
  • Can protect and feed dry intimate tissues. Will not, however, rehydrate tissues as does not contain water.
  • NOT condom compatible.

Why organic ingredients?

By working with nature and avoiding pesticides, chemical fertilisers and genetic engineering, Organic production promotes the health of the soil, plants, animals and us in the following ways:

The Quality

The improved quality of organically produced crops and therefore of our ingredients

  • No growth hormones, chemical fertilizers or damaging pesticides are used
  • No genetic engineering

The Health Benefits

The health benefits associated with using pure ingredients

  • No synthetic chemicals present to be absorbed by the skin
  • 60% of all chemicals put on the skin end up in the blood stream

The Standards

The rigorous standards for certification

  • No compromise on ingredient quality
  • No Parabens allowed for preservation

The Environment

The positive environmental impact

  • In the UK, organic farms have 44% more birds and more than five times as many wild plants

The Future

  •  The future looks better for all of us, when sustainable crop production methods, that work with nature, are employed

Is YES Vegetarian Approved?

The full YES product range are vegetarian approved.

The Vegetarian Society’s trusted “Seedling” symbol awarded to YES WB and OB products is a further endorsement of our ethics and ingredients philosophy.

As an educational charity promoting understanding and respect for vegetarian lifestyles, they have approved our products as free from animal derived and GMO ingredients.

Are there preservatives in Yes products?

YES VM vaginal moisturiser contains the preservative Phenoxyethanol.

YES WB water based uses two different preservative systems, which are Sodium benzoate and Phenoxyethanol.

YES OB plant-oil based contains no preservatives, only Vitamin E which acts as an antioxidant and extends the shelf-life.

We have to buy the synthetically produced versions as we don’t use animal body parts and we cannot find commercially available plant extracted sources. They are approved by the FDA and UK/EU bodies for food and/or cosmetic applications, as well as by our Organic certifier: The Soil Association.

To date we have found no naturally occurring preservative package that is safe, non irritant and effective. Used correctly (not above 1%) both these preservatives do a brilliant job without being skin irritants or having any other concerns associated with them. In the absence of chemicals know to be penetration enhancers, like Propylene glycol, they are not pulled thought the skin into the blood stream. YES products contain NO penetration enhancers.

We are often asked why we use preservatives in our natural products, when we have striven to make our products as natural as possible. Unfortunately preservatives of some kind will always be needed in water-based products. Water is the basis of all life, and that includes bacteria, fungi and moulds. Products without preservatives will have a very short shelf life, even if refrigerated (think of milk or orange juice). Products that are not properly preserved, even if made in a very clean environment, will become a health risk when exposed to the microbes present in life. So we preserve our products to give them shelf life and to ensure they are hygienic – to protect you. And as registered Medical Devices our products also have to meet strict preservation standards.

If you follow the link and read our ingredients page then you will know that we are on a permanent hunt for a more truly natural and effective preservative. This page says:

Preservation and product cleanliness are critical. We tested all commercially available natural and “natural” preservation systems and found that none were secure, reliable and safe enough to meet our criteria. For instance Grapefruit seed extract is a known eye irritant at low concentrations. We finally chose a combination of natural and synthetic preservatives for YES WB to deliver the performance required.

All YES products are certified organic by the Soil Association in the UK, this supports our ingredients policy, in that we can only use certain approved (gentle) preservatives (e.g. no parabens).

YES products are the only range of certified organic lubricants available – anywhere. This makes YES the purest and the most natural range of personal lubricants and vaginal moisturisers. One of the great things about YES is that performance is NOT sacrificed in the pursuit of purity – check out our Yestimonial.

Why does my YES OB (plant-oil based) have a granular texture?

If you experience an undesired granular texture we can reassure you that what you are experiencing is perfectly normal and it is a function of us using natural raw materials, and the Shea butter may crystallise out when it is warmed above body temperature and cooled slowly.

YES OB is designed to melt at body temperature so it is a thick paste in the tube and a liquid lubricant when needed but if cooled slowly the Shea butter can form grainy crystals that do look like sand. If you rub/warm the grainy crystals you will see that they melt in your hand. Our advice is to warm it completely so it’s all a liquid, in a mug of hot, not boiling water, shake the tube to mix it up and pop it in the fridge to cool quickly.

This is a function of using exclusively natural ingredients – they do not always behave in the way we want them to; the product is perfectly safe to use.