Considering trying a fertility lubricant, but confused by the information about pH levels? Dust off your old high school chemistry book; let’s do a refresh on what pH is in the first place!


By fertility expert and OBGYN Dr. Kenosha Gleaton

Dust off your old high school chemistry book; let’s do a refresh on what pH is in the first place. pH is a scale, from zero to 14, used to specify the acidity or alkalinity of a water-based environment. A lower number is more acidic (think: orange juice, which has a pH of around 3.5). Substances with a high pH, like bleach, which has a pH of 13, are alkaline. In the middle, there is pure water, which has a pH of seven and is considered “neutral” because it has neither acidic nor basic qualities. A pH greater than seven is considered “basic.”

A healthy vagina is somewhat acidic

A healthy vagina is moist and somewhat acidic, with a pH between 3.8 and 4.5. But the pH of semen ranges from 5.2 to 8.2. Does it matter that they are different? Nope! The body is amazing. When sperm (which are slightly alkaline) enter the vagina, it raises the vagina’s pH, temporarily neutralizing vaginal acidity. This makes the vagina and cervix more hospitable to sperm, allowing sperm a better shot at meeting the egg.  

Why a basic vagina is bad

The acidic pH of the vagina is a good thing. The vaginal microbiome has “good” bacteria called Lactobacilli, which help protect women against sexually transmitted diseases and other infections.

A basic vagina, one with pH above seven, can be problematic. Lubricants, douching, and other products with a higher pH may increase risk of bacterial vaginosis (BV). Serious adverse health outcomes have been associated with BV, including increased risk of infertility, adverse pregnancy outcomes, preterm birth, and miscarriage

The World Health Organization agrees

The World Health Organization (WHO) published guidelines on what to look for in a lube:

“When procuring water-based lubricants, a pH of around 4.5 is recommended if the primary intended target population will use the product for vaginal intercourse. Lubricants with pH exceeding 7 are not recommended.”

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Our fertility friendly lubricant, The Lube, is water-based and pH-balanced. It uses a buffering action to adapt pH during intercourse to maintain a healthy vaginal pH (thereby reducing chances of infections) while being sperm friendly. It acquires the pH of the environment, meaning it matches the elevated pH of semen and cervical mucus. Its gentle buffering capacity also means it does not raise vaginal pH to unhealthy levels.

Osmolality is also important

Osmolality is a test that measures the concentration of all chemical particles found in a fluid. The osmolality of healthy vaginal fluid is around 370 mOsm/kg in women. The body is constantly trying to maintain equilibrium of osmolality, so if a lubricant has high osmolality, the body will react by releasing moisture in an attempt to reach homeostasis with the lubricant. Using lubricants with high osmolality may cause vaginal and anal epithelial damage and increase the risk of infection.

Because of this, the World Health Organization (WHO) suggests only using lubricants with an osmolality below 1,200 mOsm/kg. The Lube is made with this in mind and comes in under 400 mOsm/kg. 


  • A healthy vagina is moist and somewhat acidic (with a pH between 3.8 and 4.5).
  • High vaginal pH can put you at higher risk for infection.
  • The WHO recommends using water-based lubricants with a pH around 4.5.
  • The WHO recommends only using lubricants with an osmolality below 1,200 mOsm/kg.
  • The Lube follows these guidelines and is FDA cleared to be sperm friendly.


Featured Image by Min An