The reason for sperm damage from most products can be seen when data on product pH and osmolarity are compared as in the table below.

The optimum pH value for sperm migration and survival in the cervical mucus is between 7.1 and 8.5 (according to the World Health Organization Manual 4th edition, 2000). Sperm are very sensitive to low (acidic) pH and, to a lesser extent, elevated (alkaline) pH. Below pH levels of 6.9, sperm die at a rate that increases with lowering pH.

Sperm are also sensitive to both high and low osmolarities (ion concentration in solution). A physiologic osmolarity between 260-360 mOsm/kg (that of semen) is best for sperm function.

Adapted from: Rossato M, et al. Role of seminal osmolarity in the regulation of human sperm motility. International Journal of Andrology. 2002; 25: 230-235.

Usually ingredients like glycerin or propylene glycol (in most lubricants), are what result in these high osmolarities.  We have tested many products besides the ones shown here.  If any glycols or mineral oils are in the lubricant you are using, you can pretty much assume the formula will be damaging to sperm. 

Water also kills sperm on contact because it has no salt solution.  Some people will tell you to use a little warm water--- don’t’! 

Likewise, saliva has digestive enzymes in it that stop sperm from swimming on contact—not so good if you want them to reach the egg!  

Even mineral oil which some doctors recommend, has been shown to limit the ability of sperm to penetrate eggs in laboratory studies (likely due to the high osmolarity as shown in the Table). 

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