Hi there,
Yes, it is apparently harmful to the sperm - with the exception of Preseed & Conceive Plus which are helpful to TTC by mimicing natural vaginal secretions.
This is what I found online:
Yes. Research has found that vaginal lubricants are toxic to sperm and interfere with the role of the cervical mucus.
Normally, the vagina's own acidic secretions kill sperm, but the alkalinity of the cervical mucus produced just before ovulation protects the sperm. Artificial lubricants prevent the sperm from reaching the cervical mucus quickly, so they die in the acidic environment of the vagina before getting inside the uterus. (There is one brand of lubricant on the market, called Pre-Seed, that is said to be designed not to damage sperm.)
Any artificial lubricant, whether store-bought or found at home (such as egg whites or mineral oil), presents a potential problem. The best lubricant to use when conception is your goal is foreplay. Take your time working up to intercourse.
If you still have minimal mucus despite all attempts at foreplay, try using warm water as a lubricant. Water isn't toxic to sperm and won't interfere with the sperm's ability to reach the cervix.
Not sure that warm water would be any help as the information suggests, but I would recommend Conceive Plus or Preseed. I'm using Preseed and it's great for days when i don't have much CM.
Good luck TTC.
Best wishes xx