I feel it on the spot that was sensitive to cold, and that was the reason I looked for something new. The paste is of room temperature, so that feeling must be not a fluke. No idea if it actually works, F+Ca used to be enough.

I use toothpaste with Novamin and I also feel burning / heat. It begins immediately and lasts for about 2 minutes.

I don't feel anything when using it, but it does do a much better job with hot / cold sensitivity than anything else I have tried on the market. I find it more effective than Biomin or Nano-Hydroxyapatite.