Liquid nitrogen freezing is possibly the treatment that is performed the most by doctors and dermatologists to treat molluscum contagiosum. It is, in fact, effective in treating molluscum. Unfrotunately, though, it is effective against a few specific bumps only.
A doctor will apply liquid nitrogen directly onto a bump to freeze it and kill the virus inside. Each bump needs to be treated and frozen individually. Because of this, it is only effective if you have a few small bumps that have just recently appeared. Bigger bumps are more difficult and more painful to freeze, and if the bumps are widespread, it will be almost impossible to treat them all. Furthermore, the treatment is very localized because a bump has to be treated individually. Therefore, surrounding skin will still be infected and new molluscum bumps will start appearing around the treated bump a few days after the treatment.
Freezing of the skin is like a burn, so you will definitely feel a burning sensation when the liquid nitrogen is applied, but it will not be very painful unless the bump is big and a considerable a size of skin needs to be frozen. Children will be more sensitive to the pain.
My molluscum bumps were treated with liquid nitrogen. A month after molluscum appeared on my neck, I went to a doctor's. At that point, there were 3 small pearly bumps in a row. The doctor diagnosed them as molluscum and treated them with liquid nitrogen on the spot. 2 weeks later, I went back. The original bumps were still there, and I had 4 new ones around the same area. The doctor treated them again, a bit more severely this time. Within a week, half of those bumps looked like they were recovering, but I had new ones popping up all over the same area, so I did not bother going back again. In addition, there is some scarring. The areas that were treated with liquid nitrogen remained darker than the rest of the skin. Six months later, the skin coloration was still there.
Liquid nitrogen is an effective treatment if you have a few molluscum bumps that have just recently appeared. Once the bumps have grown a bit in size and are more spread out and well-established, liquid nitrogen will not longer be a viable treatment option.