Ingredients must also penetrate the skin and stay there long enough to have an effect.

Monk felt the cold close in on him, penetrating his skin.

A dagger that might not even penetrate the woman's skin?

A bullet traveling at only to can penetrate human skin,.

Beta radiation can penetrate human skin, but cannot go all the way through the body.

But for it to penetrate the skin, the maximum effective range is about ten inches.

The light reached far down into the soft X-ray region, to the point just above where it began to penetrate the skin.

I felt the warm trickle of blood as he penetrated the skin.

And I'm dubious about the ability of minerals to penetrate the skin.

Just in case a few did penetrate her skin.