Potassium or sodium bromide are the salts most used. They have no action on the skin, and are mildly irritant to mucous membranes from which they are absorbed. They depress the heart, quiet the brain, causing sleep, and depress the spinal cord, inhibiting its motor activity. They cause death by paralyzing the nerve centers.

They are excreted slowly, principally in the urine, par-tially by the skin.