The Incredible Shrinking Man (1957)

While on a boating trip, Scott Carey is exposed to a radioactive cloud. Nothing seems amiss at first, but several months later Scott realizes that he's shrunk in height by several inches. He sees a doctor, who admits that he's baffled. As Scott continues to shrink, decreasing to three feet tall, he becomes bitter, and lashes out at his wife, Louise. He begins to fear a cure will never be found -- since even as he becomes a national sensation, he's still shrinking.

Source: TMDb