Why did the other patient in the room regret his deal about the cold and the hand in that one Twilight Zone?

In early 1964, Rod Serling introduced us to the Twilight Zone episode"The Self-Improvement of Salvadore Ross" which showed a man who could switch physical and emotional characteristics with the people around them. After breaking his hand, he made a deal with a fellow patient at the hospital who was sick saying that he would switch the busted hand for the other patient's cold, and the other patient agreed. Later, he was upset he did it. Why did the other patient regret his deal?