Sometimes you may find a strand of hair in your soup and just decide to overlook it and swallow it together with the soup. A single hair strand is not really dangerous as it is very small and the highest possibility is that it will just pass through the digestive tract. However, the hair poses a danger when it forms a clump, which would eventually form a giant hairball in your stomach necessitating the need to see a doctor. So, what happens when you swallow hair?