Chewing ice can be a symptom of iron deficiency anemia but can also be related to pica, a condition in which people crave and chew nonfood items like ice, soil or paper, notes Mayo Clinic. Doctors don't know what causes some people with anemia to crave ice, as of 2015.
One study has shown that people with iron deficiency anemia may feel more alert after chewing ice, states Mayo Clinic. People with emotional problems related to stress, obsessive-compulsive disorder or developmental disorders may also suffer from pica and crave items such as ice. Doctors can determine through testing if patients have medical conditions such as anemia, and if tests are negative, they may refer people who crave and chew ice, known as pagophagia, to therapy.