Ayurveda describe incompatibilities as the cause of disease in respect of food and other factors. One such common example is consuming fish along with milk. Other factors may not be so much aggravating, but on consuming them for a longer period it may happen. Unwholesome observance of different regimen are the basic cause of this disease besides code of right conduct.
According to modern system of medicine the cause is still not much clear. However, there are certain theories under various hypotheses which include- autocytotoxic, neurochemical and autoimmune theories.