Many illnesses are effects of dehydration. These include migraine and dehydration & obesity and dehydration. Illnesses beginning with letters K to O are outlined below.
Note that virtually any condition could be a symptom of dehydration because dehydration causes systemic problems.
Effects of dehydration can include cardiovascular, respiratory & immune system problems and cancers.
Sometimes symptoms of dehydration are indirect causes of another problem. For example, dehydration causes general immune suppression and that, in turn, leads to osteoporosis & osteoarthritis.
(Some conditions have links to further explanations. Other conditions will have further elaborations in the future.