Two main complications that arise with dengue fever are severe dehydration and fever-induced seizures. Dengue fever can cause high body temperatures and vomiting, which in turn causes a loss of fluids. It is very important to replace those fluids otherwise you may need to be admitted to a hospital to receive fluids through a needle in your arm or hand.
Due to the very elevated body temperatures caused by dengue fever, children have been found to suffer febrile convulsions. Febrile convulsions are seizures that are brought on by the fever and in industralized nations occur in less than 5% of children affected with high fever.