Dehydration is one of the most worrisome complications of diarrhea in children. Mild diarrhea usually doesn't cause significant fluid loss, but moderate or severe diarrhea can. Severe dehydration is dangerous; it can cause seizures, brain damage, even death. Know the signs of dehydration.
Cough and cold medications and decongestants may cause the eyes to dilate. In general, any medication that is a stimulant may cause the eyes to dilate. While it's not particularly common, this could include ADHD medications such as Adderall or Ritalin. Of course, certain illegal drugs do this as well, such as cocaine.
Dilating drops work either by temporarily paralyzing the muscle that makes the pupil smaller (iris sphincter muscle) or by stimulating the iris dilator muscle. Patients with lighter eye color (blue, hazel) are more sensitive and dilate faster than patients with darker eye color (brown).