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.
Eyes dilate for many reasons. They mainly dilate to control the amount of light that enters the eye. Pupils become smaller when the light is bright, and larger in the dark. Eye doctors dilate eyes to check for signs of disease. Eyes can also dilate as a result of an illness, or another condition or emotion. The circular and radial muscle of the iris control eye dilation. The radial muscle responds to dim light and will cause your pupil to become larger. The circular muscle reacts to bright light and causes the pupil to grow smaller.