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.
It's important to remember that not all drugs will produce the same degree of pupil dilation. For example, MDMA will have a much more profound effect on pupil dilation than, say, an antidepressant. And interestingly, other drugs, like opiates, cause the opposite effect â pupil contraction, or what's known as miosis.