Histamines, antihistamines, the placebo effect and Victorian mosquito plague

Ever wondered what histamines are, and why some people are anti-histamine? Stu finds out why histamines are actually important and why stopping them permanently might be a bad idea. Chris looks at a new review questioning the very existence of the placebo effect. And Claire discovers that South Eastern Australia is undergoing a mosquito plague of biblical proportions, and wonders if it's a bad thing or not.