Plan B is a progesterone only medication which delays ovulation. Since it is a naturally occuring hormone, it is unlikely that anyone could die from taking it, unless they attempted to overdose. Attempting to do so would be stupid and difficult, since when you buy it, you only get one dose.

There have been no known fatalities resulting from Plan B. The pills sometimes cause nausea, vomiting, headaches, dizziness, cramping, fatigue or breast tenderness. It can also cause delayed or irregular period for a while.

None of the symptoms are particularly serious. In the unlikely event that there was a fatality, the maker of the drug would be liable, as with any other drug on the market.