Are Supplements dangerous?
Absolutely not! There is an argument to say that anything can be harmful if taken to excess on a regular basis - even water - but there has never been a recorded death from consuming vitamin supplements. Common sense is key.
Despite numerous scare stories, it's virtually impossible to overdose on vitamin pills providing you follow the label directions. You can even take several supplements together, as long as the total level of any particular nutrient doesn't reach an unsafe level.
Asking what's an unsafe level is a bit like asking how long is a piece of string, as it all depends on individual make up. Just as some of us have brown eyes and others have blue, some of us could happily tolerate levels that others might not. Don't forget also, that many vitamins are water soluble - they are not stored in the body - the body takes what it needs and the rest wash right through.