Essential oils are some of the most amazing products of our natural world. The oils of aromatic plants have been used for centuries for both their smell and their medicinal applications. But just because something is natural doesn't mean it's good for you. Essential oils are powerful chemical compounds. They may smell wonderful...but they need to be used (both by you, the soap and candle maker, and by the people who will be using your soaps and candles,) carefully and conscientiously. ALL essential oils must be used with care. Here are several lists of essential oils that need to be used with extra care.
There are some essential oils that will cause skin irritation in people with very sensitive skin. They affect some folks, but not others - and not always right away. People can have no reaction to an essential oil for a while...and then suddenly have a reaction.
Just because something is natural doesn't mean it's good for you. And just because something is good...doesn't mean that more is better. There are some essential oils that can irritate the skin if used in too high a concentration.
Though they may smell great, there are some essential oils that just need to be left alone...or at the very least, only used only by someone with significant essential oil experience.
Just because something is natural doesn't mean it's good for you. And just because it's good for you, doesn't mean that it's good for small children or babies...or while you are pregnant. Some essential oils have hormone-like effects, others stimulate the uterine muscles, others are just plain toxic. My rule of thumb, especially when there is a growing baby to consider, is an emphatic "better safe than sorry."
There are a number of essential oils that have chemical components that, while completely natural, need to be used with caution. Some are just "photo" toxic - that is, they become toxic when exposed to the sunlight. Others are just plain toxic, and should be avoided.