It is important to understand the possible precautions and contraindications of the essential oil being used - but first you need to understand the difference between these two terms.
1 - Precaution: means that you must be CAUTIOUS when using an essential oil because it MAY have an adverse effect
Peppermint MAY disrupt sleep patterns so it is best avoided at night
Black Pepper MAY cause skin irritation if used topically
Bay Laurel MAY cause skin irritation if used for a period longer than 3 weeks
2 - Contraindication: means you must AVOID using an essential oil because it WILL have adverse side effects.
Bergamot - DO NOT go into directly sunlight after applying topically, will cause photo-sensitivity due to bergaptene content.
White Camphor - DO NOT use with epileptics or asthmatics, causes shortness of breath.