Largely because of their perceived safety, the use of essential oils and other botanically derived products has become increasingly popular. Recent evidence raises concern about the safety of these products, frequently found in cosmetics and sought as an alternative to standard medical treatments. Essential oils are challenging to standardize because of the variable growing conditions, genetics, and harvesting of botanicals. There exists a potential for adverse reactions, in particular allergic contact dermatitis. Furthermore, these products are often sold without prior Food and Drug Administration approval of efficacy and safety. This review focuses on the composition of essential oils, their common associated botanical allergens, and current regulation practices of botanical drug products in the United States and Europe.