Essential oils are generally safe to use in adults. However, essential oils that have passed their shelf life or that contain synthetic compounds may be unsafe due to their lack of purity. Some essential oils have a higher chance of causing skin irritation than others, and many are not recommended for children due to the risk of allergic reactions and toxicity. Essential oils are generally safe to use in adults. However, essential oils that have passed their shelf life or that contain synthetic compounds may be unsafe due to their lack of purity. Some essential oils have a higher chance of causing skin irritation than others, and many are not recommended for children due to the risk of allergic reactions and toxicity.