Potential side effects of magnesium oil include gastrointestinal discomfort, including watery or loose stools, according to The Huffington Post. The side effects, which are caused by over consumption of the supplement, occur with both oral consumption and topical use.
Magnesium oil is a mixture of magnesium chloride with water used to treat magnesium deficiency and regulate bowel movements, advises The Huffington Post. It is also effective for reducing inflammation, easing muscle pain caused by injury or arthritis, alleviating anxiety and improving sleep quality. The supplement has humectant properties that help to keep the skin moisturized. It is more readily absorbed through the skin than through oral consumption.