Massage can be a very effective treatment for a number of conditions. Massage helps with lymphatic drainage, which is important for detoxification, endocrine function and bolstering immunity. Massage also helps relieve muscular tension resulting from injuries or muscle spasms; such spasms can cause chronic pain and exacerbate existing injuries such as muscle sprains or tears. The use of essential oils during massage also offers an opportunity for healing, depending on which ones are used. Rosemary and peppermint ease muscular pain; lavender alleviates stress and insomnia; citrus oils can lift the mood and helo with minor depression.
Massages can make you feel relaxed. That is probably the only benefit you will receive. As far as complementary / alternative medicine is concerned, its often only the placebo effect that makes you feel better. Detox is just a myth. A healthy diet with adequate exercise will make you feel much better than complementary / alternative medicine.