Herbal teas have been in use for centuries. They have been consumed for their medical properties but also as nutritional supplements and simply for their taste and comfort.
Most of the teas you will find at your supermarket or health food store will have some information regarding what benefit the teas' ingredients are thought to deliver to the body. Of course, many of these claims are part of the historical record, not necessarily approved by the FDA (no company is going to spend its money researching and proving or disproving the health claims of a product they do not have a monopoly on). That being said, take any exaggerated claims with a grain of salt.
When you are undergoing a detoxification program, your body is ridding itself of built up toxins you've accumulated through diet or your environment. While releasing these toxins from where they are stored in the body, you may experience some discomfort as they are working their way through your system. Chamomile tea is an excellent choice for relaxation. It has a mild sedative effect and eases digestion. It is a wonderful choice at night before retiring.
Chamomile is one of the prime ingredients in the popular 'sleepy time' tea from Celestial Seasonings. It is an excellent choice at night as well.
Green tea contains powerful antioxidants, hundreds of times more powerful than such workhorse antioxidants as vitamins E and C. This kind of antioxidant power is great for a detox program. Any errant oxidants let loose from their resting places can be snapped up by the forces inside green tea. Drink as much of this tea during your detox as you wish. The only caveat is that it does contain caffeine. It's best to stop drinking green tea in the afternoon as to not interfere with a good night's sleep.
Teas containing milk thistle and / or dandelion are very beneficial for the health of your liver. This is vitally important as the liver is the prime detoxifying organ in the body. During a detox program it will be operating at a peak rate and any tonic it receives will help it operate more efficiently.
Your next most detoxifying organs are the kidneys. Nettle tea comes to the rescue here. Nettles have a diuretic property which helps the kidneys rid the body of toxins quickly.
One main reason herbal teas are used during a detox program is to improve the speed at which your detoxifying system operates. This is important because these organisms, the liver and the kidneys (and to a lesser extent, the lungs and the skin) are dealing with an increased level of toxicity. Granted, those toxins have been in your body for a while but they have not been processed properly and removed. The faster the toxic substance exits the body, especially during this period of heightened activity, the better it is for your health all around.