An infusion is a water-based preparation in which a cup of hot water is poured over a teaspoon of dried herbs, is covered for 10-15 minutes, and then the herbs are strained. I should mention that the difference between a beverage tea, such as a cup of chamomile before bed, and a medicinal tea is that to be considered medicinal the tea MUST be covered so that the medicinal qualities of the volatile oils do not escape in the steam. Because they are also infused for a longer period of time medicinal teas are not necessarily tasty, and honey, sugar or licorice can be added to make them more palatable. The advantage of this method is that it is fast, easy, relatively safe, and very accessible for most people. This is a good method for self-care and the functions of many dried herbs can be found in books and online. The disadvantage is that they are not incredibly strong medicine and there are herbs in which the medicinal components of the plants are not released in hot water alone and must either be boiled for some time or extracted with alcohol.
Like infusions, decoctions are a water based preparation. The difference is that the herb material is cooked in water for an extended period of time over a flame, such as on a stove. The Western herbal technique is to put one teaspoon of dried or three teaspoons of fresh herb material for each cup of water into a pot. The water is then brought to a boil and left to simmer for ten to fifteen minutes. Again, they should be covered especially if the herbs used contain volatile oils. The decoction is then strained and administered while still hot in a single dose.
Chinese herbal decoctions are a bit more complicated. A mixture of anywhere from 2 to 20 dried herbs are combined and put into a pot. If the herbs are especially hard, such as bark, twigs or roots, the plants are either cut into small pieces, or ground into a powder and placed in a muslin bag. The herbs are covered with about 4 cups of water and left to sit for a bit to soften them up. The water is then brought to a boil and simmered for 40-60 minutes or until 2 cups of water remain. The herbs are strained and the liquid is reserved. The herbs are then covered a second time with 4 cups of water and the process is repeated until 2 cups remain. The herbs are strained and the water is added to the first batch of liquid. The herbs are discarded. The 4 remaining cups of liquid are drunk over the next 2 days, one cup twice a day.
Some herbs are left out of the pot originally and added at the end of the decoction, such as bo he (mint). Some are cooked for much shorter periods of time with a lid (to protect those oils again!) and some are cooked longer to reduce any toxicity that might occur with that particular herb. Due to this, when making a Chinese decoction it is important to know a bit more about the qualities of specific herbs or to follow directions given by a trained herbalist. This means that decoctions have the disadvantage of not being particularly good for self-treatment, but they do have the advantage of being very strong and great for acute situations. They are also very messy, take time and effort, smell up a house, and generally taste terrible. For this reason, many Western clinics no longer prescribe them because compliance with taking herbal formulas is low.
I encourage anyone who has the opportunity, to use a Chinese medicinal decoction at least once to experience it. It is an ancient form of medicine, very effective, and a wonderful experience. A lot of healing is gained when one works closely with one’s own herbs. To look at them dried, sift through them, smell them, try to identify them (is that a dried insect???) and then to smell them cooking before taking them internally is all a part of the healing process. It may not be the most practical way to take herbs on a long term basis, but it will bring someone closer to the roots of Chinese Medicine.