Colds and flu are both acute viral infections; mild cases may be difficult to distinguish. Colds typically produce nasal congestion, a scratchy throat, sneezing, and coughing, sometimes accompanied by a slight fever and blocked sinuses and Eustachian tubes. Flu tends to come on suddenly with a fever of 102ø to 104øF, severe headache, muscular aches and pains, exhaustion, and often a dry, hacking cough. Any of these symptoms can make for a poor night's sleep, leaving you fatigued the next day.

The search for ways to prevent and treat colds and flu has been going on throughout recorded history. Today many people consider them an inevitable fact of winter and are resigned to letting them run their course. While it's true that a cure for colds and flu does not exist, research during the past ten years into medicinal plants of Eastern and Western origin has shown that herbal medicines offer the potential to help the immune system stave off these bugs, as well as to speed healing if one of them has laid you low. Knowing which herbs to use and when in the cold cycle to take them are keys to using medicinal herbs effectively.

The following herbal supplements can help you weather the cold and flu season. Dosages of any medicine depend upon a person's size, age, and specific conditions, such as pregnancy, metabolic rate, and particular allergies, so seek a health professional's advice to determine needs specific to your body's condition. Suggested dosages given here are adult guidelines and should not be exceeded.

Defend yourself
Two of the best herbs for strengthening the immune system are astragalus and schisandra. Begin using them before colds and flu strike to take advantage of their immune-building potential.

Astragalus
Astragalus membranaceus
In scientific studies of astragalus in the United States and China, the root of this member of the pea family (Leguminosae) has been shown to increase nearly every phase of immune-system activity. One study showed that long-term use (thirty-five days) heightened immune-cell activity ranging from the speed with which immune cells develop to the speed with which they travel in the body. Another showed that astragalus increases the production and storage of interferon, a substance that alerts the body to invading viruses and bacteria and stimulates cells to begin their defense, and to increase interferon's effects in fighting illnesses such as the common cold.

Dosage: Take astragalus before colds and flu strike. The recommended dosage for adults is 9 to 15 g of the dried root taken daily for about one month in the form of a decoction. Astragalus root, capsules, teas, tinctures, and other product forms are available in health food stores. Astragalus has no reported side effects or contraindications.

Schisandra Schisandra chinensis
This herb is a vining shrub native to China. Its berries are used in traditional Chinese medicine to promote the production of body fluids and control coughing, to increase the body's resistance to a broad spectrum of adverse biological, chemical, and physical effects, and to help the body handle stress.