Dosage: 4 g of fresh garlic (about one medium-sized clove) or 8 mg of volatile oil daily is recommended; if you prefer capsules, make sure that they are enteric-coated. Take one capsule twice a day during a cold.

Elderberry
Sambucus nigra
Teas of elderberry fruits or flowers have been used for centuries in folk medicine to treat the symptoms of colds and flu; in Europe, elderberry flowers are commonly used as a diuretic. Recent research from Israel indicates that elderberry fruit extract may deactivate flu viruses by preventing them from replicating (flu viruses must reproduce or they cannot infect the body). Although this finding is exciting, it has yet to be confirmed.

Dosage: Take 40 drops of the liquid fruit extract daily or 2 to 4 g of the dried flowers in an infusion once a day during the first signs of a cold. Elderberry is available in powders, capsules, and other forms. So far, no side effects or contraindications have been reported.

Full-blown
If a cold has persisted for three or four days, you may feel as though it has settled in for good. Your throat, sinuses, and lungs may be severely inflamed; if your cold has settled deeply in your lungs, the phlegm that you cough up is thick, and your chest feels tight and sore. Now is a good time to try goldenseal, osha, or pleurisy root.

Goldenseal
Hydrastis canadensis
The root of goldenseal is believed to help chronic inflammation of the mucous membranes, such as those lining the throat, sinuses, and lungs. In secreting mucus, which traps and immobilizes bacteria and viruses, healthy mucous membranes serve as the body's first-line defense against intruders. When they become inflamed, however, they lose their ability to secrete mucus, and microbes are able to enter the circulatory system. Two alkaloids in goldenseal, berberine and hydrastine, are believed to contribute to the root's ability to reduce inflammation of the mucous membranes, enabling the tissues to resume their protective role. Further research is needed to establish this.

Goldenseal is one of North America's most popular herbs; however, overharvesting of roots from the wild and other factors have led to recent shortages and high prices. Increased cultivation of goldenseal is expected to alleviate the scarcity within five to ten years.

Dosage: 0.5 to 1 g of the powdered root daily or 20 to 30 drops of the liquid extract or one capsule every two to three hours. Take goldenseal only until the inflammation is gone, then stop: long-term use can kill beneficial intestinal organisms. Do not take goldenseal if you are pregnant (it can cause uterine contractions) or if you have high blood pressure.

Osha
Ligusticum porteri
Osha, or Porter's lovage, is an herb of the carrot family (Umbelliferae) native to the Southwest. It has been used for centuries by Native Americans to treat sore throats, lung congestion, and other respiratory disorders.

During colds and flu, the body loses moisture, and mucus becomes thick and difficult to expel. Thick mucus provides a place for germs to multiply. Osha can help by keeping the mucus in the lungs wet and fluid, stimulating the cilia on cells of the mucous membranes in the lungs to move debris-laden mucus up and out into the throat, and decreasing inflammation of the respiratory tract.

Dosage: The root of osha is the part used medicinally; take during infection only. Take 10 to 30 drops of the liquid extract or one capsule every three to four hours, up to five times a day. Do not use during pregnancy.