Cold Remedies

Claims, Benefits: Prevent or treat the common cold.

Bottom Line: No convincing evidence that they work.

Full Article, Wellness Letter, February 2003:

Cold Remedies: A to Z

There’s hardly a plant that hasn’t been used at some time in hope of combating the common cold: gingerroot, garlic, andrographis, hyssop, wild indigo, myrrh, lemon balm, peppermint—everything in the dictionary, including those listed below. Some are said to prevent colds, some to ease such symptoms as nasal stuffiness, sore throat, or aches and pains. Here’s a run-down on some popular remedies (not all of them herbs) and their medical standing.

Astragalus: This Chinese herb, a kind of pea, is touted as an immune-system strengthener. In lab studies it shows some anti-oxidant properties and other promising activity. But there’s not enough evidence so far to evaluate its effectiveness or safety.

Echinacea: There are nine species of this daisy in North America, and three species are approved for use in Germany and elsewhere in Europe to treat the common cold. In Germany alone, more than a million prescriptions for echinacea are written each year. Some studies have shown that this herb can reduce cold symptoms. But there is large variation among the products on the market here; what species they come from, what part of the plant, and other factors can make a difference. Most reviews of studies on echinacea don’t find convincing evidence that it prevents colds or improves symptoms. There is probably no harm in trying it for a few days, unless you have a history of asthma or allergies triggered by pollen. People with auto-immune diseases, immuno-compromised people, and those on chemo-therapy should avoid it.

Elderberry: Teas made from the fruit or flowers of this plant have been used medicinally for centuries, and some people claim that they reduce flu symptoms. Taken as a hot drink with peppermint it may induce sweating. But the leaves and stems of the elder plant are poisonous, and so are the bark, roots, and unripe berries. Since there’s no way to know what you are getting in any store-bought preparation, we advise passing it up.

Goldenseal: Beloved of the Cherokee, this American plant is considered among the most powerful by herbalists, who claim it has antibiotic effects. It is believed to reduce inflammation and soothe mucous membranes. But no good research in humans backs up these claims. If you have heart disease or high blood pressure, goldenseal is not for you; it may interfere with anti-clotting and anti-hypertensive medications. Chronic use can reduce vitamin B absorption and cause digestive disorders. The risks outweigh any potential benefits.

Vitamin C: There is still no good evidence that large (or small) doses of vitamin C can do anything to prevent a cold, or lessen its symptoms in any meaningful way. A few studies have found that large doses can slightly reduce the duration of a cold—possibly by half a day—but that’s slicing it pretty fine. Most studies don’t even find this small benefit. Very large doses of vitamin C can cause diarrhea.

Zinc: This is an important nutrient for maintaining immunity. In lab tests zinc has been shown to interfere with the replication of cold viruses. But the evidence that zinc behaves this way in the human body is inconclusive. You’ll find zinc in many forms—zinc gluconate or zinc acetate in pills, sprays, and nasal gels. Too much zinc can actually impair immunity, as well as lower HDL ("good") cholesterol, cause nausea, and lead to a copper deficiency. Zinc can interfere with tetracycline and some other antibiotics. Zinc lozenges vary in strength, and there’s no consistent evidence they work; but the nasal sprays or gels might possibly reduce symptoms if you use them at the first sign of a cold.

Words to the wise

Just because herbs and minerals are "natural," that doesn’t mean they are safe; and just because they have been used for centuries, that doesn’t mean they work. If you have a cold, you’ll be better off with chicken soup, plenty of fluids, an over-the-counter pain reliever for aches and pains, and maybe a day or two in bed. Skip the herbs. And don’t take antibiotics for a cold or flu—they can do nothing against viruses. As far as the flu is concerned, the very best plan is not to get it at all—get a flu shot instead.

UC Berkeley Wellness Letter, February 2003