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When a cold strikes, many people immediately think of antibiotics to cure what ails them. However, antibiotics aren't effective against colds because colds are caused by viruses, and antibiotics are designed to fight bacteria, not viruses.

What about natural therapies? The evidence may still be inconclusive, but some of these natural therapies may help minimize the misery of a cold.

Consider these examples:


How Does It Work?

Zinc—in the form of zinc gluconate or zinc acetate—can be given as a nasal spray or as a lozenge to treat a cold. These forms of zinc release ions that directly inhibit viruses in the nose and throat.

What Is the Scientific Evidence?

The findings from scientific studies of zinc have been mixed; however, the overall results appear to be favorable. For example:

Zinc Nasal Spray

  • In a double-blind, placebo-controlled study, people given zinc nasal spray (zinc gluconate) had cold symptoms for an average of 2.3 days, while those who took a placebo were sick for an average of nine days.
  • Another study, which used a different form that had a lesser amount of zinc, did not find any benefit from the use of zinc.

Zinc Lozenges

  • In a double-blind trial, people took either zinc lozenges (13.3 mg of zinc gluconate) or placebo lozenges several times daily until their cold symptoms subsided. Those taking zinc saw their symptoms disappear one to three days sooner as compared with the placebo group.

How Do I Use It?

The usual dosage is 13 to 23 mg of zinc as zinc gluconate or zinc acetate every two hours. Begin taking zinc at the first sign of a cold and continue until symptoms subside; never take these forms of zinc for longer than two weeks.

Also, check the ingredient list and don't buy a lozenge that has citric acid or tartaric acid. These are often added to improve flavor, but they can block zinc's antiviral action.


How Does It Work?

While echinacea has been promoted as a substance which temporarily stimulates the immune system, this action has not been proven. There is no evidence that echinacea strengthens or "nourishes" the immune system when taken over the long term.

There are three main species of echinacea:

  • Echinacea purpurea
  • Echinacea angustifolia
  • Echinacea pallida

E. purpurea is the most widely used, but the other two are also available. It isn't clear if any one type is better than the others.

What Is the Scientific Evidence?

Echinacea has been the subject of much study. Among some of the cold and flu-related research is the following:

  • Several double-blind, placebo-controlled studies enrolling a total of more than 1,000 individuals have found that echinacea can make colds shorter and less severe. Other studies have found no effect from echinacea.
    • Among a group of 80 people with early cold symptoms, those given E. purpurea recovered in six days; those given placebo recovered in nine days.
    • A study of 246 people given E. purpurea found that those taking the herb had significantly less severe symptoms, such as runny nose, sore throat, sneezing, and fatigue than those taking placebo.
    • A double-blind, placebo-controlled trial, involving 524 healthy children between the ages of 2-11, found that echinacea did not affect the duration or severity of cold symptoms compared to the effects of a placebo.
  • Several studies have tried to determine if taking echinacea regularly will prevent colds. However, no studies have shown this to be true.

How Do I Use It?

Echinacea is usually taken at the first sign of a cold and continued for seven to fourteen days. The three main types of echinacea can be used interchangeably. Depending on the form, dosages are:

  • Echinacea powdered extract: 300 mg, three times a day
  • Alcohol tincture (1:5): 3-4 ml, three times daily
  • Echinacea juice: 2-3 ml, three times daily
  • Whole dried root: 1-2 g, three times daily


How Does It Work?

Andrographis is a shrub found throughout India and other Asian countries. It is sometimes called "Indian echinacea" because it is believed to provide many of the same benefits. It is unclear how andrographis helps to prevent and treat colds, but some evidence suggests that it might stimulate immunity.

What Is the Scientific Evidence?

According to a few well-designed studies, andrographis can reduce the symptoms of colds and possibly prevent colds as well. Here's a sampling of the evidence:

  • Three double-blind, placebo-controlled studies enrolling a total of about 250 people have found that andrographis significantly reduces the duration and severity of cold symptoms.
    • In a 4-day double-blind, placebo-controlled trial of 158 adults with colds, people were given either 1,200 mg daily of an andrographis extract (standardized to contain 5% andrographolide) or placebo. By day two of treatment, and even more by day four, people given the andrographis extract had significant improvements in symptoms as compared with those given the placebo. The greatest relief was seen with earache, sleeplessness, nasal drainage, and sore throat, but other cold symptoms improved as well.
    • Another double-blind study, which involved 152 adults, compared andrographis with acetaminophen for the treatment of sore throat and fever. A dose of six g/day of andrographis decreased symptoms of fever and throat pain as well as acetaminophen. However, three g/day of andrographis did not have any effect. There were no significant side effects in either group.
  • According to one double-blind, placebo-controlled study, andrographis may increase resistance to colds. Over the course of three months, volunteers took either a dried extract of andrographis (two 100-mg tablets standardized to 5.6% andrographolide) or a placebo daily. By the end of the study, twice as many people in the placebo group as in the treatment group had colds.

How Do I Use It?

A typical dosage of andrographis is 400 mg three times a day, although as noted above this dosage was ineffective in at least one study. Doses as high as 2,000 mg three times daily have been used in some studies. Andrographis is usually standardized to its content of andrographolide, typically 4% to 6%.

Vitamin C

How Does It Work?

Vitamin C is a nutrient of great controversy. While some experts believe megadoses of this vitamin can keep you healthy, others feel it is overhyped. The truth is somewhere in the middle.

Many studies have found that vitamin C supplements—at a dose of 1,000 mg daily or more—can modestly reduce symptoms of colds and help you get over a cold faster. This evidence regards daily use of vitamin C throughout the cold season.

Many people use vitamin C for colds in a different way: they only begin taking it when cold symptoms start. Relatively few studies have evaluated this approach.

What Is the Scientific Evidence?

A large double-blind, placebo-controlled trial was recently conducted to determine whether vitamin C helps when taken only at the onset of a cold and for the following two days. The volunteers were divided into four groups depending on the amount of vitamin C they took per day: 30 mg (considered the placebo), 1000 mg, 3000 mg, or 3000 mg with additives.

The results showed no difference in the duration or severity of cold symptoms among the four groups. And the researchers concluded that high dose vitamin C does not help to lessen the effects of the common cold.

There are two main possible explanations for these negative results:

  • Taking high dose vitamin C at the onset of a cold is not as effective as taking it continuously
  • Taking vitamin C at the onset of a cold could work, but that two days of treatment isn't long enough

How Do I Use It?

Vitamin C is available as a single dietary supplement. There is as much controversy about recommended levels as there is about the true health benefits of this vitamin. Many nutritional experts, though, recommend a total of 500 mg of vitamin C daily. This dose is almost undoubtedly safe. The Upper Limit (UL) established by the Food and Nutrition Board is:

AgeUpper Limit
1-3 years400 mg
4-8 years650 mg
9-13 years1,200 mg
14-18 years1,800 mg
19+ years2,000 mg

Safety of Complementary Therapies

Few of the substances discussed here are subject to regulation by the FDA. This lack of standardization means that actual dosages may differ from those given on the bottle or package. While widely used, few of these agents have been subjected to the kinds of official testing that the FDA requires for pharmaceuticals. If you take these substances be sure to inform your doctor. Some complementary therapies may influence the effectiveness or safety of medical prescriptions taken at the same time.