Complementary therapies for the common cold

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:

How do I use it?

The usual dosage is 13 to 23 mg of zinc as zinc gluconate or zinc acetate every 2 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?

Echinacea is thought to work by temporarily stimulating the immune system, although this 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.
  • Among a group of 80 people with early cold symptoms, those given E. purpurea recovered in 6 days; those given placebo recovered in 9 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.
• 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 7 to 14 days. The three main types of echinacea can be used interchangeably. Depending on the form, dosages are:

• Echinacea powdered extract – 300 milligrams (mg), 3 times a day
• Alcohol tincture (1:5) – 3 to 4 milliliters (ml), 3 times daily
• Echinacea juice – 2 to 3 ml, 3 times daily
• Whole dried root – 1 to 2 grams (g), 3 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 2 of treatment, and even more by day 4, 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 6 g/day of andrographis decreased symptoms of fever and throat pain as well as acetaminophen. However, 3 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 3 times a day. Doses as high as 1,000 to 2,000 mg 3 times daily have been used in some studies. Andrographis is usually standardized to its content of andrographolide, typically 4 to 6%.

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 over-hyped. 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: 30mg (considered the placebo), 1000mg, 3000mg, or 3000mg 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: