(MayoClinic.com) Cold remedies are almost as common as the common cold, and many are nearly as ancient. The use of chicken soup as a congestion cure dates back centuries. But is longevity any guarantee that a cold remedy works? Do effective cold remedies even exist? Here's a look at some common cold remedies and what's known about them.

If you catch a cold, you can expect to be sick for one to two weeks. But that doesn't mean you have to be miserable. These remedies may help:

• Water and other fluids. Water, juice, clear broth or warm lemon water with honey helps loosen congestion and prevents dehydration. Avoid alcohol, coffee and caffeinated sodas, which can make dehydration worse.
• Salt water. A saltwater gargle — 1/4 to 1/2 teaspoon salt dissolved in an 8-ounce glass of warm water — can temporarily relieve a sore or scratchy throat.

• Saline nasal drops and sprays. Over-the-counter saline nasal drops and sprays combat stuffiness and congestion. In infants, experts recommend instilling several saline drops into one nostril, then gently suctioning that nostril with a bulb syringe. To do this, squeeze the bulb, gently place the syringe tip in the nostril about 1/4 to 1/2 inch (about 6 to 12 millimeters) and slowly release the bulb. Saline nasal sprays may be used in older children.

  Unlike nasal decongestants, saline drops and sprays don't lead to a rebound effect — a worsening of symptoms when the medication is discontinued — and most are safe and nonirritating, even for children.

• Chicken soup. Chicken soup might help relieve cold and flu symptoms in two ways. First, it acts as an anti-inflammatory by inhibiting the movement of neutrophils — immune system cells that participate in the body's inflammatory response. Second, it temporarily speeds up the movement of mucus, possibly helping relieve congestion and limiting the amount of time viruses are in contact with the nose lining.

• Over-the-counter cold and cough medications in older children and adults. Nonprescription decongestants and pain relievers offer some symptom relief, but they won't prevent a cold or shorten its duration, and most have some side effects. If used for more than a few days, they can actually make symptoms worse.

  Experts agree that these medications are dangerous in children younger than age 2. The Food and Drug Administration (FDA) is evaluating the safety of over-the-counter cold and cough medications in older children.

  Keep in mind that acetaminophen (Tylenol, others) can cause serious liver damage or liver failure if taken in doses higher than recommended. It's common for people to take Tylenol in addition to flu medications that may also contain acetaminophen, which can lead to acetaminophen overdoses. Read the labels of any cold medication carefully to make sure you're not overdosing.

  If a cough lasts after your other cold symptoms have resolved, see your doctor. In the meantime, try soothing your throat with warm lemon water and honey and humidifying the air in your house. Don't give honey to infants.

• Antihistamines. First-generation (sedating) antihistamines may provide minor relief of several cold symptoms, including cough, sneezing, watery eyes and nasal discharge. However, results are conflicting and the benefits may not outweigh the side effects.

• Humidity. Cold viruses thrive in dry conditions — another reason why colds are more common in winter. Dry air also dries the mucous membranes, causing a stuffy nose and scratchy throat. A humidifier can add moisture to your home, but it can also add mold, fungi and bacteria if not cleaned properly. Change the water in your humidifier daily, and clean the unit according to the manufacturer's instructions.

  If your infant has a cold, sitting in a steamy bathroom for a few minutes before bedtime may also help.

The list of ineffective cold remedies is long. A few of the more common ones that don't work include:

• Antibiotics. These attack bacteria, but they're no help against cold viruses. Avoid asking your doctor for antibiotics for a cold or using old antibiotics you have on hand. You won't get well any faster, and inappropriate use of antibiotics contributes to the serious and growing problem of antibiotic-resistant bacteria.
• Over-the-counter cold and cough medications in young children. OTC cold and cough medications may cause serious and even life-threatening side effects in children. The FDA warns against their use in children younger than age 2. The Consumer Healthcare Products Association has voluntarily modified consumer product labels on OTC cough and cold medicines to state "do not use" in children under 4 years of age, and many companies have stopped manufacturing these products for young children. The FDA is evaluating the safety of these medications in older children.

• Zinc. The cold-fighting reputation of zinc has had its ups and downs. That's because many zinc studies — both those that find the mineral beneficial and those that do not — are flawed. The highest quality randomized trials generally show no benefit. In studies with positive results, zinc seemed most effective taken within 24 hours of the onset of symptoms. Taking zinc with food may reduce side effects, including a bad taste and nausea.

  Intranasal zinc may result in permanent damage to the sense of smell. The FDA issued a warning against using three zinc-containing nasal cold remedies because they had been associated with a long-lasting or permanent loss of smell (anosmia).

In spite of ongoing studies, the scientific jury is still out on some popular cold remedies, such as vitamin C and echinacea. Here's an update on some common alternative remedies:

• Vitamin C. It appears that for the most part taking vitamin C won't help the average person prevent colds. However, taking vitamin C before the onset of cold symptoms may shorten the duration of symptoms. Vitamin C may provide benefit for people at high risk of colds due to frequent exposure — for example, children who attend group child care during the winter.
• Echinacea. Studies on the effectiveness of echinacea at preventing or shortening colds are mixed. Some studies show no benefit. Others show a significant reduction in the severity and duration of cold symptoms when taken in the early stages of a cold. One reason study results have been inconclusive may be that the type of echinacea plant and preparation used from one study to the next have varied considerably. Research on the role of echinacea in treating the common cold is ongoing. In the meantime, if your immune system is healthy and you aren't taking prescription medications, using echinacea supplements is unlikely to cause harm.

Although usually minor, colds can make you feel miserable. It's tempting to try the latest remedy, but the best thing you can do is take care of yourself. Rest, drink fluids and keep the air around you moist. Remember to wash your hands frequently.

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