Zinc for Colds: How Effective Is It in Preventing Symptoms?

Understanding Zinc and Its Role in Health

What Is Zinc?

Zinc is an essential mineral and micronutrient. The human body needs zinc in small amounts to function properly. Eating a healthy, balanced diet can ensure you get enough zinc. Taking zinc in the form of dietary supplements is not necessary for most people. 

Benefits of Zinc

The body needs zinc for cell division, growth, and development, in addition to immune system functioning, carbohydrate metabolism, insulin action, wound healing, and smell and taste.

Compared to placebo, studies have found supplemental zinc shortens the duration of cold symptoms. Additionally, participants report that zinc improves the severity of symptoms on day 3 but not the severity of the overall symptoms. However, experts do not recommend zinc as a cold treatment because the benefits do not outweight the potential side effects.  

Does Zinc Help With Cold and Flu?

Zinc is often used as a dietary supplement for the treatment of the common cold and flu. This is based on laboratory experiments showing that zinc ions can prevent rhinovirus (common cold viruses) from entering cells in the nasal epithelium and can interfere with viral replication. Zinc also plays a role in immune function and could potentially help the body fight respiratory tract infections. However, due to the mixed results for zinc supplements for common colds, zinc is not usually recommended to improve cold symptoms. Notably, study participants who take zinc report mouth irritation, taste problems, and stomach upset. You should talk to your healthcare providers before using zinc supplements for common colds or other reasons. 

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Zinc and the Common Cold

Can Zinc Prevent Colds?

Zinc cannot get rid of colds, and there is no guarantee that you will feel better with zinc while going through a common cold. However, placebo-controlled trials have found that taking zinc supplements daily can reduce the duration of symptoms associated with respiratory tract infections, such as the common cold, by 1-2 days. Fewer people fall sick with colds while taking zinc. However, safety information for long-term zinc supplementation is not available. Additionally, there is limited information on the type and amount of zinc that would work best. 

Can Zinc Treat Colds?

During clinical trials, zinc shortened the symptom duration of common colds by 1-2 days and also reduced symptom severity on day 3 (runny nose, stuffy nose, sore throat, postnasal drip, cough); however, zinc does not improve overall daily symptom severity. However, zinc supplements can cause unpleasant side effects, and they can be very serious in some cases.

When to Take Zinc for the Common Cold

Studies suggest that zinc works best if you take it as soon as possible after the onset of cold symptoms, ideally within the first 24 hours.

Scientific Evidence on Zinc for Cold Symptoms

Therapeutic Studies

Pooled results of randomized controlled trials have shown that people who took zinc had a shorter duration of illness with the common cold compared to those in the placebo group. Some researchers have found that zinc shortened the symptom duration of the common cold by 33% (2-3 days). Controlled trials have also found that zinc has a small to moderate effect on reducing the severity of common cold symptoms. Specifically, participants report that zinc improves the severity of symptoms on day 3 but not the severity of the overall daily symptoms.

Preventive Studies

One double-blind study in young children found that daily zinc supplementation substantially decreased the incidence of colds. The number of children who developed colds while on zinc supplements was about 40% less than the number in the placebo group (inactive medicine). Other trials also found that preventive zinc supplementation can lead to a reduction in the number of colds per cold season in children. 

In one study that enrolled elderly residents of a nursing home, those who had normal zinc levels were found to be at a lower risk of pneumonia and needed fewer antibiotic prescriptions and fewer days of treatment with antimicrobial agents. Authors suggested that older individuals with low serum zinc may benefit from zinc supplements. 

Mixed Results and Ongoing Research

The results of research on zinc and the common cold are mixed. Systematic review and meta analysis of studies suggest dietary supplements containing zinc are beneficial in preventing and treating colds. But studies have also found zinc supplements are ineffective and can cause uncomfortable, and even serious, side effects. 

Does Zinc Actually Help With Colds?

Zinc may help with colds, but based on current research findings, experts do not recommend zinc to prevent or treat common colds and other respiratory tract infections. This is because of low certainty evidence and unclear potential benefits as well as known side effects and health risks.

Does Zicam Really Shorten Colds?

Zicam may shorten colds by reducing the severity of individual symptoms like runny nose, stuffy nose, sore throat, or cough. 

Zicam is a brand name for a range of cold and flu remedies. Keep in mind that these are supplements that contain ingredients such as zinc, vitamin C, and vitamin D. The claims that Zicam shortens colds are based on traditional homeopathic medicine and are not accepted medical evidence. Some of the studies on supplements are sponsored by the pharmaceutical companies that make them. Zicam products are dietary supplements, and these claims have, therefore, not been evaluated by the U.S. Food and Drug Administration (FDA). 

Proper Dosage and Utilization

Recommended Daily Amounts of Zinc By Age Groups

Different age groups have different recommended daily amounts of zinc, which most often can be achieved through normal dietary intake. Zinc-rich food sources include seafood, meats, poultry, eggs, dairy products, legumes, nuts and seeds, and whole grains.

The recommended daily amount of zinc for different age groups is as follows:

• Birth to 6 months: 2 milligrams (mg) of zinc

• 7-36 months: 3 mg of zinc

• 4-8 years: 5 mg of zinc

• 9-13 years: 8 mg of zinc

• Teens (aged 14-18 years):

  • Boys: 11 mg of zinc

  • Girls years: 9 mg of zinc

  • Pregnant (14-18 years): 12 mg of zinc

  • Lactating (14-18 years): 13 mg of zinc

• Adults (19+ years):

• • Men: 11 mg of zinc

  • Women (age 19+): 8 mg of zinc

  • Pregnant: 11 mg of zinc

  • Lactating: 12 mg of zinc

Forms of Zinc Supplements

Zinc supplements contain various salts such as zinc acetate, zinc gluconate, zinc citrate, zinc picolinate, zinc glycerate, and zinc sulfate. 

Studies have not found a significant difference between zinc acetate, and zinc gluconate lozenges in terms of shortening the duration of the common cold. More research is needed to find out which kinds of zinc are the most effective against cold viruses and which kinds are least likely to cause adverse effects. If you find that one form, for example, zinc gluconate lozenges, causes an upset stomach, it might be worth trying another form, like zinc lozenges that contain zinc picolinate.

How Much Zinc to Take for a Cold?

The recommended dosage of zinc supplements for common colds ranges between 5 mg and 20 mg per dose. The maximum recommended dose is 40 mg of zinc per day for adults unless advised otherwise by a healthcare provider.

Doses ranging between 75 mg and 100 mg per day have been studied in clinical trials. In some studies, patients took zinc lozenges containing 10 mg to 24 mg of zinc gluconate every 1 to 4 hours during the day for 3 to 7 days. In other studies, the dose was zinc sulfate syrup 15 mg twice a day for 10 days. 

Best Practices for Zinc Supplementation

• Check with your doctor before taking zinc in dietary supplements and multivitamins. Interactions between zinc supplements and your other medications can put you at risk of serious side effects.

• Start zinc supplementation as soon as possible after developing cold symptoms, ideally within the first 24 hours. 

• You can take zinc supplements with water or juice. If you develop an upset stomach, taking zinc with food might help.

• Avoid taking zinc at the same time as calcium or iron supplements.

• There is a close relationship between zinc and copper. High levels of zinc in the body can lead to a copper deficiency and vice versa. Therefore, if you take zinc, experts recommend that you also take copper (both trace elements are commonly present in multivitamins).

Common Zinc Products and Their Effectiveness

Zinc supplements are available in tablet form as well as syrup, lozenges, and nasal spray. Research does not suggest that one form is better than the other in preventing or treating the common cold. Also, there are no studies comparing various forms in terms of side effects like bad taste.

Potential Side Effects and Risks

Side Effects of Zinc Lozenges and Supplements

If you plan to take supplemental zinc – whether for a cold or any other reason – it is important to discuss with your healthcare provider because zinc can cause unpleasant side effects that can be serious in some cases.

Common side effects of zinc supplements include upset stomach, loss of appetite, abdominal pain, metallic or unpleasant taste, nausea, vomiting, headaches, and mouth irritation. More serious side effects can also occur. There are reports of permanent loss of smell related to the use of zinc nasal sprays. 

Symptoms of Too Much Zinc

Excessive intake of zinc can lead to zinc toxicity, which can be dangerous and cause side effects such as nausea, vomiting, abdominal cramping, loss of appetite, diarrhea, or headache, and prolonged excessive intake of zinc can contribute to copper deficiency.

An overdose of zinc can cause headaches, dizziness, drowsiness, sweating, poor coordination, and hallucinations. Doses of 10 to 30 grams of zinc can be fatal.

Long-Term Risks of Zinc

Research suggests that doses up to 40 mg of zinc daily are safe to take in the short term. However, researchers in integrative health are not sure about safety issues and adverse events related to long-term zinc supplementation. Some of the known risks of taking zinc supplements or multivitamins containing zinc include:

• Double the risk of prostate cancer in men at doses of 100 mg zinc daily for 10 years or more.

• Weakened immunity with very high doses of zinc. 

• Low HDL (good) cholesterol and high LDL (bad) cholesterol with high doses of zinc. 

• Permanent loss of smell with the use of zinc nasal spray. 

• Possible interactions between zinc and other prescription drugs and over-the-counter medications. 

Who Should Not Take Zinc?

Children should not take zinc as a cold remedy unless advised by a healthcare provider.

Women who are pregnant or breastfeeding should check with their doctor before taking any dietary supplements, including zinc.

Zinc in Your Diet

Dietary Sources: Zinc-Rich Foods

Food sources of zinc include pork, beef, lamb, shellfish, cheese, whole grains, legumes, nuts and seeds, miso, tofu, and yeast. Zinc is also present in many multivitamins and mineral supplements. In addition, it is an ingredient in many over-the-counter cough and cold remedies, such as lozenges, nasal sprays, and nasal gels.

Dietary Reference Intakes: How Much Zinc Do You Need Per Day?

According to the National Institutes of Health, the recommended dietary allowance (RDA) for zinc in adults is 8 mg daily in females and 11 mg daily in males. Pregnant women need 11 mg/day and lactating women need 12 mg/day of zinc. Children need between 2 mg daily and 8 mg daily, depending on age. 

Signs of Zinc Deficiency

Zinc deficiency is rare in developed countries such as the United States. Signs and symptoms of low zinc levels in the body may include frequent infections, hair loss, loss of appetite, problems with taste and smell, slowed growth, skin sores, slow wound healing, and trouble with night vision.