Taking high doses of zinc for a cold may help you feel better faster. Studies show taking 75 mg to 100 mg of zinc daily at the first sign of a cold can shorten its duration by about two days.
Zinc may also reduce the intensity of cold symptoms as early as day three. However, high doses of zinc can also cause unpleasant side effects, including dizziness, headaches, loss of appetite, and an upset stomach. Anosmia (loss of smell) and loss of taste also can occur.
This article discusses zinc for colds. It explains the potential benefits of zinc against the common cold and other viruses, how much zinc to take for a cold, and signs of zinc toxicity. It also lists medications that may negatively interact with zinc.
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Verywell / Danie Drankwalter
Benefits of Zinc for Colds
Researchers have examined the role of zinc in preventing and treating the common cold for the past four decades.
The original research on zinc for colds, published in 1984, found high doses of zinc shortened the common cold by about seven days. Since then, results have been less favorable but still show zinc has statistically significant benefits against the common cold.
The most comprehensive research review to date involved 5,446 participants in 28 randomized controlled trials. When compared to a placebo, the study found zinc:
- Shortened the duration of cold symptoms by an average of two days.
- Significantly reduced the severity of cold symptoms.
- Prevented five respiratory tract infections per 100 person-months.
How Does Zinc Work for Colds?
How zinc works to fight the common cold is not fully understood. However, researchers note that zinc ions inhibit the replication of common viruses. Its ability to slow viral replication may explain how zinc fights colds in the following ways:
- Prevents colds: Cold viruses replicate the fastest before symptoms begin. Taking zinc throughout cold season has been shown to help prevent up to 11% of colds.
- Shortens colds: Once symptoms appear, the virus continues to replicate for a few days. This may explain why taking zinc at the first sign of a cold can help it heal three times faster.
- Eases cold symptoms: Symptom severity is associated with viral load. Inhibited viral replication means a lower viral load and, therefore, less severe symptoms. One study found a significant reduction in cold symptoms by the third day, which is when symptoms typically intensify.
Zinc supports a healthy immune system. After iron, it is the second most common essential mineral in our bodies. But because our bodies can't make zinc, we have to get what we need from food or supplements.
How to Take Zinc for Colds
Zinc supplements come in different forms. The lozenges are commonly used to treat colds.
The sooner you start taking zinc for a cold, the better the results—ideally within 24 hours of the first sign of a cold. In studies, people who were given zinc at the earliest sign of a cold had the most notable results.
How Much Zinc to Take for a Cold
The amount of zinc required to help fight off a cold is not firmly established. The recommended daily amount of zinc is 8 mg for adult women and 11 mg for adult men. However, higher doses are used to treat colds.
The overall recommendation is 75 mg to 100 mg of zinc divided into multiple doses throughout the day. Some researchers pinpoint the optimal range as 80 mg to 92 mg. Taking more than 100 mg of zinc a day does not offer any additional benefits.
Zinc lozenges come in different strengths with different dosing recommendations. For example:
- Cold-Eeze: Up to six 13.3 mg lozenges for a total of 80 mg of zinc a day
- Nature’s Way: Up to six 23 mg lozenges for a total of 138 mg of zinc a day
- Quantum Health: Up to 12 7 mg lozenges for a total of 84 mg of zinc a day
Zinc lozenges often contain other cold-fighting ingredients, such as vitamin C, elderberry, or echinacea. Do not take larger doses than recommended on the product label.
Stop taking high doses of zinc once symptoms resolve. Do not take high doses of zinc for longer than 14 days.
Types of Zinc Supplements
In addition to lozenges, zinc is also sold in over-the-counter (OTC) nutritional supplements as tablets, capsules, syrups, oral sprays, nasal sprays, and intranasal gels.
Zinc comes in different forms and supplements may contain one or more of the following:
- Zinc acetate
- Zinc citrate
- Zinc gluconate
- Zinc glycerate
- Zinc monomethionine
- Zinc picolinate
- Zinc sulfate
The different forms may have slightly different effects on the duration and severity of symptoms, but the research is not definitive on this point.
Zinc Side Effects
Taking high doses of zinc can cause unpleasant side effects, including:
- Abdominal cramps
- Dizziness
- Headaches
- Loss of appetite
- Nausea
- Vomiting
- Loss of smell and taste
Some forms of zinc are easier to digest than others. For example, zinc sulfate is more likely to cause stomach upset, while zinc citrate is less likely to cause gastric side effects.
Some types of zinc supplements have additional side effects, including:
- Zinc nasal sprays: Loss of smell, which can be temporary or permanent
- Zinc lozenges: Altered taste or a bad taste in your mouth
Too much zinc can also reduce the amount of copper in your body. Also an essential mineral, copper levels can be affected when taking 40 mg of zinc or more daily for extended periods of time.
Who Should Not Take Zinc?
High doses of zinc may not be safe for people with a copper deficiency and those who are pregnant or breastfeeding. Be sure to talk with your healthcare provider about underlying health conditions, such as impaired kidney function, and any medications that you take.
Drug Interactions
Zinc can also interact with certain medicines, including:
- ACE inhibitors (angiotensin-converting enzyme inhibitors) such as Altace (ramipril), Lotensin (benazepril), and Zestril (lisinopril)
- Certain antibiotics, including quinolone antibiotics like Cipro (ciprofloxacin) and tetracycline antibiotics like Sumycin (tetracycline)
- Certain diuretics, including Hygroton and Thalitone (both chlorthalidone) and Microzide and Esidrix (both hydrochlorothiazide)
- Cuprimine or Depen Titratabs (both penicillamine). These are used to treat Wilson's disease and rheumatoid arthritis, and zinc should not be taken within two hours of them. It can decrease the absorption of penicillamine.
- Midamor (amiloride)
- Antiviral medications used to treat human immunodeficiency virus (HIV)
If you take any of these medications, talk to your healthcare provider or pharmacist before taking zinc supplements.
What Foods Are High in Zinc?
If you eat a balanced diet, you should have sufficient zinc for your body to function properly. If you want to eat foods high in zinc when you feel a cold coming on, some options include:
- Oysters
- Beef
- Beans
- Crab
- Dairy products
- Fortified cereals
- Lobster
- Peanuts
- Pork
- Pumpkin seeds
- Shrimp
- Whole grains
Most people get enough zinc from food in their normal diet. The body does not store zinc, and it eliminates what it does not need or use.
A Word From Verywell
When I advise my patients on how to start treating a common cold, I always recommend zinc, but it’s only one component. I emphasize that treating the first symptoms is what really matters (with any type of symptom, such as sore throat or runny nose). Treating early with all the over-the-counter tools is the key to preventing disease progression, avoid complications, and achieve earlier resolution.
Summary
Taking zinc supplements at the first sign of a cold may help to relieve symptoms faster. It works best when taken within 24 hours of symptom onset, usually as a lozenge or nasal spray.
How much zinc to take for a cold ranges from 75 mg to 100 mg a day, divided into multiple doses. There is no standard agreement on the optimal dose. Studies show no added benefit in taking more than 100 mg a day.
Side effects of zinc are more common with higher doses and include dizziness, nausea, abdominal pain, and vomiting. Zinc supplements may also negatively interact with certain medications, including some antibiotics, diuretics, and ACE inhibitors.
Before taking zinc supplements, talk to your healthcare provider. Follow the package direction and do not take more than the recommended dose.