Zinc for Colds: How It Works & What Studies Show

Zinc is one of 16 essential trace minerals your body needs for optimal health. Next to iron, it is the most abundant mineral in your body and is found in almost every cell. Zinc is central to the proper functioning of more than 300 enzymes and is essential for proper growth and development.

One of Zinc's prime uses comes in boosting the immune system. People who are deficient in Zinc are more susceptible to infections. Zinc supplementation improves immune system function, helping protect against colds and upper respiratory illnesses. Interest in using Zinc for colds began with a serendipitous clinical observation: the cold symptoms of a 3-year-old girl with leukemia disappeared within a few hours when she allowed a Zinc tablet to slowly dissolve in her mouth instead of swallowing it whole.

That observation launched decades of research confirming Zinc's role in supporting the body's natural defenses during cold and flu season. Virtually all aspects of innate and adaptive immunity — from neutrophils and natural killer cells to T cells and B cells — are affected by Zinc status.

For more than 50 years, it has been known that Zinc deficiency compromises immune function. A network based on ZnT and ZIP proteins for transport and metallothionein for storage tightly regulates Zinc availability throughout the body. In vivo, Zinc deficiency alters the number and function of neutrophil granulocytes, monocytes, natural killer (NK) cells, T cells, and B cells. T cell functions and the balance between different subsets are particularly susceptible to changes in Zinc status.

Zinc also exerts anti-inflammatory action: Zn²⁺ can reversibly inhibit membrane phosphodiesterase (PDE) and reduce PDE mRNA expression, which decreases the production of the inflammatory cytokines tumor necrosis factor (TNF)-alpha and interleukin (IL)-1 beta. Zinc supplementation in vivo has been shown to protect mononuclear cells against oxidative stress. This anti-inflammatory mechanism may partly explain why Zinc for colds appears to reduce both the severity and duration of symptoms.

Research also suggests that Zinc has antiviral activity, supporting interferon signaling against RNA viruses and inhibiting viral RNA-dependent RNA polymerase activity. These multiple mechanisms — immune cell support, anti-inflammatory action, and antiviral defense — work together to promote the body's natural response during upper respiratory infections.

Multiple meta-analyses confirm that Zinc may meaningfully shorten cold duration. In seven randomized controlled trials, Zinc acetate and Zinc gluconate lozenges containing more than 75 mg/day of elemental Zinc shortened common cold duration on average by 33% (95% CI: 21%–45%, P = 10⁻⁷). Another meta-analysis reported no difference in efficacy between Zinc acetate and Zinc gluconate lozenges in treatment of colds.

A Cochrane review of 34 randomized trials including 8,526 patients reported that Zinc may have a benefit in treatment of colds, though it showed little to no benefit in cold prevention. A separate meta-analysis including 28 trials (5,446 participants) reported that symptoms resolved approximately 2 days earlier compared to placebo and that more subjects were likely to remain symptomatic after 7 days without Zinc.

A 2015 meta-analysis of 3 RCTs using 80–92 mg/day Zinc acetate confirmed significant reductions in specific cold symptoms: nasal discharge (34%), nasal congestion (37%), cough (46%), and hoarseness (43%). The NCCIH and AAFP both recognize Zinc as an effective treatment approach for cold symptoms in adults. Benefits appear to be dose- and formulation-dependent, with evidence strongest when Zinc is initiated within 24 hours of symptom onset.

Beyond Colds: Broader Respiratory Support

Research suggests Zinc may also support broader respiratory health. Studies have shown Zinc supplementation (20 mg/day) may accelerate recovery from severe pneumonia in children, and multiple systematic reviews support Zinc's role in reducing pneumonia and respiratory tract infection incidence, particularly in elderly populations and children.

Zinc for colds may be particularly relevant for individuals who are at higher risk of Zinc deficiency or who experience frequent upper respiratory infections. Certain populations may be at greater risk for Zinc deficiency, including people who have had gastrointestinal surgery such as weight loss surgery, people with digestive disorders such as ulcerative colitis or Crohn's disease, vegetarians (researchers have suggested that Zinc needs of vegetarians may be up to 50% higher due to phytate in plant foods), and older adults — 35%–45% of adults aged 60 years or older had Zinc intakes below the estimated average requirement.

Men may also benefit from Zinc supplementation for additional reasons beyond immune support. The hormone testosterone requires Zinc for its production, and infertility resulting from low testosterone levels may respond to increased Zinc intake. Symptoms resulting from an enlarged prostate or benign prostatic hyperplasia (BPH) may also be supported with additional Zinc.

Individuals facing surgery are encouraged to take sufficient Zinc, vitamin A, and vitamin C before and after surgery, as studies show that taking sufficient amounts of these nutrients may help optimize wound healing. Because of its immune-supporting capabilities, Zinc has also shown benefit in supporting the body's response to Candida or yeast infection in women, an effect that may be enhanced by combining Zinc with vitamins A, C, and E.

Take one (1) tablet daily with meals. Store in a cool, dry place and away from direct light. Each tablet contains 20 mg of OptiZinc®.

The Recommended Dietary Allowance (RDA) for Zinc is 8 mg/day for women and 11 mg/day for men. The Tolerable Upper Intake Level (UL) for adults is 40 mg/day. Taking supplements that contain a substantial amount of iron (≥25 mg) at the same time as Zinc supplements can reduce Zinc absorption and plasma concentrations of Zinc.

This product is gluten free, dairy free, soy free, and grain free.

Important Interactions to Be Aware Of

Zinc may interact with certain medications. Both quinolone antibiotics (such as Cipro) and tetracycline antibiotics might reduce the amount of both Zinc and the antibiotic that your body absorbs — take the antibiotic at least 2 hours before, or 4 to 6 hours after, taking a Zinc supplement. Penicillamine (used for rheumatoid arthritis and Wilson disease) absorption can be reduced by Zinc — take them at least 1 hour apart. Thiazide diuretics increase urinary Zinc excretion by as much as 60%.