Zinc sulfate for radiation-related taste changes in head and neck cancer

Evidence Explorer · MS-N302 · Minerals · Supportive care · Appraised 11 November 2026

Trials of oral zinc sulfate for radiation-related dysgeusia are inconsistent; a large phase III trial did not show a statistically significant prevention or recovery benefit.

Evidence at a glance

Evidence label: Mixed evidence; phase III trial negative
Benefit: A meta-analysis reported fewer cases of dysgeusia, but the largest placebo-controlled trial did not demonstrate a significant benefit.
Certainty: Low to moderate: conflicting randomized trials, varied outcome measures, and imprecise estimates for recovery.
Risk: Research doses can exceed the adult upper intake level; prolonged high intake can cause copper deficiency and interact with antibiotics or penicillamine.
Goal: Prevention or recovery of taste changes; not tumor control.

What was studied

Phase III trial: 169 evaluable patients receiving head-and-neck radiotherapy were randomized to zinc sulfate 45 mg three times daily or placebo during radiotherapy and for one month afterward.

Results: Taste alteration occurred in 73% of the zinc group and 84% of placebo (p=0.16); time to onset and recovery were not significantly improved. Smaller trials have reported benefit.

Synthesis: A meta-analysis estimated reduced incidence (risk ratio 0.72, 95% CI 0.67–0.92) but no clearly faster recovery (risk ratio 2.58, 95% CI 0.97–6.88). A 2026 pilot comparison included only 16 participants and cannot resolve the uncertainty.

What this evidence cannot establish

The evidence does not establish a reliable overall benefit for every patient or every zinc formulation.

Taste recovery is a supportive-care outcome and does not indicate better tumor control or survival.

Safety and practical context

The NIH adult tolerable upper intake level is 40 mg elemental zinc daily for routine intake; medically supervised research dosing can exceed it, but prolonged doses of 50 mg or more may impair copper absorption.

Zinc can cause nausea and interfere with quinolone or tetracycline antibiotics and penicillamine when taken too close together.

Questions for the care team

How much elemental zinc does the product contain?
Will copper and blood counts need monitoring if use is prolonged?
Could zinc interfere with antibiotics or other medicines?

Sources and identifiers

Funding and conflicts: The phase III study received U.S. National Cancer Institute support; other trial funding varied.

Source access: Original reports, abstracts/full text where available, registries and authoritative safety sources checked 11 November 2026. Primary abstracts and the systematic review abstract were appraised.

This educational evidence record is not a personal treatment recommendation. Symptom or toxicity findings do not establish tumor response, delayed recurrence or longer survival; laboratory and animal findings are not proof of clinical benefit.