Zinc lozenges are oral supplements that dissolve slowly in the mouth, releasing ionic zinc to the throat and upper respiratory tract. They are marketed for reducing the duration and severity of common cold symptoms. Unlike standard zinc tablets used for nutritional supplementation, lozenges are formulated to maintain local zinc concentrations in the oropharynx. Some research suggests zinc ions may interfere with viral replication and support immune function, though evidence remains mixed. In the UK, most zinc lozenges are regulated as food supplements rather than licensed medicines, and they are not routinely recommended by NICE or the NHS for treating colds.

What Are Zinc Lozenges and How Do They Work?

Zinc lozenges are oral supplements designed to dissolve slowly in the mouth, releasing ionic zinc that comes into direct contact with the throat and oral mucosa. Unlike standard zinc tablets taken for nutritional supplementation, lozenges are formulated specifically to maintain local zinc concentrations in the upper respiratory tract during the dissolution process, which typically takes 15–30 minutes per lozenge.

The proposed mechanism of action relates to zinc's potential antiviral properties. Laboratory studies suggest that zinc ions may interfere with viral processes, potentially inhibiting rhinovirus replication in laboratory settings. Research indicates zinc might help prevent viral particles from binding to cells in the nasal epithelium and may reduce viral shedding, though these effects are not fully established in humans. Additionally, zinc plays a recognised role in immune function, supporting the activity of natural killer cells and the production of interferon-gamma.

Commercially available zinc lozenges typically contain zinc acetate or zinc gluconate as the active ingredient, with doses ranging from 9–25 mg of elemental zinc per lozenge. The formulation matters considerably: certain additives such as citric acid, tartaric acid, or EDTA can bind zinc ions and reduce their bioavailability, potentially diminishing therapeutic effect. For this reason, products are often formulated to maintain ionic zinc in a free, active state.

In the UK, most zinc lozenges are regulated as food supplements or medical devices rather than licensed medicines. It is important to distinguish zinc lozenges from other zinc-containing products. Intranasal zinc preparations have been associated with anosmia (loss of smell) and are not recommended. Zinc lozenges work through a different mechanism—local oropharyngeal exposure rather than nasal application—and have a distinct safety profile when used appropriately.

Evidence for Zinc Lozenges in Treating the Common Cold

The evidence base for zinc lozenges in common cold treatment has been examined through numerous randomised controlled trials and systematic reviews, with results showing both promise and variability. A Cochrane systematic review analysed multiple trials and found that zinc lozenges, when initiated within 24 hours of symptom onset, may reduce the duration of cold symptoms by approximately one to two days in otherwise healthy adults. However, the quality of evidence was rated as moderate due to heterogeneity in study designs, formulations, and dosing regimens.

Several well-designed trials have demonstrated statistically significant reductions in cold duration. Studies using zinc acetate lozenges at total daily doses of 80–92 mg of elemental zinc showed the most consistent benefits, with some participants experiencing symptom resolution up to three days earlier than placebo groups. These research-based dosing regimens are higher than typical daily supplementation and should not be confused with standard nutritional recommendations. The effect appears most pronounced when treatment begins early—ideally within the first 24 hours of symptom onset—and continues throughout the symptomatic period.

However, not all studies have shown positive results. Trials using lower zinc doses, different formulations, or those with methodological limitations have failed to demonstrate significant clinical benefit. The variability in findings may relate to differences in zinc salt composition, the presence of zinc-binding compounds in formulations, baseline zinc status of participants, and the specific viral strains causing infection. Evidence for effectiveness in children and for preventive use remains inconsistent and insufficient.

Currently, there is no official endorsement from NICE or the NHS for zinc lozenges as a recommended treatment for the common cold, reflecting the mixed evidence base and the self-limiting nature of the condition. Healthcare professionals should counsel patients that whilst some evidence supports potential benefit, zinc lozenges are not a cure and effects, when present, are modest.

How to Use Zinc Lozenges Effectively

For individuals choosing to use zinc lozenges, proper timing and dosing are important to maximise potential benefit. Treatment should ideally commence within 24 hours of the first cold symptoms—such as sore throat, nasal congestion, or malaise—as delayed initiation appears less effective. Lozenges should be dissolved slowly in the mouth rather than chewed or swallowed whole, allowing sustained contact between ionic zinc and the oropharyngeal mucosa.

Research studies have typically used regimens involving one lozenge every 2–3 hours whilst awake, with total daily elemental zinc intake ranging from 75–100 mg. This usually translates to 5–8 lozenges per day, depending on the zinc content per lozenge. However, you should always follow the specific instructions on your product label rather than research protocols, as formulations vary considerably. Treatment should continue throughout the symptomatic period but generally should not exceed 7–10 consecutive days.

Important practical considerations include:

• Allow each lozenge to dissolve completely in the mouth (15–30 minutes)

• Avoid eating or drinking for 15 minutes after the lozenge has dissolved

• Do not exceed the recommended daily dose stated on the product

• Discontinue use once cold symptoms have resolved

• Check product labels for zinc-binding additives that may reduce efficacy

Zinc lozenges are intended for short-term use only during acute illness. Long-term or excessive zinc supplementation can lead to copper deficiency, immune dysfunction, and other adverse effects. The UK Expert Group on Vitamins and Minerals has established a Safe Upper Level for zinc of 25 mg daily from supplements for long-term use, though short-term therapeutic doses for colds are higher and considered acceptable for brief periods when following product instructions.

If you are taking medications, be aware that zinc can interact with certain antibiotics. Separate zinc lozenges from tetracyclines by at least 2–3 hours and from fluoroquinolones by at least 4 hours. Zinc may also interact with penicillamine and other chelating agents. Consult a pharmacist if you are unsure about potential interactions.

Zinc lozenges are generally not recommended for young children due to potential choking hazards and the risk of exceeding safe intake levels. Always check age restrictions on product packaging.

Side Effects and Safety Considerations

Whilst zinc lozenges are generally well-tolerated for short-term use, several adverse effects have been consistently reported in clinical trials. The most common complaint is an unpleasant taste, described as metallic or bitter, which affects a substantial proportion of users and may limit adherence to treatment regimens. This taste disturbance is typically temporary and resolves after discontinuation but can be bothersome during the treatment period.

Gastrointestinal symptoms represent another frequent concern. Nausea is reported by approximately 10–20% of users in clinical studies, and some individuals experience mouth irritation, dry mouth, or oral discomfort. Taking lozenges on an empty stomach may exacerbate nausea, though the intended use requires dissolution in the mouth rather than ingestion with food. These effects are generally mild and self-limiting but may prompt some patients to discontinue treatment prematurely.

More significant safety considerations relate to prolonged or excessive use. Chronic high-dose zinc supplementation can interfere with copper absorption, potentially leading to copper deficiency anaemia, neutropenia, and neurological complications. For this reason, zinc lozenges should not be used continuously beyond the duration of cold symptoms or as a preventive measure without medical supervision.

Specific populations require additional caution:

• Pregnant and breastfeeding women should consult healthcare providers before use

• Individuals with existing copper deficiency, anaemia, or renal impairment should avoid high-dose zinc

• Those taking antibiotics (particularly tetracyclines or fluoroquinolones) should separate administration as advised above

• Patients on penicillamine or other chelating agents may experience drug interactions

Intranasal zinc preparations warrant particular mention: these have been associated with permanent anosmia and should be avoided entirely. This risk does not apply to oral zinc lozenges, which work through a different mechanism.

If you experience any suspected side effects from zinc lozenges, you can report them through the MHRA Yellow Card Scheme (yellowcard.mhra.gov.uk). Patients experiencing persistent symptoms beyond 3 weeks, high fever, severe headache, or difficulty breathing should seek medical assessment, as these may indicate complications requiring specific treatment.

Alternatives and When to Seek Medical Advice

For individuals seeking symptomatic relief from the common cold, several evidence-based alternatives exist alongside or instead of zinc lozenges. Paracetamol or ibuprofen remain first-line recommendations for managing fever, headache, and myalgia associated with upper respiratory tract infections. These analgesics have well-established safety profiles and provide reliable symptomatic benefit, though they do not shorten illness duration. Ibuprofen should be used with caution in people with certain gastrointestinal, cardiovascular, or kidney conditions; speak to a pharmacist if unsure.

Other supportive measures with varying levels of evidence include adequate hydration, rest, and humidified air to ease nasal congestion. Honey (in adults and children over 12 months) has some evidence for reducing cough frequency and severity, as recognised in NICE guidance. Vitamin C supplementation shows minimal benefit for treatment but may slightly reduce cold duration in individuals under extreme physical stress. Echinacea preparations have mixed evidence, and NICE does not recommend them routinely. Decongestants and antihistamines may provide short-term symptomatic relief but should be used judiciously and for limited periods.

The common cold is typically self-limiting, resolving within 7–10 days without specific treatment. However, certain circumstances warrant medical assessment:

• Symptoms not improving after 3 weeks or worsening after initial improvement

• High fever lasting more than 5 days or recurring after initial resolution

• Severe or persistent headache, particularly with neck stiffness or photophobia

• Difficulty breathing or significant shortness of breath (call 999 if severe)

• Chest pain (call 999 if severe)

• Productive cough with purulent sputum, especially if blood-stained

• Earache or facial pain suggesting sinusitis or otitis media

• Underlying health conditions such as asthma, COPD, immunosuppression, or cardiovascular disease

Patients should contact their GP or NHS 111 if they experience concerning symptoms or if they are uncertain about the severity of their illness. Vulnerable populations—including young children, elderly individuals, and those with chronic conditions—may require earlier assessment. Whilst zinc lozenges and other over-the-counter remedies may offer modest symptomatic benefit for some individuals, they do not replace clinical judgement when complications arise or when symptoms suggest a condition requiring specific medical intervention.

Frequently Asked Questions