What is zinc?

Zinc is a mineral that is naturally found in some foods. It is also available as a dietary supplement.

Zinc is needed in our diet, because it is used by the body for many functions, including the immune system, wound healing, the ability to taste and smell, and normal growth and development of a baby during pregnancy, childhood and adolescence.

Does taking zinc help a cold?

Clinical trials have shown that zinc might shorten the length of your cold and improve your symptoms if you are generally healthy and you take zinc within 24 hours of your symptoms appearing. But these studies have not established exactly how much zinc you need to take, what form is the most effective (lozenges or syrup), or for how long you should take it.

What are the side effects of zinc?

Zinc lozenges can cause side effects like nausea or a bad taste in the mouth.

Who can I ask about side effects?

If you’re concerned that you or someone in your care may have had side effects related to a medicine, seek medical advice. People with questions about their medicines or seeking general information about side effects can also call the NPS Medicines Line on 1300 633 424 (Monday-Friday, 9am-5pm). Your call will be answered by healthdirect Australia (except Queensland and Victoria).

To report possible side effects call the Adverse Medicine Events (AME) line on 1300 134 237 from anywhere in Australia (Monday–Friday, 9am–5pm AEST).


Tell your doctor about all the medicines you are taking

It is important that you tell your health professional about all the medicines you or anyone in your care is taking — including prescription, over-the-counter and complementary medicines (‘herbal’ or ‘natural’ medicines and vitamin and mineral supplements). This is because all medicines, including herbal and natural medicines, can cause side effects and may interact with other medicines. The benefits and risks of herbal and natural medicines may not have been tested.

Zinc can interact with the following medicines and minerals:

  • calcium supplements can interfere with the absorption of zinc into your system. Take your calcium and zinc supplements at least 2 to 3 hours apart to avoid this interaction.
  • quinolones (a type of antibiotic) can bind to zinc in your stomach and bowels, which reduces absorption of the antibiotic into your system and its ability to fight your infection. Quinolones include ciprofloxacin (used for chronic otitis media; e.g. Profloxin), and moxifloxacin (used to treat pneumonia; e.g. Avelox).
  • tetracycline antibiotics can combine chemically with zinc, reducing the uptake of the antibiotic into your system and its ability to fight your infection. Take your zinc tablets and your antibiotics at least 2 hours apart to avoid this interaction. Tetracycline antibiotics include doxycycline (used to treat pneumonia; e.g. Doxy-100).

Note about medicines names

Most medicines have two names: the active ingredient and the brand name. The active ingredient is the chemical in the medicine that makes it work. The brand name is the name given to the medicine by its manufacturer. There may be several brands that contain the same active ingredient. This website uses active ingredient names (e.g. amoxycillin), with brand names in brackets and with a capital letter (e.g. Amoxil). We also discuss medicines in groups or ‘classes’ when their effects or actions are very similar.

To find out more about active ingredients and brand names read our brand choices information.

Phone for medicines information

Call NPS Medicines Line on 1300 MEDICINE (1300 633 424) to get information about your prescription, over-the-counter and complementary medicines (herbal, ‘natural’, vitamins and mineral supplements) from a pharmacist. Your call will be answered by healthdirect Australia.


Related information - zinc


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For health professionals (Health professional publication)
15 May 2014 A growing body of evidence suggests a role for oral zinc supplements – if used soon after symptom onset – to shorten the duration of the common cold. However, questions still remain about formulation, side effects, optimal dose and applicability across different patient populations.
30 Nov 2012 Doxycycline can interact with Oral retinoids (isotretinoin or acitretin, used to treat acne and tretinoin used to treat leukaemia). Find out more about the interactions with doxycycline
23 Aug 2012 Find out if complementary medicines such as vitamin C, echinacea & zinc help to treat or prevent respiratory tract infections such as coughs & colds.
30 Sep 2011 Evidence for any benefit of zinc supplements for people taking blood pressure lowering medicines ('antihypertensives') in the absence of zinc deficiency is limited