Excipients in medicines

Excipients or inactive ingredients in medicines

Key points about excipients in medicines

  • Excipients are extra substances found in medicines such as fillers.
  • They are often referred to as inactive ingredients.
  • Read about excipients in medicines including why they are added to medicines.
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Prescription and over the counter (OTC) medicines are made up of many ingredients. The part of the medicine that makes it work is known as the active ingredient, but inactive ingredients or ‘excipients’ are also added.

Different medicines contain different excipients. Read more below about how to find out which excipients are in your medicines

Excipients are added to medicines for different reasons, for example:

  • To improve the taste – sugar, artificial sweeteners or flavouring may be added to make them taste better.
  • To improve the texture – thickening agents may be added to make liquid medicines easier to pour.
  • To dissolve the medicine – small amounts of ethanol (alcohol) may be used to help dissolve a liquid into a liquid form.
  • To make them easier to handle – powders or fillers can be used to make tablets large enough to handle if the amount of active ingredient is very small.
  • To make them work better – extra ingredients may be added to tablets to help them break down properly in your stomach.
  • To make them last longer – preservatives might be added to improve the shelf-life of a medicine.

If you need to avoid any excipients, tell your pharmacist when you're starting a new medicine or brand. Different brands of the same medicine may use different excipients, especially preservatives and colourants, so there could be another option available.

Different medicines contain different excipients. All medicines approved in Aotearoa New Zealand have been assessed by Medsafe, which includes reviewing the excipients to ensure they meet their quality and safety standards. 

Some people may want to avoid some excipients. Tell your doctor or pharmacist if you need to avoid an excipient, as they may be able to provide a different version of the medicine. Note, most medicines have very small amounts of excipients that are unlikely to cause any problems.

Tell your pharmacist if you need to avoid any of the following excipients
  • Peanut oil (also called Arachis): If you're allergic to peanuts, tell your pharmacist so that a different medicine or brand can be provided.
  • Soya oil: If you're allergic to peanuts, you may also be allergic to soya. Tell your pharmacist so that a different medicine or brand can be provided.
  • Aspartame: This is a sweetener used instead of sugar. People who have phenylketonuria should avoid aspartame because it is converted to phenylalanine in the body.
  • Gluten: Most medicines are gluten-free. However, some medicines may contain wheat starch, which people with coeliac disease need to avoid. See gluten in medicines.
  • Colourings: Medicines may contain colouring agents that some people are sensitive to. Colour-free forms are available for some medicines.
  • Sugar: People with diabetes need to be aware of sugars in medicines. Sugar-free forms may be available.
  • Preservatives: Preservatives (eg, parabens  – also known as methyl, ethyl or propyl hydroxybenzoates) have been linked to potential allergic reactions. Some preservatives need to be avoided in very young and premature babies, eg, sodium benzoate. 

The following excipients are unlikely to cause any problems but some people may prefer to avoid them.


People with some conditions may need to avoid medicines containing lactose. These are rare and include galactose intolerance, total lactose deficiency or glucose-galactose malabsorption. The amount of lactose in tablets is very small, and it's unlikely to have an effect for people who are lactose intolerant.


Ethanol (the scientific name for alcohol) may be used to help a medicine dissolve to make a liquid medicine. Medicines for children don't contain ethanol. Adult medicines may contain it, but the amount is usually very small.

Propylene glycol

This is another form of alcohol, now rarely used. If your medicine contains it you should talk to your doctor or pharmacist before giving the medicine to any child under 5 years of age.

Animal-derived excipients

Some excipients, eg gelatin, are derived from animal products which vegetarians, vegans and people of particular faith may wish to avoid. Gelatin is sometimes used as the coating of capsules. Lactose is typically from animal milk.

Mannitol and sorbitol

These are artificial sweeteners used in sugar-free forms of medicines. These can cause soft or runny poos (diarrhoea), but as only a small amount is present in medicines, it's unlikely to be a problem.

If you would like to know which excipients are in your medicine, your healthcare provider or pharmacist will be able to help you. You can usually find information about excipients in the following places.

Medicine boxes or packaging

For medicines released to the Aotearoa New Zealand market from 1 March 2024, there will be a warning statement on the medicine box or packaging for some excipients. If the medicine container is small, the warning statement will be on the information leaflet inside the container instead.

List of excipients (inactive ingredients) used in medicines

Image credit: Medsafe NZ

Consumer medicine information (CMI)

If there's a consumer leaflet for your medicine, excipients are listed in the ‘Ingredients’ section near the end of the leaflet. You can also search for the CMI on the Medsafe website(external link).

Data sheet (prescribing information)

The medicine data sheet (prescribing information) lists the excipients in the ‘Pharmaceutical Particulars’ section near the end of the data sheet. You can search for the data sheet on the Medsafe website(external link).

Product/Application search

If your medicine doesn't have a CMI or a data sheet, you can use Medsafe’s online Product/Application search:(external link)

  • Enter the medicine’s brand name in the ‘Trade name’ box. Click on the relevant search result to view the excipients in that medicine.
  • To find out which medicines contain any excipient, enter the excipient in the ‘Ingredient’ box. The search results list all the medicines containing that excipient.

Contact the pharmaceutical company

There may be some information about your medicine that only the pharmaceutical company can provide. This may include:

  • ingredients within a flavour or colour
  • manufacturing impurities or contaminants
  • components of an ingredient (eg, caffeine in a natural health product)
  • the source of an ingredient (eg, whether it comes from an animal).

Look for the company contact details on the medicine packaging, or at the end of the data sheet, CMI or Product/Application search.


5 questions to ask about your medications
5 questions to ask about your medications

Health Quality and Safety Commission, NZ, 2019

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Credits: Sandra Ponen, Pharmacist, Healthify He Puna Waiora. Healthify is brought to you by Health Navigator Charitable Trust.

Reviewed by: Angela Lambie, Pharmacist, Auckland

Last reviewed: