Defining excipients
Excipients are the substances other than the active ingredient (drug), which make up a medicine. They have specific purposes such as:
- improving taste and texture of the medicine
- aiding the manufacturing process
- improving the overall safety or function of the product
Most excipients have no pharmacological action, in other words they are inactive. However, some excipients may have a known action or effect in certain circumstances.
The European Medicines Agency (EMA) guidance on labelling of excipients lists excipients with known action or effect and provides information on safe limits. These excipients must feature in the product information for the medicine. This includes the Summary of Product Characteristics (SmPC) and the Patient Information Leaflet (PIL).
Impurities and residues
Impurities and residues arising from manufacturing processes are not considered to be excipients.
With vaccines, residues of clinical relevance are mentioned in the product information. Examples include traces of antibiotics or host cell proteins. Other impurities and residues are not required to be listed in the product information.
Sometimes the manufacturer may not guarantee the absence of a trace substance such as latex. This may be due to contact with other products during the manufacturing process. Review and decide clinical use on a case-by-case basis by balancing the potential risk against the benefit.
Checking for presence of excipients
You may want to check what excipients are present in a medicine or may want to find a medicine free from a specific excipient. Medicines produced by different manufacturers or different strengths of a medicine may contain different excipients. You can check presence of an excipient for licensed medicines in the SmPC and PIL.
These documents are available from:
Our guidance on searching for presence or absence of an excipient in medicines provides support on how to find a medicine that is free from a specific excipient.
As manufacturers may change the formulations of their product it is important that individuals confirm that a product is free from the required excipient at the point of dispensing or sale.
If it is essential to avoid a specific excipient for example, due to severe allergy, you should consider contacting the manufacturer to confirm suitability.
Medical devices and food supplements
Medical devices and food supplements, such as vitamins and minerals may not have a SmPC. Contact the manufacturers directly for advice.
Understanding complementary medicines provides further information on the regulations of complementary medicines including food supplements.
Unlicensed or imported medicines
Unlicensed or imported medicines may not include full details of excipients and this information may be difficult to find. The product information may not be in English. Seek clarity relating to excipients from the manufacturer and/or importing company.
Reasons to avoid particular excipients
In certain scenarios, some people may need to avoid particular excipients due to allergies, age or co-existing medical conditions. Others may want to avoid particular excipients due to lifestyle considerations or religious beliefs.
Allergies
Some people may have an allergy to a certain excipient used in medicines, for example, polyethylene glycol (PEG). Consider whether it is an intolerance or a true allergy. Confirm the nature of the reaction and severity. If confirmed as a true allergy, ensure the allergy and nature of the reaction is added to the person’s medical records to prevent further exposure.
Recommended resources
The following resources may be helpful:
- Allergy UK has a range of information to support people with allergies and healthcare professionals
- Anaphylaxis UK has a factsheet on excipients in cosmetics, personal care products and medicines
- British Society for Allergy & Clinical Immunology has information on vaccines and food allergy
- Coeliac UK provides information on gluten or wheat allergy
- EMA guidance on labelling of excipients has a list of excipients with known effects and additional details on background information
- MHRA alerts may identify high risk products such as the risk of peanut/soya allergy in an unlicensed vitamin D product
- SPS Prescribing in lactose intolerance and how to identify lactose free medicines provides background on the impact of lactose in medicines for those with lactose intolerance
Lifestyle considerations
People may want to avoid certain excipients due to dietary preference, ethical, cultural or religious beliefs.
Some people may wish to avoid excipients of animal origin for example, gelatine derived from the collagen of animals and lactose derived from animal milk. Contact the manufacturer directly if the source of excipient is not listed in the product information. Those wishing to avoid animal products should consider the origin of the active ingredients alongside the excipients.
Recommended resources
The following resources may be helpful:
- Culture, spirituality and religion: migrant health guide provides information on how beliefs and practices can influence perspectives on health
- European Vegetarian Union has definitions of vegan and vegetarian along with additional information
- Kosher London Beth Din provides guidance on medicines and specific formulations approved for Pesach (Passover)
- British Islamic Medical Association has practical information ranging from Ramadan compendium to vaccinations
- SPS Excipients has guidance on prescribing in lactose intolerance, considerations for vegan patients and sodium content
- UK Health Security Agency Vaccines and porcine gelatine has information about gelatine in vaccines and alternatives
- Vegan Society provides a statement regarding medicines use for vegans
Medical conditions
Some people may need to avoid certain excipients due to a medical condition such as phenylketonuria. Another example is some people are recommended by a specialist to follow a ketogenic diet who will need to restrict carbohydrate intake as much as possible in medicines.
People with conditions associated with sodium retention, such as hypertension, heart failure or renal impairment will need to review medicines containing high levels of sodium.
Recommended resources
The following resources may be helpful:
- BNF guidance on prescribing has general advice on excipients
- BNF nutrition in special diets has information on excipients for specific conditions
- British Inherited Metabolic Diseases Group has guidelines and information on excipients to avoid in certain metabolic disorders
- Matthews Friends has information to support people on ketogenic diets
- Metabolic Support UK has information on excipients that can cause harm in metabolic disorders
- SPS information on assessing suitability of medicines in a ketogenic diet
Paediatrics
Some excipients may be present in quantities which can potentially cause adverse effects or harm to neonates and children. Neonates are particularly vulnerable to harm.
Excipients may be harmful in paediatrics due to differences in pharmacokinetics and pharmacodynamics. Other reasons why excipients can be an issue are off-label use of liquids designed for adults or use of an unlicensed medicine.
Examples of excipients of concern include ethanol, propylene glycol and colouring agents.
Recommended resources
The following resources may be helpful:
- BNFC guidance for prescribing includes information on excipients
- BNFC nutrition in special diets has information on excipients
- EMA has background information on specific excipients including labelling limits
- NPPG Choosing an oral liquid medicine for children has advice on specific excipients along with recommended safe amounts and how to calculate these limits
- MedicinesforChildren– includes information on excipients and has individual medicine monographs
- MHRA has information on chloramphenicol eye drops containing borax or boric acid buffers for children under 2 years
- Pharmaceutical Journal has published an article on how to identify and manage ‘problem’ excipients in medicines for children (subscription required)
- SPS Managing the risks of using liquid oral phenobarbital has guidance on risks and mitigations with using liquid phenobarbital
- STEP Database provides in-depth information on safety and toxicity of excipients for paediatrics (registration required)
Further information
If relevant information is not available on the SPS website or the information resources listed, or if your clinical scenario is complex, we suggest you seek further advice.
Primary care healthcare professionals can get in touch with the SPS Medicines Advice service.
Secondary care healthcare professionals can contact the local medicines information service or clinical pharmacist for further support.
Update history
- Link to SPS article on assessing suitability of medicines in a ketogenic diet added to medical conditions section.
- Published