Guidance

Substances recognised as medicinal by function in veterinary medicines

List of substances recognised as medicinal by function.

From:
Veterinary Medicines Directorate
Published:Published
14 January 2026
Last updated:
25 September 2026 — See all updates

This is part of a guidance collection and should be read in association with Advertising[new non-medicinal veterinary products.guidance].

The following is a list of substances recognised as medicinal by function. Some have established limits below which they are considered non-medicinal.

The notes section in this list is currently under review. We expect to publish the updated version by the end of October 2026

Any product applied to an animal that contains a substance on this list is considered medicinal by function unless that substance is below anythe stated limit.

Unless otherwise stated in this list, any product containing an active substance present in an authorised veterinary medicine as presented on the VMD’s Product Information Database is considered medicinal by function.

This list is not exhaustive.

Substance Notes
Acacia catechuApoptotic and NSAID. Medicinal by function at any level
Acetylcysteine / N-Acetylcysteine MedicinalMucolytic, medicinal at any level
Adelmidrol MedicinalALIAmide drug, medicinal at any level
Adenosylmethionine (aka SAMe) Considered Medicinal by Function in any product presented for effects on mood, liver or joint health
AttapulgiteThe inclusion of this substance in a “supplement” serves no nutritional purpose, its sole documented effect is to bind pathogenic material in the digestive tract. Orally administered products containing attapulgite are considered medicinal by function
Belladonna Medicinal at any level
BenzoylBenzalkonium PeroxideChloride Medicinal inwhen aincluded productin presentedany totopical treatproduct bacterial skin infections at a concentration exceeding 2.5%0.02%
Benzoyl PeroxideMedicinal at any level
Bismuth Sub Carbonate Medicinal by function when orally administered
Bloodroot (sanguinaria canadensis) extractSanguinarine is an escharotic and therefore medicinal by function
Bronopol Medicinal butby permittedfunction. Permitted as a preservative in leave-on and rinse-off topical products at concentrations not exceeding 0.1%
Boric Acid Medicinal by function when included at levels exceeding Talc - 5% Oral hygiene – 0.5% All other products – 3% Products containing this substance require the warning “Do not use on damaged skin”
CamphorTopical use only: Medicinal by function in product exceeding 4%
Cannabidiol (CBD) Whether as CBD isolate, or in the form of “broad spectrum” or “full spectrum” hemp plant oil. Medicinal by function at any level
Cannabigerol (CBG) Medicinal.Medicinal by function. Metabolises into CBD
Capsaicin Medicinal by function when applied topically at concentrations exceeding 0.012% due to analgesic effects
Cetylpyridinium ChlorideMedicinal by function in oral hygiene products for cat and dogs exceeding 0.0012% concentration
Chlorhexidine Gluconate Medicinal by function when applied to intact skin at concentrations exceeding 4%, or when included in first aid products at concentrations exceeding 0.3%
Colostrum MedicinalManufactured whencolostrum, including that from cows that have been treated to ensure the colostrum will contain specificparticular antibodies.antibodies, require an MA. A colostrum or colostrum-based product containing pure colostrum isdoes not medicinal,require an MA, provided that no reference is made to disease, immunoglobulin content, antibodies, IgA, IgG, or the immune system
Copper NaphthenateMedicinal by function at any level
Diazolidinyl UreaTopical use only: Medicinal by function at concentrations exceeding 0.5%
Dibenzoyl PeroxideTopical use only: Medicinal by function at concentrations exceeding 2.5%
DichlorophenTopical use only: Medicinal by function at concentrations exceeding 0.5%
Diflubenzuron Medicinal by function at any level
DMDM hydantoinTopical use only: Medicinal by function at concentrations exceeding 0.6%
Foxglove (Digitalis) Medicinal by function at any level
Guanidinopropionic Acid Medicinal by function at any level
IodineTopical use only: Medicinal by function at concentrations exceeding 0.3%
Iodoform Medicinal by function at concentrations exceeding 10%
KetaconazoleTopical use only: Medicinal by function at concentrations exceeding 1%
Lactic AcidTopical use only: Medicinal by function at concentrations exceeding 5%
Methyl Salicylate (wintergreen)Topical use only: Medicinal by function at concentrations exceeding 0.25%
NicotineMedicinal by function at any level
Palmitoylethanolamide (PEA) Micronised and Ultra-Micronised PEA is medicinal.Medicinal by Function. Has anti-inflammatory and antinociceptive properties. A synthesised alternative to CBD. Unmicronised (D10 ≥3.19µm, D50 ≥21.1µm, D90 ≥62.7 µm) – Not Medicinal by function due to apparent inefficacy. Will still be medicinal by presentation where reference is notmade consideredto the properties and purposes of micronised and ultra-micronised PEA. Consequently, all reference to finer forms of PEA and its properties, effects, and uses are prohibited. No indication may be made for systems on which medicinal butPEA productsis efficacious. Products containing unmicronised PEA must be declared as such. This declaration must be readily apparent on the packaging and wherever a reference to PEA is made in the products presentation. The use of other substances to increase the absorbency of unmicronised PEA will cause the product to be medicinal by function
ParabensTopical use only: Medicinal by function at concentrations exceeding 0.25%
PhenoxyethanolTopical use only: Medicinal by function at concentrations exceeding 2%
Potassium Iodide Medicinal by function at concentrations exceeding 1% for oral use
Potassium SorbateTopical and oral hygiene use only: Medicinal by function at concentrations exceeding 0.2%
Povidone IodineTopical use only: Medicinal by function at concentrations exceeding 3%
PyrethrumMedicinal by function at any level
ResmethrinMedicinal by function at any level
Scutellaria baicalensis (Chinese Scullcap)NSAID. Medicinal by function at any level
Sodium bicarbonate Except in feeds exclusively for ruminants. Inclusion in orally administered products in concentrations greater than 1% is considered medicinal by function due to its recognised antacid activity
Thymol Medicinal by function at any level

Updates Undecylenic toAcid Topical thisuse page

only: Medicinal by function at concentrations exceeding 2%
PublishedValerian 14Root Medicinal Januaryby 2026
function at concentrations exceeding 2% LastWillow updatedBark 25(“White SeptemberWillow”, 2026 —“Willow ShowExtract”, allSalix updates

  1. Reviewedfunction andat updatedany withlevel Zinc theChloride Topical removaluse ofonly: someMedicinal substances.by Thefunction notesat sectionconcentrations ofexceeding the2.5%. listOral isHygiene subjectuse only: Medicinal by function at concentrations exceeding 0.002% Zinc Oxide Topical use only: Medicinal by function at concentrations exceeding 5% Zinc Sulphate Topical use only: Medicinal by function at concentrations exceeding 5%

Updates to furtherthis review.

    • Published 14 January 2026

    First published.

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