What are fipronil and imidacloprid?

Fipronil and imidacloprid are active substances found in veterinary medicines used to treat and prevent flea and tick infestations in cats and dogs, providing protection against parasitic diseases and helping to reduce the risk of zoonotic transmission, thereby supporting both animal and human health.

Definitions

• Authorised Veterinary Medicine – General Sales List (AVM-GSL): Medicines that can be sold without professional advice (for example, from supermarkets, pet shops, online stores)
• SQP: Suitably Qualified Person authorised to supply certain veterinary medicines and provide advice
• Environmental contamination: Residues from active substances entering the waterways or wider environment (for example, via swimming, bathing, washing bedding, runoff) and potentially affecting non-target species

Purpose of this Call for Evidence

The VMD is seeking evidence to help determine whether point-of-sale advice is necessary for all veterinary medicines containing fipronil or imidacloprid to support responsible use.

As the UK authority responsible for deciding how veterinary medicines can be supplied, the VMD must balance animal health and welfare, public health, environmental protection and continued access to veterinary medicines.  Evidence gathered through this call will help ensure any future decisions are proportionate and evidence based.

Why are we reviewing these medicines?

Recent evidence indicates that these medicines are contributing to environmental contamination, particularly in watercourses.

Monitoring by the Environment Agency in England has found concentrations of fipronil and imidacloprid in surface water frequently exceed toxicity thresholds for insects that live in water.

Research has identified several plausible pathways through which active substances in veterinary medicines used in pets for the treatment and prevention of fleas and ticks, may reach the environment.  These include emissions arising from treated pets or households with treated pets, such as:

• Wastewater from bathing treated pets, laundering bedding, clothing, or materials, as well as handwashing after contact with treated pets
• Direct transfer to surface waters from treated pets entering or swimming in natural bodies of water

Residues have also been detected beyond watercourses, including in wild bird nests.

Veterinary medicines may not be the only source of these active substances in the environment, and relative contributions from different sources remain uncertain.  We are seeking further evidence to improve understanding of these pathways and their significance.

What is under review?

Many veterinary medicines containing fipronil or imidacloprid are currently classified as AVM-GSL, meaning they can be sold without professional advice, for example, in supermarkets.

Given the emerging evidence of environmental contamination, the VMD is reviewing whether this route of supply remains appropriate.  The review will explore whether requiring professional advice at the point of sale could support responsible use and disposal to help reduce environmental risks. 

What evidence are we seeking?

We are seeking evidence, including unpublished data, on:

Environmental contamination

• Residues or effects of fipronil or imidacloprid from veterinary medicines on insects that live in water or other non-target species
• Pathways by which these substances enter the environment
• Monitoring, modelling, or ecological studies relevant to environmental concentrations or risks

Impacts of a potential change in distribution category

We are also seeking information on how restricting the supply routes for these medicines might affect:

• Pet owners
• Animal health and welfare
• Environmental outcomes
• Businesses
• Access to, and availability of, veterinary medicines

This evidence will help ensure our decisions are proportionate, evidence based, and support animals, people, and the environment.

Where prompted, you may upload evidence, such as reports, datasets, publications (maximum file size: 25 MB) or provide a brief citation/link.

Please submit your evidence by 11/06/2026.