The forced swim test (FST) should not be used on animals in depression and anxiety studies, according to new guidelines from the medicines watchdog.
In these tests, rodents are placed into inescapable containers of water, where they then struggle to escape and stay afloat. Since 1994, 69 articles using the FST have been published by Irish institutes.
Concerns have been raised by welfare organisations and within the scientific and regulatory communities in Europe as to whether this test remains appropriate.
People for the Ethical Treatment of Animals (Peta) has been lobbying for a ban on the use of this test due to the harm it causes to the animals.
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It wrote to the Health Products Regulatory Authority in January calling on it to “take immediate regulatory action to prohibit its use”.
In a response, dated February 26th, Gráinne Power, chief executive of the regulatory authority, said the organisation requested advice from National Committee for the Protection of Animals used for scientific purposes (NCPA) on whether there is a “justified case” for the inclusion of the FST in project applications in Ireland.
The advice was delivered in December 2025 and published on February 6th, 2026, she said.
According to the NCPA advice, FST should not be authorised in projects as a model of depression or to investigate the mechanisms of anxiety or its treatment.
With regard to screening for antidepressant treatments, the NCPA said regulators and sponsors “have a role in reducing the use of FST” but it may be justifiable for this purpose.
“The use of FST for this purpose should be regularly reviewed in the light of current best practice,” the recommendations said.
It also recommended that researchers consult their ethics committee and their designated veterinarian before including this test in a project proposal.
In her letter to Peta, Power said in the studies for which FST is justifiable, “strong justification should be provided as to why it is the most appropriate test”.
“The recommendations as written will make researchers reflect before proposing this as a test in future project applications and it is expected that they will also encourage funding bodies to routinely and robustly challenge the inclusion of the FST in funding applications they receive.”
Peta has welcomed the move, describing it as a “win for the animals”.
Julia Baines, Peta’s head of science policy, said the only thing proven by FST is “that they cause immense suffering to animals and do nothing to improve mental health treatment in humans”.
“Peta applauds the decision to end the use of this pointless and cruel test as a model of depression and in studies of anxiety or its treatment, and will not stop until it’s banned across the board,” she added.
