Three women who claimed they were spiked with a needle had no drugs in their systems, police have revealed in a bid to give "peace of mind" to clubbers.
Devon and Cornwall Police received four reports from women who were partying in bars and nightclubs in Exeter between Tuesday and Wednesday this week.
All four said they felt unwell during the night out and feared they had been "targeted in assaults using needles or through having their drinks spiked".
After carrying out a series of toxicology tests on the alleged victims, the force found three of them tested negative for containing anything in their system that would "suggest drink-spiking or having been drugged in another manner".
The fourth victim was "outside the forensic window" with a blood sample taken for further testing.
No further action is being taken in the case of the three women who tested negative, the force said.
However, officers confirmed they are continuing to investigate the fifth case of a woman who was assaulted with a needle in Fever & Boutique nightclub last Saturday.
The nightclub has been approached for comment.
'We hope that these clear tests will give peace of mind'
A spokesman for Devon and Cornwall Police said: "We continue to encourage those who feel unwell to raise this with door or bar staff at the earliest opportunity.
"We hope that these clear tests will give peace of mind to these four women that they were not victims of spiking, and feel reassured by the swift and thorough response from bar staff, police and medical professionals."
Student unions, campaigners and ministers have condemned the reported surge in cases across the nation with dozens of women claiming to have been targeted.
Police have said there have been around 140 confirmed reports across September and October of drink spiking and 24 reports of some form of injection.
National Police Chiefs' Council lead for drugs, deputy chief constable Jason Harwin, commented: "There are both male and female victims, though the majority have been young women. Alleged offences have taken place at licensed premises and private parties."
Dominic Raab, the Justice Secretary, has described the alleged assaults as "despicable" and promised attackers would face the "full force of the law".
In the wake of reported attacks, campaigners are planning to boycott bars and clubs nationwide until further safety measures have been introduced in venues to tackle spiking.
A Girls Night In, the campaign group organising the movement, intends to boycott clubs in over a dozen cities - including Nottingham, Durham, Bristol, Brighton and Edinburgh - within the next few weeks.
A petition calling for mandatory searches in nightclubs has also received over 160,000 signatures in recent days.
'These two arrests come after a plea for people to come forward'
Nottinghamshire Police said they have received 15 reports of young men and women being spiked with "something sharp" since October 2.
This has prompted at least five bars across Nottingham to give women the night off in solidarity with the city's upcoming boycott next week.
Officers arrested two men, aged 18 and 19, on Thursday as part of an ongoing investigation into spiking.
Kathryn Craner, superintendent of Nottinghamshire Police, said: "These two arrests come after a plea from myself and the force for people to come forward and report any incidents to us.
"We have now arrested two men this morning, October 22, on suspicion of conspiracy to administer poison and both are still in custody as our enquiries continue.
"I would like to reiterate that these arrests have not been made in connection with a specific case or incident reported to us over the last few weeks of both drink spiking and spiking by a needle."
It comes after a 20-year-old man was arrested after one woman reported "a scratching sensation" and suspected her drink had been spiked at a club in Nottingham city centre on September 11.
Elsewhere, a 35-year-old man was arrested on Thursday night on suspicion of possession of drugs with intent to administer them at a Lincoln nightclub.