Video report by ITV News Meridian's Malcolm Shaw
Campaigners are calling for a boycott of nightclubs as incidents of spiking by injection increase.
Rhian Shillabeer, a student at the University of Kent, is among campaigners organising a boycott of nightclubs on Wednesday, a popular night for students to go out, to raise awareness of the dangers from all forms of spiking.
Rhian has experienced having her drink spiked in the past and said: "Unfortunately I have been spiked, it only happened last month.
"I was with some amazing friends who took care of me and made sure I got home safe and was looked after."
Sussex Police says it is now investigating seven reports of women being injected while on nights out in both Brighton and Eastbourne.
Two initial incidents reportedly took place in the evening on Tuesday (October 19) and in the early hours of Wednesday morning (October 20).
In the following days, four women reported having been injected while out in Brighton city centre.
A woman in Eastbourne has also reported being injected on a night out in the town on Saturday (October 23).
Temporary Superintendent Nicholas Dias, Brighton Police Station
Temporary Superintendent Nicholas Dias, Brighton Police Station said: "It's obviously concerning for us and for the public.
"We want to make sure that everybody is safe when they're out in public, everybody has the right to be safe in the night time economy so that's why we're providing a response and providing effective investigations to try and identity what has happened and who is committing it.
"At this moment in time, the reports that we've had, we've not had any further reports of people becoming a further victim of crime after the incidents themselves."
Hampshire Police is also investigating a similar report in Portsmouth after an 18-year-old woman felt "tenderness and numbness to her arm" while at Pryzm nightclub on Stanhope Road in the early hours of Friday morning (October 22).
Many nightclubs have introduced devices to help prevent drinks being spiked, although it is less clear how to stop spiking by injection.
Some venues are stepping up security and searches on the door.
The Government website Talk to Frank offers guidance on spiking and can be accessed here.
Officers in Sussex are increasing patrols as part of their continued work policing the night-time economy.
Chief Superintendent Justin Burtenshaw, divisional commander for Brighton and Hove, said: "Everybody has the right to enjoy a night out in safety and we fully understand the concerns around these troubling reports, not only in Sussex but across the country.
"We have recently increased the number of officers making targeted, visible patrols around licensed premises such as restaurants, bars and clubs during the week as well as over the weekend.
"Our licensing teams also work with venues to raise awareness around spiking and regularly hold briefings with security staff prior to opening to make sure measures are in place to keep customers safe.
"Unannounced licensing checks throughout the night provide an additional level of support and if you see our officers out and about, please do speak to them – or licensed security staff - about any concerns or suspicious behaviour.
"Alongside our partners we also support a Safe Space in St Paul’s Church on West Street, a location where people who feel vulnerable or distressed can seek support.
"Please be assured that we take all reports incredibly seriously and ask anybody who believes they may have been a victim of spiking to let police or bar staff know as soon as possible so they can be tested before potential drugs leave their system and evidence can be gathered."