KnowYourStuffNZ has identified several high-potency pills in testing this summer season, which are likely to be found around the country over the holiday period.
"These pills should be approached with caution. Users are advised that the only way to guarantee safety is to not take them," the KnowYourStuffNZ website says.
"For those who do choose to take them, our recommendation is to only take a third of a pill at most, and wait at least an hour before considering taking any more."
These pills have been tested to contain MDMA and a variety of fillers.
One type of pill (Pink Mitsubishis) also contained caffeine.
"Combining stimulants such as MDMA and caffeine can increase the risk of heart problems and psychosis. No other psychoactives have been detected in the listed pills.
"A common dose of MDMA is around 80-120 milligrams, depending upon a user's body weight. These pills contain up to three doses in a single pill. We recommend weighing your doses wherever possible.
"Taking too much MDMA can result in a very unpleasant experience, health risks and sometimes even death. If you or someone you know has taken one of these pills and experiences dizziness and vomiting, a sharp rise in body temperature, muscle cramping, heart palpitations, seizures, or unconsciousness, seek medical attention immediately."
The website noted that the MDMA levels were estimates.
Asked for comment, a police spokesperson said there are inherent risks for users of any illicit drugs.
"They contain chemicals in varying doses and strengths, and you put yourself at risk of physical harm by choosing to take these drugs.
Police's advice is simple - the easiest way to prevent harm to yourself is to not take these drugs in the first place."
