The deaths of Reid, Ricky Blackler, Reuben Brown, Krystal Loye, Andre Maddock and William Oliver were also probed as part of the inquest.
All six had epilepsy, a common disorder in which nerve cell activity in the brain is disturbed, causing seizures.
The inquiry found that Reid, who worked as an animal groomer at a pet store, received different brands of antiepileptic medication depending on what pharmacy she visited - some prescribing Logem and some prescribing Lamictal.
But chief coroner Deborah Marshall said "the evidence does not clearly link the brand switch to the seizures that led to the deaths".
The coroner's report states that between 2013 and 2014, Reid suffered almost 10 seizures.
In September 2014, a Hamilton neurologist suggested a combination of lamotrigine and a small dose of Epilim, which Reid's fiancé Alex said worked "wonderfully" and left Reid seizure free for over a year.
According to Alex, on most occasions when Reid's antiepileptic medications were changed, they were well informed. But in 2019, they didn't get any warning about the brand switch.
Reid's mother, Karen, told the inquiry her daughter was on Logem in 2019, but in June was given Lamictal, leading Reid to complain about side effects including headaches and feeling unwell.
The young bride-to-be had her first seizure in two and a half years on July 27, 2019.
An autopsy by forensic pathology registrar Dr Triggs found lamotrigine was confirmed at a level consistent with normal use and declared the cause of death as "Sudden Unexplained Death in Epilepsy".
Dr Triggs also said no injuries or natural diseases could have contributed to or caused her death.
About 70 per cent of people with epilepsy, which affects 1-2 per cent of the population, are able to control it well with medication.
Reid also stopped taking Epilim, another antiepileptic medication, about 12 months before her death.
Neurologist Dr Elizabeth Walker told the inquest the likely cause of Reid's fatal seizure was withdrawal from Epilim.
