"We ate them at home, and we all found traces and whole pills of prescription medicine. My sister ingested one. I found one in my mouth and spat it out," one said on social media.
"The police are involved. We got off so lucky. Had a child ingested it. There would be more of an issue. I dont know who would do such a thing but its disgusting [sic]!!"
Speaking to the Herald, one of the people who ate the ice creams explained it all started when her sister, while eating her sundae, complained about "an extremely funny taste".
"So we thought, 'OK, better complain to them'. My partner and my sister went to leave when I found one [pill] in mine. We went straight to hospital they said it was someone's medication. But it's not enough to do any damage so suggested keeping going with police."
The hospital said they had no means of checking what kind of medication it was but police are now testing the pills.
Police confirmed they were investigating a complaint, including reviewing CCTV footage provided by McDonald's.
A statement from McDonald's stresses that the investigation has cleared all staff of any wrongdoing.
"When the allegation was made we fully cooperated with the police, including reviewing CCTV footage and carrying out an extensive check of equipment and processes. Food safety is of utmost importance to McDonald's and therefore we treat any complaint seriously."
A McDonald's spokesperson says the company strongly believes the drugs were added to the sundae after it left the restaurant.
"It is disappointing that somebody would make an allegation of this nature, and that the subsequent publicity on news and social media unfairly damaged our reputation, took up a significant amount of time for our people, and resulted in a loss of sales."
