Police confirmed to the Herald they are investigating the incident.

"Police have received a complaint relating to an incident where two people claimed that there were pills in their ice creams that were purchased from a fast food restaurant in West Auckland yesterday evening," Detective Senior Sergeant Roger Small, Waitakere Police, said.

"The individuals took themselves to hospital to be assessed. 

"We are looking into the incident and making enquiries to establish the nature of the pills."

Contacted by the Herald, McDonald's says it is cooperating with police.

"Police have notified us of a claim that a customer found a foreign object in McDonald's product. We are cooperating with the police investigation, including stripping the shake and sundae machine and sauce dispensers to illustrate how they work," a spokesperson said.

"We've also reviewed CCTV and provided this to police. Normal procedures were followed and there was nothing untoward in the filling and operation of equipment, or as the order was made and handed to the customer in drive-thru. We are trying to contact the customer so we can confirm more details."