Megan Fronings didn't order an extra topping on her cheese and mushroom pizza but got one anyway - a maggot.
"I didn't believe it could have been a maggot but it was," she said.
"It was disgusting.
"It made me feel so sick that I had to vomit. It makes me wonder how many other maggots there were," she said.
Miss Fronings, 19, took a picture of the maggot next to the discarded piece of pizza and her friend Sommer-Rose Steer posted the image to the Pizza Hut NZ Facebook page.
"I was with her when she found it and I think it is disgusting.
"It made me feel pretty sick just looking at it. You could tell it was a maggot because of the little black end on it," Miss Steer said.
The photo received more than 320 likes and 140 comments, and resulted in a call from a Pizza Hut representative.
"He offered to replace the pizza, but it would be better if they told us they were investigating and making sure there is nothing else in the store," Miss Fronings said.
The pizza was purchased from Pizza Hut in central New Plymouth but when the Taranaki Daily News called about the incident, the manager declined to comment.
Pizza Hut New Zealand released a statement last night and said they had reimbursed the customer for the cost of the $4.90 pizza.
"Pizza Hut is taking this incident seriously," the statement said.
The company wanted to collect the item in question but Miss Fronings said the maggot had already been washed down the sink.
"If they had contacted us sooner, we would have kept it," she said.
Because of that the company said they were "unable to determine exactly what the customer found in her pizza".
The photo that was posted on Facebook would be used in an investigation.
"We have provided a copy of the photograph to the supplier who provides the ingredients for our pizza toppings for their review and response," Pizza Hut said.
Miss Fronings said she would not eat pizza for a while.
"I don't even want to use the voucher," she said.
"I just want them to make sure it doesn't happen again."