Video report by ITV News Correspondent Geraint Vincent
Hannah Green and her boyfriend, Court Amys, arrived at the H10 Costa Adeje Palace on Saturday with their one-year-old son.
Authorities confirmed on Thursday that two other confined guests in the hotel have also been infected.
Speaking to ITV News, Ms Green and Mr Amys said they were "really worried" and running out of supplies for their baby son.
Ms Green, from Hertfordshire, said she was already going "stir crazy" after two days stuck in their room in the four-star H10 Costa Adeje Palace.
The 27-year-old says said feels "upset", "panicked" and concerned for her son as she has no information about how children are affected by the coronavirus.
She told ITV News: "It's just hard not knowing what's going on or how long we're going to be here for".
Ms Green described the ordeal as the "holiday from hell".
Mr Amys said he was the only one in the family to have left the room, he said the couple would not be taking their son out of the room "until we've got the all clear".
Speaking to ITV News, Mr Amys said: "We're soon going to run out of nappies and wipes and things and we're hoping that we're going to get supplied with that sort of thing".
He added: "We don't know anything. The hotel have told us nothing at all apart from stay in your rooms".
Mr Amys said some people were walking around the hotel "with masks on and gloves on, and added the resort were serving a buffet lunch on Wednesday.
The couple said they would not be attending for fear of the spread of the virus. Mr Amys said he was "confused" by the decision to serve lunch.
British holidaymakers Elaine Whitewick, a hairdresser from East Keswick in Yorkshire, and her friend Jayney Brown are also on lockdown in the resort.
They told ITV News they had been "shocked" to receive the note pushed through their door on Tuesday morning saying the hotel was being shut down for health reasons.
Ms Whitewick said they were running low on water and food supplies too.
A statement from the hotel said: "Following the report of a possible coronavirus case detected in a customer from Italy, staying at the H10 Costa Adeje Palace, H10 Hotels has implemented all health and operational recommendations from the health authorities to ensure the safety and wellbeing of customers and employees.
"Additionally, we are providing customers and hotel staff all the necessary care and attention so that, despite the inconveniences this situation may cause, they are taken care of in the best way possible."
Some 1,000 guests have been prevented from leaving the complex.