On Saturday night, two very different worlds collided when Taylor Swift fans met a rave.

If you’re going to take drugs at a festival, look after your friends and know the risks.

Sydney mother-of-four Mel Gabbusch says she was shocked by the behaviour of a group of revellers at Stereosonic who didn’t seem to understand just how serious drug overdoses could be.

Taylor Swift’s only Sydney concert and dance music festival Stereosonic were both on at Olympic Park on Saturday night, with the two crowds crossing over on public transport and in common areas.

Gabbusch, 34, was enjoying dinner with a friend before Swift’s concert when she noticed a seriously drug-affected woman nearby.

“I saw some girls walking around near the restaurant. One was walking really unsteadily on her feet, they sat down at a table and she had fallen in her seat and was slumped there,” Gabbusch told Mamamia.

She realised the woman had passed out.

“She looked really bad so I kept watching and they weren’t doing anything. I went over and I asked her friends: ‘What’s she taken?’ and they said they didn’t know.

“I said ‘Come on, what’s she taken? This is serious’ and they eventually said MDMA.”

Gabbusch said she was shocked at their lack of action, and described the women as being unsure that their friend needed medical attention.

“I told them they needed to call an ambulance, but they asked me ‘can you do it?’, and so I called the ambulance and then I lay her on the ground, checked her airways, just whatever the Triple-0 person was saying.

“While we were waiting her friends were talking about missing Stereosonic, and I just turned around and said to them ‘you should be more worried about your friend’,” she said.

After the ambulance arrived, Gabbusch left the group, and went back to her friend. She then snapped a picture of the scene, intending to share it with her teenage son.

“Their behaviour was quite annoying and quite scary,” she said.

“There were so many families coming from the train… kids everywhere and my issue was, and this is why I took the picture, was that I wanted people to know how serious drugs are and I wanted to show my son.”

Gabbusch shared the picture on Facebook, because she wanted her 15-year-old son to share the story with his friends.

She has since taken it down, because she said people were criticising her for taking the picture.

There were 69 arrests at Stereosonic, and one woman died from a drug overdose.

Doctors are calling for pill testing to be made available to festival-goers, to help prevent further drug deaths.