In the early hours of Saturday morning, The Alfred was inundated with patients, some shaking, hallucinating or suffering from psychotic episodes.

All of them had one thing in common: on Friday night they had been out partying at the same venue, and had ingested the same toxic drug.

A deadly batch of ecstasy has been blamed, with three deaths and about 20 people requiring hospital treatment, including a 17-year-old boy who remains in a serious condition at a Melbourne hospital.

Emergency and trauma physician Dr Peter Cameron said that between 2am and 10am on Saturday at least 12 patients arrived after having been at the same Chapel Street nightclub.

"Each weekend we do get some drug-affected people; it's normal to get five to 10 each day, for various reasons," Dr Cameron said.

"On this particular weekend, there was clearly a group of people, we think 12 but it's difficult to know ... who had just taken one pill, and they presented with varying degrees of unwellness.

"They seemed to have all been clustered around one venue."

"The majority presented because they were frightened and felt as if they might die. A couple were quite serious. One was out of control, another violent and another unconscious," he said.

"Some of them were very anxious. They felt like they were going to die, pupils were dilated, they had a very fast heart rate and were shaky, a bit like if someone was about to attack them with an axe.

"Some of them were hallucinating, and there were one or two serious ones where they were violent and uncontrollable. Some didn't reach the hospital and died at the scene.

"When they're violent, we might have to give them a shot of ketamine to bring them down."

Dr Cameron said some of the patients were "novice" drug takers and others more experienced.

"My understanding is that the drugs were quite cheap, and so it's probably cheaper to get the drug than a glass of beer, which probably exacerbates the situation with young partygoers," he said.

"It's hard for the police. We rang them and said this is a bit crazy; they said we're onto it.

"It's the worst I've seen for a while, but you have cycles where you'll have 10 or 20 people come in over a few days because there's a new batch or a new dealer or something. That's the nature of it."

The incident has spurred further discussion around the need for safe pill testing at festivals and venues, but Dr Cameron said testing the drugs still didn't make them safe to consume.

"They're all unsafe batches. There's no such thing as a safe batch of a street drug, because there's no quality control," he said. "The testing is dodgy, because you could test one tablet and the next tablet is different.

"I strongly disagree that the answer to this is to have tablet testing. The answer is not to take the tablet. The idea that you can test a few tablets and say it's OK is farcical."