Two men aged in their late 20s who apparently overdosed on a ketamine derivative at the University of Canberra on Thursday morning were found unconscious by students and were taken to Calvary Hospital in a critical condition.

ACT Policing said the young men thought they were taking party drug ecstasy, warning there was a ''bad batch'' of drugs on the market in Canberra, circulating particularly in nightclubs. On Friday morning the hospital confirmed the two men were recovering well.

The woman, speaking on the condition she would not be named, told The Canberra Times she took a capsule containing a flour-like substance on Saturday night.

She, too, thought the drug was ecstasy and she had been planning to spend a night in with friends, but within about 90 minutes she was unconscious.

Her friends were unable to get any response from her for about four hours and when she eventually came round she initially had no recollection of most of the night, but when her memories began to return she recalled being paralysed and unable to respond to her friends' questions.

On Sunday morning she felt unco-ordinated and was unable to walk properly or hold a coffee cup. She would forget what she was saying mid-sentence and forget what she was doing mid-task, and it was not until Tuesday that she felt back to normal.

The woman said an older male friend also had a bad reaction to the drug, vomiting and feeling unwell the next day.