People who overdose on the recreational drug GHB are sometimes incredibly ungrateful when their lives are saved, an emergency doctor says.

Seven people within 48 hours had to be treated in Auckland for overdosing on GHB and Waikato Hospital's Emergency Department Clinical Director Dr John Bonning has heard cases of patients recovering, ripping off ventilation masks, and storming out.

LISTEN TO DR BONNING DISCUSS GHB AND ITS EFFECTS ABOVE 

Dr Bonning says a lot of resource has to go into treating comatose GHB patients - including attaching a mask to help them breathe.

"These people just yank their masks offs and storm out of the emergency department because they don't want to be there anymore," he said.

"If you take only two times the recommended dose, it will cause quite profound respiratory depression, depression in neurological function, and coma."