A 21-year-old has suffered a brain haemorrhage after taking two tablets of a legal party pill, leaving his memory and reasoning impaired.

The New Zealand Medical Journal today published the case, the first serious complication from the pills reported in medical literature.

The 21-year-old man, who was unnamed in the article, swallowed two party pills labelled "99.9 per cent-pure DMAA" along with a can of beer and a caffeine tablet.

DMAA, also known as geranamine, has become a popular ingredient in legal party pills after the Government banned BZP in early 2008.

The man took the two pills about 11.30pm, and within 30 minutes he developed a severe headache, said the article written by Christchurch Hospital doctors Paul Gee, Suzanne Jackson and Josie Easton.

The man went home immediately, but when his condition did not improve the next day, he was taken to hospital about 6pm.

He arrived at the emergency department confused and with slurred speech. He was disoriented and could not give a coherent account of what happened, and the right side of his face drooped.

An urgent CT scan showed a large haemorrhage in the left side of his brain.

The man was in hospital for 20 days before being discharged with severe impairments to his memory and abstract reasoning and mild impairments to his speech and right-hand co-ordination.

The authors of the study said the haemorrhage was likely to have been caused by the DMAA and caffeine.

"Despite being sold and used in an inhaler form there is little published research on its [DMAA's] effects in humans and none via the ingested or intravenous route," they said.

MP Jim Anderton, who pushed to ban BZP, said the substitutes that had come on the market were dangerous "chemical rubbish".

He had recently asked the Law Commission for a review on drug laws so party pills would have to be shown to be safe before they could be sold, Mr Anderton said.

"You can't give up on it because if you do, we won't worry about people murdering people because they do it anyway - that's ridiculous," he said.

"It's an incredible situation when a government agency like the Ministry of Health has to pay for the testing of substances made for profit.

"The worst thing of all is young people get sucked in and think they're doing great things."

Massey University senior researcher Chris Wilkins said DMAA had appeared on the market as a replacement for BZP - and both tried to mimic amphetamine and Ecstasy.

BZP had been used by 15 per cent of the population at its peak, but since its ban usage has shrunk to less than 3 per cent.

Its substitutes, led by DMAA, have failed to reach anywhere near BZP's peak level of popularity.

A Ministry of Health report last year said it was aware of four hospitalisations during two months in mid-2008 involving DMAA.

"It is apparent that a potential exists for DMAA to cause some degree of harm when large doses are administered," the report said.

Al Pearson, a distributor for a DMAA-based party pill, said he would welcome a law change that would require sellers to prove the safety of drugs before putting them on the market.

The products he distributed were made in a small Auckland facility, where ingredients were mixed and put in capsules by machines in a clean environment, Mr Pearson said.

The industry had been "destroyed" since the ban on BZP, he said.

"The new products probably don't work as well in effectiveness ...

"We probably do 20 per cent of what we did. It has affected us dramatically."

It was important that users followed the instructions printed on the pills' packaging, he said.

* DMAA replaced BZP in legal party pills.

* It mimics amphetamine and Ecstasy.

* 15 per cent of the population had used BZP at its peak.

* Since its ban usage has shrunk to less than 3 per cent.

* DMAA has failed to reach BZP's level of popularity.