Party drug "poppers" should not be banned in the Government's crackdown on so-called "legal highs", according to MPs.
The call came in a report by the Commons Home Affairs Select Committee on the forthcoming Psychoactive Substances Bill.
It also accused ministers of rushing through the new law, resulting in a number of "weaknesses" and concerns from experts, lawyers and police.
The legislation, which is going through Parliament, will introduce a blanket ban on the production, distribution, sale and supply of so-called designer drugs - officially known as new psychoactive substances (NPSs) - after they were linked to scores of deaths.
Sellers will face up to seven years in prison.
Poppers, the name given to a group of chemicals called alkyl nitrites, are normally sniffed from a bottle producing a short head-rush. The Home Office has said they will be covered by the new laws.
The committee referred to the conclusion of the Advisory Council on the Misuse of Drugs (ACMD) that the misuse of poppers was "not seen to be capable of having harmful effects sufficient to constitute a societal problem".
The report said: "Therefore we recommend they should not be banned. If in the future there is any evidence produced to the contrary, then 'poppers' should be removed from the exempted list or controlled under the Misuse of Drugs Act."
The committee also concluded that:
:: There should have been an impact assessment of the existing ban of NPSs in Ireland before the bill was published.
:: Nitrous oxide - known as "laughing gas" - should be reviewed by the ACMD to consider whether it should be controlled under the existing laws for illegal drugs given the growth in its use and "the associated social harms".
:: The definition of a psychoactive substance should be reconsidered following questions over whether that the government can be confident that substances which are beneficial will not be criminalised and suggestions from Police Scotland it "might be problematic in ensuring a successful conviction".
:: There is a lack of clarity in the bill on the relative harm associated with different types of NPSs and the appropriate sentences and guidelines should be requested from the Sentencing Council.
Keith Vaz, chairman of the committee, said: "Britain uses more psychoactive substances than any other country in Europe and is at risk of being overwhelmed by the sheer scale of this problem.
"Legislating on this issue is the right thing to do, however doing so at speed without any consultation may be counterproductive.
"The concerns expressed have been dealt with in a piecemeal manner and there has been unsatisfactory communication with the Advisory Council, the very body that the Ministers should rely on for advice."
He said every effort must be made to ensure the sale of NPSs does not move from high street head shops to the internet, adding: "A young person dying as a result of using these substances on a night out is every parent's worst nightmare.
"We are dealing with unscrupulous people, often involved in activities thousands of miles away, who care nothing about damaging health and lives and even causing death in the pursuit of profit."
The committee also said the term "legal highs" is "misleading and inappropriate" as it "sends out a message to young people that these substances are both 'legal' and will have a 'desirable' effect".
More than 500 new drugs have been banned but the current system is seen as laborious as substances have to be assessed individually before they can be outlawed and manufacturers often produce new versions almost immediately after a previous form has been prohibited.
The Home Office said the Government is continuing to consult with the ACMD on the bill.
Policing minister Mike Penning said it will "fundamentally change the way we tackle new psychoactive substances" and "put an end to the game of cat and mouse in which new drugs appear on the market more quickly than Government can identify and ban them".
He added: "The blanket ban will be on the production, supply and importation of these harmful substances, which caused the unnecessary and tragic deaths of 129 people in the UK last year.
"Unscrupulous suppliers will not be able to hide online, as our bill will give police the power to shut down websites trading in these potentially dangerous drugs."