A Conservative former minister has "outed" himself as a poppers user, as sweeping new powers banning the substance cleared the Commons.
Crispin Blunt warned he and many gay men were "astonished" by the Government's plan, adding respect for the law would "fly out the window" because of the ban.
Home Office Minister Mike Penning told the Commons he has offered a "compromise" which will mean poppers are banned but a review will be undertaken to see if it should be overturned.
A final decision taken by Home Secretary Theresa May and Health Secretary Jeremy Hunt will be made before the summer, Mr Penning said, before the Psychoactive Substances Bill received an unopposed third reading.
The Bill creates powers to make all psychoactive substances illegal with listed exceptions instead of forcing each new legal high to be individually banned as they are created and sold.
It bars the production, distribution, sale and supply of legal highs - imposing a maximum seven-year prison term on convicted offenders.
A Labour-led amendment to exempt poppers from the banned list was defeated by 309 votes to 228, a majority of 81 during report stage in the Commons.
Peers will have to examine amendments made by MPs before the Bill can become law.
Speaking in the Commons, former justice minister Mr Blunt said: "There are some times when something is proposed which becomes personal to you and you realise the Government is about to do something fantastically stupid and I think in those circumstances one has a duty to speak up.
"I use poppers, I out myself as a popper user, and would be directly affected by this legislation and I'm astonished to find that it's proposing to be banned and, frankly, so were many other gay men.
"If I follow my own mindset reaction to this it simply serves to bring the whole law into disrepute.
"Choosing to ban this, which I have been using and I know has been used ... for decades, then respect for the law is going to fly out the window for people if that's the drug that they use."
He noted warnings indicate there will be increased use of class A and B drugs plus increased transmission of sexually transmitted infections.
After the vote, Mr Blunt told BBC Radio 4's PM programme: "Frankly I don't think most MPs will have known the detail of this legislation. They trust their colleagues on either side who do take a keen interest, either a leading interest or get themselves involved in issues ... "
Pressed on whether he would keep using poppers, Mr Blunt said: "I have to obey the law. Personal possession is not going to be made a crime under the law, the issue of supply will be made a crime.
"I imagine now that gay men who use these things will be stocking up ... and then they will be able to be legally supplied again."
Conservative David Davis, a former shadow home secretary, said in the Commons: "I understand it's intended not to victimise current users of this drug but it does put them in a position where they might be susceptible to blackmail if they are a public figure dealing with a criminal.
"So it does seem to me that it will criminalise people who it does not intend to criminalise."
Shadow home office minister Lyn Brown said she was afraid that banning the products would "push their use underground and away from regulatory controls that currently exist".
Keith Vaz, Labour chairman of the Home Affairs Select Committee, added: "To ban then un-ban sends a powerful message out to a section of our community that they are not being listened to and to experts who have given evidence to us that they are wrong."
Tory Mike Freer (Finchley and Golders Green) said poppers help LGBT couples achieve intimacy that would be more difficult without the drug's muscle-relaxing properties.
Mr Freer said it therefore has an important emotional and mental health benefit, although he backed the ban.
During the third reading, Mr Penning said of the Bill: "I think it will save lives. As a father I can only imagine what others have gone through that have had their loved ones taken away from them or badly damaged.
"I also panicked like hell when my daughters went to university. They're really sensible kids, they understood everything but they also could easily have been dragged into the situation that 'this is safe'.
"It wasn't safe and we've made sure that everybody knows that now."