A mum has urged people to stop getting high on 'laughing gas' after it left her son with lifelong damage.
Bristol mum-of-two Helen Brown says her son's partying days are over at the age of just 20, after he suffered brain and nerve damage following frequent inhalation of nitrous oxide.
The psychoactive drug is also known as NOS and is encased in the tiny silver canisters often seen littered around streets and parks.
Helen, who did not want her son to be named, said he has been told by doctors that even drinking alcohol could exacerbate his condition and potentially lead to paralysis.
She told Bristol Live: "People need to know that every time they take it, they are rolling a dice with their future.
"I've done a little bit of research and there are people who have ended up in wheelchairs for life.
"The mindset he had was that nothing was going to happen to him - his party days are over now."
The 47-year-old shared a Facebook post last week to raise awareness of the dangers, which has since been shared more than 2,000 times.
She described NOS as "vile", writing: "Please, please, please educate your young people about the devastating effects of these things
"For a five minute buzz my son now has a lifetime of uncertainty and pain."
She said he had suffered severe B12 deficiency and permanent brain damage, and there are now uncertainties about the longer-term implications.
The drug is illegal for human consumption and can cause a feeling of euphoria, fits of giggles and hallucinations.
Despite many users considering it to be harmless compared to harder drugs, there is growing evidence that it can have damaging and potentially long-term effects.
However, there are legal uses of nitrous oxide that make it easily available to buy.
It is often used for numbing pain during medical procedures, and for filling up catering aerosol cans like for whipped cream.
Inhaling too much can result in people falling unconscious and suffocating from the lack of oxygen, which has had fatal effects in the past.
However, Helen said the effect on her son was much more gradual.
'He had pins and needles and cramps'
The care assistant, who lives in Lawrence Weston, said: "It wasn't like he collapsed there and then.
"It was a long-term thing, he was feeling unwell and really lethargic and fatigued all the time, and suffering from severe cramps and pins and needles in his hands.
"Eventually he started collapsing - his legs started giving out."
She said he admitted to inhaling the drug from balloons at parties, which she had developed suspicions about after finding balloons his pockets while doing the washing.
He started to develop pains around January and February and went to the GP, who carried out blood tests.
Helen added: "He said he'd got a severe B12 deficiency caused by the inhalation of nitrous oxide.
"They sent him for brain scans and found he has damaged the nerves in parts of his brain and spine. He was told it was likely caused by inhalation of nitrous oxide
"He still has to go for some more tests but they've told him even the consumption of alcohol will exacerbate his condition."
She said she was "shocked" as she was not aware before how serious the consequences of NOS can be.
Helen added: "He can walk and still function fairly normally, but he is still in pain and there is uncertainty about the long-term effects.
"We don't know when his legs are going to give out, the next minute he's on the floor."
The mum has concerns about how widespread the use of NOS is in Bristol and how readily available they are.
'I see mountains of these canisters'
She said: "These canisters are everywhere, mountains of them.
"If there were the amount of syringes than there are these canisters, there would be uproar.
"It's so easy to get hold of them."
She also raised concerns about their impact on the environment, as well as on the council's street cleaners who have to tidy them up.
The psychoactive drug is covered by the 2016 Psychoactive Substances Act, and it is illegal to give it away or sell it for human consumption.
Although there is no penalty for possession, supply and production is an offence that carries a sentence of up to seven years in prison, or an unlimited fine.
Helen's son is now on an intensive course of B12 treatment with three injections per week.
She said she has been "overwhelmed" by the response on Facebook.
She added: "I wanted to get it out there to these young ones that this is having long-term effects.
"My son has warned his friends, and he has even said he would be happy to go into schools to talk to kids about the long-term damage.
"Fingers crossed we can get something positive out of this."
More information about the risks of nitrous oxide are available via Talk to Frank.
What the experts say
The guidance on the website states: "Heavy regular use of nitrous oxide can lead to a deficiency of vitamin B12 and to a form of anaemia.
"Severe B12 deficiency can lead to serious nerve damage, causing tingling and numbness in the fingers and toes.
"This can be very painful and make walking difficult.
"Regular use can stop you forming white blood cells properly."
In October the chief medical officer of Wales Dr Frank Atherton also shared a warning about nitrous oxide, telling the BBC it can cause irreversible paralysis.
