Nitrous can help treat depression but it's still not safe 'in the wild'

Since the 18th century, nitrous oxide has been a go-to medical drug for sedation and pain relief. Over the years, many have also inhaled the colourless gas recreationally for a quick rush of euphoria.

Although it's now showing promise as a depression treatment, putting too much nitrous in your body can lead to vitamin B12 deficiencies and neurological harm, says neuropsychopharmacologist Dr Suresh Muthukumaraswamy.

"Something that, in clinical trials, is very safe to do, out in the wild is less safe to do", he tells RNZ's Saturday Morning.

In New Zealand, nitrous oxide, aka nangs, is available in some convenience stores as silver cartridges sold for whipping cream.

In the UK, though, the colourless gas is now an illegal Class C drug and last year, our government also cracked down on its sale and use.

The short-lived high that nitrous oxide delivers to recreational users is not what makes it effective as an antidepressant, Muthukumaraswamy says, but it is a big part of its harm.

"The danger with nitrous is that because the effect doesn't last very long, people want to huff it and puff it all day."

Administered twice weekly in a clinical setting, controlled doses of nitrous oxide can stave off major depression for a number of days, according to a new Oxford University study published in eBioMedicine.

But clinically administered nitrous usually contains 50 percent oxygen, Muthukumaraswamy says, whereas the stuff sold in cream chargers is "pure", and that's not a good thing.

The potential health hazards of huffing this "powerful psychoactive substance", which can include dizziness, seizures and heart issues, are something we need better public education about, he says.

The antidepressant effects of nitrous oxide, which are separate from and longer-lasting than the brief hit of euphoria it can deliver, Muthukumaraswamy says, are similar to ketamine, a powerful anaesthetic also emerging as an effective, rapid-acting clinical treatment for depression, but don't seem as potent.

In the future, it's likely both these drugs and also psychedelic compounds like LSD will be available as treatment options for depression, he says.

A research paper about LSD microdosing, which he has contributed to, will add to our knowledge of that drug's clinical potential when it's published in the next couple of months.

"An occasional (LSD) microdose does not appear to be very harmful to people. We've got plenty of data to support that. Whether it's actually useful to treat some kind of disorder, the data is still coming on that."

In clinical depression treatments using psychoactive substances, people are carefully screened - medically and psychiatrically - and intensively supervised to minimise potential harm from side effects, Muthukumaraswamy says.

But none of that is in place when someone tries to "fix" their own mental health with a substance like nitrous oxide, and things can go really wrong.

"Something that, in clinical trials, is very safe to do, out in the wild is less safe to do."

He recommends anyone considering taking nitrous oxide recreationally or therapeutically first talk to others who've done it before about its effects, and enlist a support person.

Heavy users of nitrous are wise to take extended breaks from the drug, Muthukumaraswamy says, to allow their potentially depleted vitamin B12 levels - which are crucial for ensuring proper nerve and brain function - to reset.

"Maybe get a test to make sure you're not (vitamin B12) deficient."