David Mallon came round from surgery to fix a problem with the blood vessels in his brain, presuming the worst was over.

But while the operation – for a condition called arteriovenous malformation where, from birth, blood vessels form in tangles, increasing the risk of seizures and life-threatening bleeds – saved his life, father-of-four David, 47, is convinced he’s been left with lasting physical damage.

Not from the procedure itself but from the numerous MRI scans he underwent in the days and weeks that followed in 2022.

Two hours after the first scan he felt suddenly ‘drained of energy – and my arms and legs hurt’, says David, a former soldier and mechanical engineer. ‘Every night afterwards I was soaked through in sweat, my arm and leg muscles twitched and my vision was blurred.

‘It’s ruining my life. I still have joint pain, brain fog, memory loss and problems with my vision.’

Having conducted online research, David is convinced he has gadolinium toxicity – a severe reaction to the chemical (gadolinium) that is routinely used in NHS MRI scans to heighten the clarity of images.

Gadolinium in its pure form is a highly toxic, silvery-white heavy metal.

It is administered as a colourless fluid intravenously in up to 50 per cent of those having an MRI scan as it can highlight internal body structures and organs – making it easier for doctors to identify problems on screen.

But it’s toxic – and to make it safe inside the body, the chemical is first wrapped or ‘chelated’ in a binding agent so it can be harmlessly excreted in urine.

However, a decade ago concerns began to emerge that gadolinium may be retained in the body by some people after an MRI scan. There is even a name for this: gadolinium deposition disease.

In 2014, research by Teikyo University in Japan found that in some cases, small amounts of gadolinium were being retained in the kidneys, brain, skin and liver. And a landmark study in 2021, involving patients who reported symptoms of gadolinium deposition disease (including brain fog, fatigue and insomnia) concluded it could have ‘a substantial impact on daily activities’.

There are no figures for the number of cases in the UK – but thousands of adverse effects (1,400 of them labelled ‘serious’) have been reported to the US Food and Drug Administration (its medicines regulator), which now requires gadolinium to carry warnings about the risk of retention in the body.

In the UK, NHS advice for anyone given gadolinium for an MRI is to drink at least one extra litre of water in the hours after a scan, to try to flush the chemical out in urine. It says common adverse effects – impacting around one in ten patients – include a cold sensation in the arm (which had the intravenous infusion), nausea and headache. Less than one in 100 complain of cough, flushing, nasal congestion, light-headedness or hypersensitivity – such as swelling or a rash.

In 2018, the UK’s Medicines and Healthcare Products Regulatory Agency ruled that although research showed ‘low levels of gadolinium’ could accumulate in the brain, there was no evidence it caused neurological harm.

But some experts think the risk should be taken more seriously.

‘I don’t want to see gadolinium agents banned – they are well-tolerated by millions of patients,’ says Professor Brent Wagner, a nephrologist (kidney specialist) specialising in gadolinium toxicity at New Mexico University.

‘But people have the right to know what they are being injected with, and any patient with symptoms of gadolinium deposition disease needs to be listened to and taken seriously.’

Last year, Professor Wagner published research in the journal Magnetic Resonance Imaging that revealed how the toxic chemical might be breaking free of its ‘wrapping’ and leaking into vital tissues and organs.

The study points the finger of blame at oxalate – an organic acid found mostly in plant foods such as spinach, chard, nuts, seeds and soya. Oxalate seems to separate the gadolinium from its protective agent in the body.

Professor Wagner’s work suggests once it escapes, the gadolinium binds with calcium in the body, forming tiny crystals that become embedded on the brain, organs and skin. But why some people react this way and others don’t remains a mystery, he says.

Professor Wagner suggests anyone having the dye before an MRI should avoid drinking fruit juice in the hours before the scan – as oxalic acid (a by-product of oxalate) can form in the body when vitamin C (found in most fruit juices) is consumed.

Such advice comes too late for Catriona Walsh, 50, who had an MRI in 2016 near her home in Belfast to check that her heart wasn’t being affected by hypermobility of the joints, a condition she had from birth. The same connective tissues that make joints too flexible can affect the elasticity and strength of the blood vessels and heart.

The former NHS paediatric consultant, who now works as a nutritionist, was injected with a gadolinium-based contrast agent (GBCA) during the scan to give her images enhanced clarity.

Two hours later, she felt ‘awful’. Catriona recalls: ‘I felt as if my entire body had been electrified. I had chronic fatigue but I couldn’t sleep – I just couldn’t switch my brain off. I was strong – I regularly lifted weights – but suddenly I had no muscle strength.

‘My connective tissue, which is very elastic and loose anyway due to my condition, was worse – I felt my right knee come out of alignment while walking. I had brain fog, my muscles twitched and I had heart palpitations. I felt poisoned.’

Catriona decided to investigate gadolinium as a potential cause of her symptoms – but doctors dismissed her concerns. The only recognised problem with it, she was told, was for kidney failure patients who are unable to flush it out of their systems properly. Over the years, Catriona has met many people via online support groups suffering in the same way.

‘The narrative among radiologists that people given GBCA pass all the gadolinium out is continuing, in spite of it being known that our bodies can retain it,’ she says. ‘There is a reluctance among doctors and radiologists to accept that GBCAs can damage health.’

She managed her own recovery by changing her diet and removing all foods containing oxalate. She also takes magnesium, vitamin D, zinc, copper and B vitamins, which she believes help to combat her symptoms by helping her body’s shift the gadolinium stored in her body.

Most of her symptoms have now subsided. She says: ‘I became acutely depressed after the MRI – I was suicidal for about six months, as are many others – but I am recovered now. I have brain fog sometimes, headaches and occasional visual disturbances.’

Catriona quit her job as an NHS consultant in 2016 after 17 years – and now gives nutritional advice, mostly to those suffering from gadolinium toxicity. She continues to campaign for acceptance within the medical community that gadolinium can damage human health.

However, Dr Giles Roditi, a consultant radiologist for Greater Glasgow and Clyde NHS Trust, believes GBCAs do more good than harm. He says: ‘We know gadolinium can be toxic, but all things can be toxic in high doses – even drinking too much water can be bad for you,’ he says.

‘The chelation binds the gadolinium pretty tightly and millions who have had GBCAs have been helped and diagnosed as a result.

‘For most patients 95 per cent of the contrast agent is peed out in a few hours.’

Dr Roditi believes patients may attribute symptoms of other conditions to gadolinium toxicity.

‘Someone has an MRI because they have arthritis, then afterwards they experience joint pain which they are convinced is caused by the GBCA, not the condition they suffer from.’

Catriona strongly disagrees: ‘Gadolinium doesn’t just take your health, it takes your life as you knew it.’