Maria (not her real name) watched her toddler son scamper away from her as she sat helpless in a wheelchair and all she could do was pray to God for help. With an older disabled child, her husband working long hours and with her just being diagnosed with possible MS, life was becoming impossible.

"I'd just been told the results from the MRI had shown lesions on the brain which probably meant MS. I was struggling to walk, so as I sat in a hospital corridor waiting for a doctor, Sean, my toddler, ran off and I realised I couldn't run after him. Life was difficult with a disabled child and a toddler but I realised it was about to become harder. All I could do was pray."

Her prayers were answered, it seems, the next day in the form of a book aptly called Up the Creek with a Paddle, by Mary Bradley. It told the story of Mary's husband who was also diagnosed with MS but found help in the form of Low Dose Naltrexone (LDN).

The drug is already approved by the FDA in higher doses for treating heroin addiction. It affects the receptors in the brain, dulling cravings.

According to Dr Gabriel Stewart, a Dublin GP, Naltrexone in the low dose form, 4.5mg, works completely differently. "MS suffers are immune compromised. What LDN does is boost endorphin production, which, in turn, enhances immunity. I have treated many patients in this way and when used in conjunction with diet, I have seen excellent results."

Despite the results, many GPs will not prescribe LDN for patients with auto-immune diseases. Dr Stewart says this is because there have been no official clinical trials and doctors are concerned that there maybe litigious repercussions.

"There are over 100 drugs prescribed off-label. This is where a drug is used for one illness and is then found effective in another illness. That's not unusual but without a published trial, doctors are reluctant to prescribe it."

Multiple Sclerosis Ireland says: "Anecdotal information suggests LDN may be useful in treating MS but until conclusive evidence is released by the scientific community, we remain optimistic about its future benefit for people with MS."

The UK's MS Society agrees. They say that there are many anecdotal claims to suggest that LDN is an effective treatment for MS but there is currently not enough medical evidence to prove it.

Paul Gannon was diagnosed with MS in 2005. His doctor wanted him to start a strong MS treatment called Rebiff, but Paul had done some research on LDN in MS treatment and asked to be prescribed that instead.

"My neurologist flatly refused to prescribe it for me. He said there hadn't been adequate trials on it, even though he knew it had been used in other treatments for years.

"He basically told me it was either conventional MS drugs or find another neurologist. In the end he prescribed me Copaxone, a different MS drug that you can take with LDN and I get my LDN prescription from a different doctor."

When he was first diagnosed, Paul was suffering from fatigue, pins and needles, pain, nausea, memory loss and what he says was the worst aspect -- bladder urgency. "I had to run to the loo constantly," he says.

"I was very scared because with two small children and another on the way as well as my own construction company to run, I wondered how I would cope. Could I support my family, would I be able to play with my kids and what would happen to the business?"

Within days of taking LDN, the worst of his symptoms improved. After a recent hospital check up, the doctor said that if it wasn't for the diagnosis he had in front of him, he wouldn't believe Paul had MS, such was the improvement in his reflexes and overall health.

Because LDN improves the body's immunity, it can be used in the treatment of other autoimmune diseases such as HIV, Parkinson's, cancer and Crohns disease. This is according to Dr Bernard Behari, a New York physician who has been prescribing LDN since 1985.

It was through this doctor that Mary Bradley who wrote the book, Up the Creek with a Paddle first heard about LDN. By that time, her husband Noel had no feeling in his legs and had great difficulty getting around.

"Noel was diagnosed in 1998. By the time he started on LDN, he needed a cane to walk around, suffered from fatigue and couldn't stand or walk for very long. Within two weeks of taking LDN, his condition stabilised and improved slightly. But most importantly, there has been no progression since taking LDN in 2002.

"LDN is not a cure, there is no cure for MS. All conventional drugs can do is halt the progression for some people and nothing for the rest. Anecdotal evidence shows LDN can halt progression in most people and many can regain a little of what they've lost to the disease.

"I realise that I don't know the whole LDN story or have all the answers. Without a clinical trial, nobody does."

There have been no double blind clinical studies done on LDN because it is already FDA approved and cheap so there is no monetary incentive to drug companies for doing one.

However Brendan Quinn of Quinn's pharmacy in Galway has managed to get the Western Health Board to cover LDN and has helped many people get it. Other campaigners have set up a web petition in order to pressurise the government into beginning a trial and to date it has over 9,500 signatures.

One GP who specialises in fertility said: "LDN helps but it must be used in conjunction with diet. Mineral supplements and dietary treatments are very important. LDN on its own wouldn't be enough. And there are side effects such as vivid dreams, sleep disturbances, alcohol intolerance making hangovers worse, although generally they disappear."

The doctor, who wishes to remain anonymous, added: "People with MS are already immune compromised, the drugs suppress an already immune compromised patient and that can damage their overall health."

Mary is emphatic: "It is not a question as to whether or not LDN works, it is a question as to how well it works."

But whether LDN is the new wonder drug of the 21st century or not, without a widely published clinical trial it may remain the best wonder drug we never had.

- Sarah Spendiff