GPs giving drug used to treat heroin addicts to cancer patients

Irish Cancer Society among those speaking out against ‘unproven’ Low Dose Naltrexone

Irish doctors have been prescribing cancer patients a controversial drug traditionally used in higher doses to combat heroin addiction, the Irish Cancer Society has complained.

Unhappy about the practice, the society has hit out at GPs who treat cancer patients with Low Dose Naltrexone (LDN), saying they are putting vulnerable patients at “tremendous risk” and operating “outside of their scope of practice”.

Dr Robert O'Connor, the society's head of research, said LDN was one of an increasing swathe of drugs being promoted as a "cure-all" in Ireland, despite a lack of scientific evidence it can help treat the disease. He said he was also concerned about anecdotal reports of Irish cancer patients accessing the drug from overseas.

“The evidence indicates that LDN has no benefit in the treatment of any form of human cancer,” Dr O’Connor said. “Clinical trials have been undertaken but there is no evidence from these trials to indicate that the agent has any use in cancer treatment.”


Naltrexone was first approved in the 1980s and is prescribed to people with heroin or alcohol dependencies. Over the past decade, advocates for the off-label use of Naltrexone in lower doses have claimed it can treat hundreds of other serious conditions, including various types of cancer.

But claims about LDN's effectiveness in cancer treatment have been denounced by Irish experts: "There's absolutely no role for Low Dose Naltrexone in cancer treatment outside of clinical trials," said Dr Brian Bird, an oncologist and university lecturer who has led several clinical trials.

“Naltrexone is a very chemically active molecule that we use to reverse opioid toxicity. It may have some anti-fatigue properties but to extrapolate from that that it is going to help treat cancer is dangerous and irresponsible.”

Other experts urged patients firstly to consult the primary medical team treating their disease.


Dublin doctor Edmond O'Flaherty describes himself on his website as "one of the leading pioneers in the use of LDN in Ireland". He runs the Gleneagle Clinic in Blackrock with his son, Dr Andrew O'Flaherty, and recommends LDN as an adjunct to some cancer therapies, claiming it is a "game-changing medication" that is "improving the lives of patients suffering with cancer".

Dr O’Flaherty, a frequent contributor to online forums discussing LDN, said he has prescribed the drug to hundreds of patients, mostly for conditions other than cancer.

He appeared in a 2013 Norwegian documentary about LDN, in which he said he believed many patients would have died had they not being on the drug.

In another interview he was quoted as saying: “Many cancer patients are living much longer than expected, most of them still alive despite metastases in many cases.”

Dr O'Flaherty told The Irish Times: "I have two patients who were expected to die over 10 years ago for lung metastases from breast cancer and from terminal bowel cancer. One of them is still on LDN. The full treatment, of course, including surgery, chemotherapy and radiotherapy, is continued. I have had no breast cancer deaths in the practice for the past 10 years. LDN is used by some but not all of them."

Retired Kilkenny GP Patrick Crowley said he had prescribed LDN to about 240 people – including as an adjunct to treatment for between 30 and 40 cancer patients – since 2005. He said he was "still working with LDN, I'm still registered".

Asked if there was any scientific evidence supporting claims about LDN's benefits , Dr Crowley cited research done by the late American doctor, Bernard Bihari. "There's no big trials done, that's true," he said.

The Merlin Pharmacy in Galway, which supplies LDN only on prescription, advertises LDN on its website, claiming that at doses of between 3mg-10mg a day the drug “exhibits novel and paradoxical effects”.

“Numerous lab and animal studies have been carried out to investigate its novel effects in cancer and autoimmune disorders,” it says. “Further studies are ongoing.”

Brendan Quinn, owner of Quinn's pharmacy in Galway, said there was "huge demand" for LDN, but some of the drug's supporters are over-confident about the drug's potential. "There's a few GPs and consultants who very discreetly prescribe it in pockets in Waterford and Wexford and Cork," he said. "Would I recommend it as a main, or first line treatment, for cancer? Absolutely not."

Adverse reactions

Dr Derek Power, consultant medical oncologist at Mercy University Hospital and Cork University Hospital, said that while LDN was unlikely to cause harm, patients with cancer could be more susceptible to adverse reactions to certain drugs. "Of course there are medical risks," he said. "When a patient is receiving chemotherapy or immunotherapy or any other cocktail of drugs, clinically significant interactions often arise."

Urging scepticism, the Irish Cancer Society’s Dr O’Connor said GPs played a vital role in providing patient care but were not trained to treat differing types of cancer. “Any GP promoting a non-evidence based approach to cancer treatment is therefore putting the health of their patients at tremendous risk and is operating in a field outside of their scope of practice.”

The Irish College of General Practitioners, when asked if it was aware of GPs promoting LDN as a cancer treatment, said it “only supports evidence-based, specialist-led, multidisciplinary care” for cancer patients.

The Medical Council said it gives guidance about professional conduct and ethics to doctors, but not about the use of individual drugs. The Council's guidelines state that any treatment or medication should be "safe, evidence-based and in the patient's best interests".

Cancer researcher Dr David Robert Grimes, a prominent critic of alternative therapies, unproven medicines and fad diets, said Irish regulators needed to do more to combat misleading health advice.

“Instances such as this suggest that regulation to circumvent this is sorely needed to ensure patients receive evidence based interventions, and not untested assertions or outright snake-oil,” he said.

Naltrexone is authorised in Ireland to treat opioid addiction. Low Dose Naltrexone is not authorised, but the Health Products Regulatory Authority said in cases where a doctor wanted to write a script for an unauthorised product, it could be supplied without a license under the direct personal responsibility of the prescriber.