It has become a highly-charged emotional issue, debated in the Dáil and played out on social media with prominent campaigns attracting national headlines.

There is a growing clamour for greater access to medicinal cannabis for patients with debilitating conditions, and in particular children suffering from certain types of epilepsy.

Health Minister Simon Harris has come under intense pressure to make certain cannabis treatments more widely available.

Last November, the Dáil passed a bill tabled by People before Profit TD Gino Kenny to make cannabis available in Ireland for medicinal use, after the Government said it would not oppose the legislation.

Neurologist Colin Doherty

As a result, certain cannabis treatments are likely to be made more widely available under a special access programme.

But many health organisations and medical consultants urge caution when it comes to medicinal cannabis, and warn that there are dangers if the drugs are permitted here without sound scientific evidence.

Dr Brian Sweeney, consultant neurologist at Cork University Hospital, says: "Drugs have to be produced to a standard, with evidence that they work. We cannot just do it based on emotion. It has to be based on science."

Doctors warn that there is a danger of a free-for-all, with patients self-medicating, using unregulated cannabis-based products for a wide variety of illnesses.

In a culture where recreational use is widespread and health advice often received on the basis of anecdote and hearsay, users may even form the belief that they can cure a wide variety of ailments by smoking joints, without regard to the side effects.

"If you get something from a local hemp oil shop or your local drug dealer, you don't know what is in it, and how powerful it is," says Dr Sweeney, who treats patients with multiple sclerosis (MS).

He warns of the particular danger of some synthetic cannabis drugs

"There is a synthetic cannabinoid that has been available in recent years that can have a devastating effect."

He cites a recent medical paper reporting an incident in Brooklyn New York, where a cannabinoid drug was taken and 40 people ended up in an "almost coma-like state".

When analysis of the drug was done, it was found to be 85 times as potent as plant-grown marijuana.

Doctors are coming under pressure to prescribe cannabis-based drugs, such as cannabidiol (CBD), a compound from cannabis which is now being used in medicines.

"What if the drug was found to be harmful?" asks Dr Brian Sweeney. "If a doctor prescribed the drug and a patient died two weeks later, people could turn around and say that the doctor should not have given it.

"We have to follow ethical guidelines. We have to use drugs with proper standards, care, and safety. We have to be aware of the side effects and interactions with other drugs."

Dr Sweeney is not against cannabis-based treatments provided that they have been fully tested, in the same ways as ordinary drugs. As a consultant, he has occasionally prescribed Sativex to MS patients.

Sativex is a drug that contains the cannibanoids tetrahydrocannabinol (THC) and cannabidiol (CBD).

It is recommended for treatment of spasticity that has not responded to other treatments. The drug has been licensed in Ireland since July 2014, but much to the frustration of Dr Sweeney and other neurologists, it is not yet available in Ireland because the HSE and the drug's producers cannot agree a price.Some of Dr Sweeney's Irish patients have picked up Sativex in Spain or in Northern Ireland.

Earlier this year, a government-commissioned report on medicinal cannabis said it could be used to treat some patients for a limited number of conditions.

The report from Health Products Regulatory Authority (HPRA) advised that it could be used for patients with:

• Spasticity associated with multiple sclerosis that is resistant to all standard therapies and interventions whilst under expert medical supervision.
• Intractable nausea and vomiting associated with chemotherapy despite the use of standard regimes whilst under expert medical supervision.
• Severe, treatment-resistant epilepsy that has failed to respond to standard anticonvulsant medications whilst under expert medical supervision.

While the report is likely to lead to certain cannabis-based treatments being made legal, the report's authors do not give an enthusiastic endorsement of the widespread medical use of the drug.

The report says there is only a "moderate benefit for cannabis in a small number of conditions and conflicting evidence, or no evidence at all, in a large number of other medical conditions".

The report says there is insufficient information on the safety of long-term cannabis use for medical treatment.

But the panel of experts who compiled the report signal some of the side effects of recreational use.

These include impaired short-term memory and coordination, psychiatric features of psychosis (including schizophrenia and paranoia), addiction and altered-brain development.

This week, a group of Irish neurologists led by Dr Colin Doherty, announced that it was producing guidelines on safe and beneficial use cannabis-based drugs for treatment of epilepsy.

Dr Doherty said certain cannibanoids showed promise in the treatment of severe epilepsy, but others are inadequately tested or known to be potentially harmful.

"It is our solemn duty to ensure that all treatments are proven to beneficial and safe," said Dr Doherty. "This is particularly important when a new drug is used in a child's developing brain."

The cannabis-based drug Epidiolex is expected to be available later this year on compassionate grounds through a government-access programme.

The drug, which has not yet been fully approved by American and European regulators, was reported in trials to have cut down seizures by 39pc for certain types of severe epilepsy.

Side effects during the Epidiolex trial included sleepiness, diarrhoea and decreased appetite but were mostly mild or moderate, according to the manufacturer's reported results.

Dr Doherty said no other cannabis derivatives or products for epilepsy have been adequately tested as safe and effective, including products with THC (the cannabis compound with potentially harmful psychoactive effects)."

One of the problems for doctors and patients is that cannabis is not like any other drug.

There is a whole sub-culture that clings to it. Side by side with the campaign to legalise medicinal cannabis, is a movement to have it legalised for recreational use.

"One of the problems is that there is still massive confusion and misunderstanding over what medicinal cannabis is," says Peter Murphy, chief executive of Epilepsy Ireland.

"There is a huge distinction that has to be made about what people think of as a medical treatment. Are they talking about a drug that has been fully tested again and again in a clinical trial, and authorised?

"Or are they talking about a potion or a preparation that is not pharmaceutical that may or may not have good quality control behind it?"

He believes much of the misinformation is spread on social media.

"Some people believe that when you are talking about medicinal cannabis, it is the same as taking the drugs recreationally.

"Some people think you can smoke joints to help epilepsy."

It is entirely understandable that patients with some conditions try some of the oils available, particularly when patients are in chronic pain and other drugs have failed.

Hemp oils with only traces of the psychoactive component THC are sold over the counter legally in shops, and ordered online.

But Murphy warns that some people have become attached to the issue of legalising the drugs as a medicine for "non-medical reasons".

"When you see imagery being used of cannabis leaves and terminology you would associate with recreational use, that is doing everybody a disservice - particularly those who may or may not get benefit from medicinal cannabis." Neurologist Dr Sweeney says there should be particular concerns about the use of cannabis among teenagers.

"There is some evidence with THC in particular that you double or treble the risk of psychosis in teenagers at the ages of 14, 15 or 16."

The recent government-commissioned report on medicinal cannabis expresses particular concern about the effects on teenagers.

The report says: "While risk factors have been difficult to determine a consistently emerging theme is that adolescents may be particularly susceptible to the psychiatric and neurocognitive effects."

According to the report, consumption of cannabis during adolescence could disrupt normal brain development.

A special programme to allow patients with specific conditions access to medicinal cannabis is likely to be put in place over the next few months.

In the meantime, patients who wish to use cannabis-based drugs have to apply to Minister Harris for a licence.

Dr Sweeney says the development of drugs can take many years, but the process has to be gone through over a long period.

"It's slow,methodical, and sometimes painful, but you have to go through that period of rigorous research to avoid a repeat of problems in the past with drugs such as Thalidomide."

CASE STUDY

'We moved back from US after the Health Minister gave us a special licence for Tristan's drugs'

Tristan Forde from Dunmanway, Co Cork created history last December when he was legally allowed to use a ­cannabis-based drug in Ireland for a rare form of epilepsy.

Tristan, now aged 3, moved with his mother Yvonne Cahalane and brother Oscar to Colorado in the United States in late 2015 to undergo medical treatment for Dravet syndrome. His dad John stayed behind for work reasons.

On their return after a year in Colorado, Yvonne was given special permission to administer the medication derived from a range of cannabis compounds, after Minister for Health Simon Harris approved a special licence.

She believes the number of cannabis-based drugs that are legally available should be broadened to include the medication that Tristan is currently on.

Tristan is allowed to take the drug under medical supervision after starting the treatment in the US.

At her home in Dunmanway this week, Yvonne says: "Since he started taking it, his life has improved in every way.

"Seeking out a good treatment was a long drawn-out process for the family.

"We began by actually speaking to medical researchers. We aimed high and it took us a long time to get some feedback. And we got first-hand information from parents in the United States.

"We had a very open-eyed opinion on it all. We thought that this could be a good treatment but not necessarily a miracle worker."

Tristan was five months old when he first started getting seizures, and was diagnosed in 2014.

"There was very little effective treatment here. In the first year he was on many different medications, and the seizures were getting worse. Already we felt we were running out of options.

"The seizures he was having were at least 20 minutes long and could last up to an hour - I think sometimes he was in severe pain.

"He had to be treated for pneumonia after food or his milk came back up and got into his lungs. There are a lot of complicated issues with it.

"At one point, there was a huge risk that they would not be able to stop the seizures and he would have to be put in an induced coma.

"We were preparing for the worst and we were almost in mourning to begin with.

"We went over to Colorado in December 2015 because I felt we had no other option.

"The doctor in Colorado wrote us a prescription and we picked it up from a dispensary."

As soon as Tristan started taking the drug, the number of seizures was reduced.

"Since then he has never had drop seizures (where he would suddenly loses muscle tone) and absence seizures (where he blanked out for a time).

"He has not had to be admitted to hospital. Before he had the cannabis drug, he had to be admitted to hospital at least twice a month.

"He was taking nine pharmaceutical medications before. Now he is down to two.

"Now he is also eating for himself, and he is able to sleep much better."

Yvonne urges other families to be cautious when buying some cannabis-based products.

"Some people are being hoodwinked and paying extortionate amounts of money for products that are not really medicine. You also have to be careful of the interactions with other drugs."

CASE STUDY

'I am able to go swimming again since ­using hemp oil'

Former teacher Fionnuala Thornton from Salthill, Co Galway uses CBD oil for her symptoms of multiple sclerosis (MS).

"I have had MS for 30 years, and as a result of it I am in a wheelchair. It took some time before I was diagnosed with it. Early on, some people thought it was all in my head.

"I was doing fine, but then three years ago I developed muscle spasms and it was devastating.

"It consumed my body and it almost locked within itself. It's like a feeling of being wooden.

"My legs were stiff, and it was hard to shower and dress. So, I started looking into hemp oil. It's cannabis oil - the THC that makes you stoned is taken out of it.

"I started taking it in September of last year. I bought it online, it arrives by post, and it has worked fantastically well.

"I have to take 15 drops every day under my tongue using a pipette. It costs me €200 per month.

"It took away the spasms that had locked my body for so long. It enabled me to regain control over my life. I am able to swim now three times a week and I can hold my balance much better.

"My neuropathic pain from damaged nerves is not as bad as it was.

"When I was getting the oil, I checked it out very carefully, and decided to try it.

"It's given me my life back. I haven't felt any side effects."

The MS Society of Ireland advises that all treatments should be undertaken only following consultation with medical professionals.

As the law stands....

Are any cannabis drugs already legal?

Sativex is a whole cannabis extract drug that comes as a peppermint-flavoured mouth spray and it can already be prescribed for symptoms of MS in Ireland. The problem is it isn't distributed here yet. Patients have to get it in Northern Ireland or abroad.

Are there any other plans?

A Government report advised use of cannabis medicine should be allowed under medical supervision for spasticity associated with multiple sclerosis, intractable nausea and vomiting linked with chemotherapy and some severe forms of epilepsy.

Will any specific drugs become legal soon?

Epidiolex is likely to go on the market later this year as its makers seek final approval for treatment of some types of epilepsy. Tests show that it can cut down seizures. The pill consists of almost pure cannabidiol, or CBD, a non-psychoactive compound found in marijuana.

Can you grow your own dope for good health?

No. In some countries, people are licensed to grow cannabis plants to meet their medical needs. Here we are likely to have heavily tested pharmaceutical versions of the drug.

What about those oils in health food shops and other outlets?

Oils containing Cannabidiol CBD are on sale as food supplements in Irish shops. They cannot be sold for medicinal purposes.

They are not allowed to have more than small traces of THC, the psychoactive compound that gets users high.