When Did Cannabis Become Illegal in Ireland?

The short answer is 1 April 1937, when the Dangerous Drugs Act 1934 came into force. But that answer is misleading on its own, because nothing much happened on that date. No raids, no seizures, no headlines. Cannabis didn’t become illegal in Ireland so much as it was gradually paperworked out of existence, over roughly fifty years, by a process that started in Geneva and ended with a plant most Irish doctors had simply stopped thinking about.

Here is how it actually happened.

Before the Law: Cannabis as an Ordinary Irish Medicine

To understand the prohibition, you have to understand what was being prohibited.

In 1839, a Limerick-born doctor named William Brooke O’Shaughnessy published research from Calcutta describing the first systematic Western clinical trials of cannabis. His work travelled fast. By 1845, Michael Donovan of the Apothecaries’ Hall in Dublin had published on Indian hemp in the Dublin Journal of Medical Science, with cases contributed by Abraham Colles and Sir Dominic Corrigan — about as establishment as Irish medicine got. Sir Dominic Corrigan published on it in the same year. Fleetwood Churchill followed in 1849.

From the journals it moved into ordinary practice. Cannabis tinctures became a normal dispensary item in Irish and British pharmacies through the second half of the nineteenth century and into the twentieth.

We know this partly from the law itself. When the Irish Free State wrote regulations in 1937, the title of the statutory instrument was the Dangerous Drugs (Medicinal Opium, Tincture of Indian Hemp, Morphine, Cocaine, Etc.) Regulations, 1937. Governments do not write detailed dispensing rules for medicines nobody stocks.

1925: Geneva, and Why Cannabis Was on the Agenda at All

International drug control in the 1920s was about opium. Cannabis was an afterthought — and very nearly not on the agenda at all.

At the Second International Opium Conference, held in Geneva and signed on 19 February 1925, Egypt’s delegate pressed for cannabis to be included, arguing it was at least as harmful as opium. Other delegations supported him. Britain, with an empire full of cannabis-using populations and a Royal Commission on its shelf that had advised against prohibition, objected on procedural grounds. Cannabis went in anyway, under the name “Indian hemp,” defined as the dried flowering or fruiting tops of the female plant.

The Irish Free State was three years old and had a delegate in the room: Michael MacWhite, Ireland’s permanent representative to the League of Nations. His own memorandum of 17 March 1925 describes League members voting against Britain at the opium conference. The newly independent state was present at the moment cannabis entered the international control system, and it was not voting with London.

A note on what we can and can’t confirm: Ireland is often said to have ratified the 1925 Convention in 1931. We were unable to verify that date. British parliamentary records from early 1930 still listed the Irish Free State among signatories whose ratification had not yet been completed, so the timing remains unsettled.

1934–1937: The Act That Didn’t Ban It

The Dangerous Drugs Act 1934 was enacted on 2 February 1934 and commenced on 1 April 1937, under a commencement order made that year. It replaced the British Dangerous Drugs Act 1920 as it had applied in the Free State, and brought Irish law into line with the Geneva obligations.

What it actually did is more specific than most summaries suggest.

Part II controlled raw opium, coca leaves, and “Indian hemp and resins obtained from Indian hemp and all preparations of which such resins form the base.” Import, export and dealing in those were restricted.

Part IV dealt separately with medicinal preparations, including extracts and tinctures of Indian hemp. These were regulated, not banned. Pharmacists could still dispense them, under record-keeping and prescription rules.

So on 1 April 1937, a pharmacist in Cork did not have to destroy anything. They had to keep better records.

This is the part most accounts get wrong. People reach for a dramatic moment of prohibition, and there isn’t one. What there is instead is a slow tightening: international obligations, then domestic regulation, then the gradual disappearance of the medicine from pharmacopoeias and prescribing habits as newer drugs arrived and the regulatory friction grew. By the time anyone thought to ask where cannabis medicine had gone, it had been gone for years.

1977: The Misuse of Drugs Act

The modern framework is the Misuse of Drugs Act 1977, which replaced the 1934 Act and remains the governing legislation today, as amended.

Under it, the detail lives in regulations and orders that can be updated without new primary legislation. The current ones are the Misuse of Drugs Regulations 2017 (S.I. 173/2017) and the Misuse of Drugs (Designation) Order 2017 (S.I. 174/2017).

Schedule 1 of the Designation Order — the most restricted tier, for substances with no recognised medicinal use outside licensed research — lists, among others:

• Cannabis
• Cannabis resin
• Cannabinol, except where contained in cannabis or cannabis resin
• Cannabinol derivatives

A 2021 amendment (S.I. 121/2021) narrowed the cannabinol derivatives entry to exclude dronabinol and its stereoisomers, reflecting the use of synthetic THC in licensed medicines.

Making, supplying or possessing a Schedule 1 substance is lawful in Ireland only under licence from the Minister for Health.

Where the Law Stands Today

Three separate things are often confused. They are governed differently.

Cannabis itself

Still a controlled drug under the 1977 Act and the 2017 regulations. Possession remains an offence.

Medical cannabis

Two routes exist. The Medical Cannabis Access Programme (MCAP) was signed into regulations by Minister for Health Simon Harris on 26 June 2019 as a five-year pilot. It covers three conditions: spasticity associated with multiple sclerosis, intractable nausea and vomiting associated with chemotherapy, and severe treatment-resistant epilepsy. Only consultants can prescribe.

Separately, the Minister for Health can grant individual licences for patients outside those categories. This is the route that Vera Twomey’s long campaign eventually secured for her daughter Ava Barry in November 2017.

Uptake under MCAP has been very low. In a parliamentary reply in March 2026, the Minister confirmed that 74 patients had been approved since the programme began, with applications submitted by just 22 consultants. The Department of Health has since appointed Professor Shane Allwright to chair a review of access to cannabis for medical use.

CBD and hemp

This is where most people get caught out, and the position is genuinely awkward.

According to the Food Safety Authority of Ireland, CBD is not a narcotic and is not a controlled drug in Ireland. However, the FSAI also states that CBD is an unauthorised novel food and therefore cannot legally be placed on the EU market as or in food or food supplements, pending authorisation.

Separately, any part of the cannabis plant is a controlled drug except, once separated from the plant, the mature stalk, fibre from that stalk, and the seed. So hemp seed oil is fine. Oil extracted from controlled parts of the plant is itself a controlled drug, regardless of what it contains.

And on THC: there is no legal threshold or tolerance in Ireland for THC in food, except for hemp seed and hemp-seed-derived products, where an EU limit was adopted in 2023. Foods containing THC at any level are classified as controlled drugs.

Growing hemp

Industrial hemp can be grown in Ireland under licence, with applications processed by the Health Products Regulatory Authority on behalf of the Department of Health, using approved low-THC varieties. Because there is no THC exemption in Irish law, processing the flower domestically is effectively blocked, and licence conditions in recent years have required growers to destroy the flowers at harvest.

So When Did It Become Illegal?

If you want one date, 1 April 1937 is the honest answer: the day the Dangerous Drugs Act 1934 took effect and brought cannabis under control in Irish law.

But the fuller answer is that cannabis in Ireland was never the subject of a single prohibiting moment. It was placed under international control in 1925 by an argument Ireland had no particular stake in, brought into domestic law in 1937 in a form that still permitted medicinal use, and then allowed to fade from medicine over the following decades. The 1977 Act hardened what was already in place.

Ninety years of ordinary Irish medical use ended not with a ban but with a slow accumulation of forms, and almost nobody noticed it happening.

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This is a legal and historical article, and it is not legal advice. The law described here changes, and anyone with a specific question should seek professional advice. Nothing in this article is evidence about any product or its effects.

Frequently Asked Questions

When did cannabis become illegal in Ireland?

The Dangerous Drugs Act 1934 came into force on 1 April 1937, bringing cannabis under control in Irish law. It followed the 1925 Geneva Opium Convention, which first placed cannabis under international control.

Was cannabis ever legal in Ireland?

Yes. Cannabis tinctures were ordinary pharmacy medicines in Ireland from the mid-nineteenth century. Irish doctors including Michael Donovan, Dominic Corrigan and Fleetwood Churchill published on their use from 1845.

Did the 1934 Act ban cannabis medicine outright?

No. It controlled Indian hemp and its resins, while regulating medicinal extracts and tinctures rather than prohibiting them. Medical use faded gradually over the following decades.

What law governs cannabis in Ireland today?

The Misuse of Drugs Act 1977, together with the Misuse of Drugs Regulations 2017 and the Misuse of Drugs (Designation) Order 2017, as amended.

Is CBD legal in Ireland?

CBD is not a controlled drug. However, the Food Safety Authority of Ireland classes it as an unauthorised novel food, meaning it cannot lawfully be sold as or in food or food supplements pending EU authorisation.

Can you get medical cannabis in Ireland?

Through the Medical Cannabis Access Programme, which covers three specified conditions and requires a consultant prescriber, or through an individual ministerial licence. Uptake has been low, with 74 patients approved under MCAP as of March 2026.

Can hemp be grown in Ireland?

Yes, under licence processed by the Health Products Regulatory Authority, using approved low-THC varieties. There is no THC tolerance in Irish law, which restricts what can be done with the harvested crop.