⚖️ Legal Status at a Glance — Koh Samui, Thailand
Overview
Koh Samui is Thailand's second-largest island and one of its main resort destinations, with an international airport, beach towns such as Chaweng and Lamai, and a large market in private pool villas. After 2022 cannabis shops opened along both main strips, and many are still there. That does not mean buying is legal.
The most important point for visitors: cannabis has been medical-only since 26 June 2025. Without a genuine PT33 prescription, buying and possessing flower is unlawful, and Samui has recently been the scene of shop raids and some of Thailand's largest cannabis-smuggling arrests.
The Law Right Now
A Ministry of Public Health notification under the Protection and Promotion of Thai Traditional Medicine Knowledge Act B.E. 2542 reclassified cannabis flower as a "controlled herb" from 26 June 2025. Legal purchase requires a PT33 prescription from a licensed practitioner. Since September 2025 prescriptions are limited to five approved conditions, and each one is valid for no more than 30 days. Violations of the controlled-herb rules carry up to 1 year in prison and a 20,000 THB fine. Since 1 May 2026, sales are restricted to hospitals, pharmacies, licensed herbal retailers and traditional healers.
Public smoking is banned on every beach, road and pier, prescription or not. Fines go up to 25,000 THB. Edibles, vapes and oils are a separate risk. Cannabis extracts with more than 0.2% THC are still Category 5 narcotics under the Narcotics Code.
On Samui, enforcement has focused on unlicensed shops. On 19 March 2026 immigration police arrested a German man wanted for cocaine trafficking at a cannabis shop in Lamai that had no licence to sell flower. In August 2026 officials shut down a chain, with branches on Koh Samui, Koh Phangan, Phuket and Bangkok, that sold pre-signed ฿300 medical certificates so tourists could buy and smoke on site. The authorities said the scheme broke the law.
Realistic Consequences
A tourist with a gram or two of flower in a villa is not the main target, and small amounts are often dealt with by confiscation and a fine. The risk rises sharply in two situations. The first is moving cannabis off the island. In mid-March 2025, police and customs at Samui International Airport arrested more than a dozen foreigners, most of them British, carrying suitcases of vacuum-sealed cannabis bound mainly for London. On 17 March 2025, two more Britons were stopped at Raja Pier with 165 kg heading for Bangkok. The second is buying from a shop that is being raided: customers without a real prescription can be caught up in the case.
For foreigners, the bigger consequence is often immigration, not the fine. Under the Immigration Act B.E. 2522, drug convictions commonly lead to deportation and a ban on re-entering Thailand. A new Prime Minister's Office deportation regulation took effect in August 2026.
📡 Regulation Pulse
- 26 June 2025: cannabis flower reclassified as a controlled herb; a PT33 prescription is required from September 2025.
- 19 March 2026: a German fugitive is arrested at an unlicensed cannabis shop in Lamai.
- 26 April / 1 May 2026: new ministerial regulations tighten control of THC extracts and restrict where cannabis can be sold.
- August 2026: officials shut down a cannabis chain with a Koh Samui branch that sold ฿300 pre-signed medical certificates.
- 16 August 2026: more than 300 police and officials raid Koh Samui over 60 illegal nominee companies, including villa and hotel businesses; 14 people are arrested.
Public Sentiment
Samui's tourism economy tolerated the cannabis boom, and shop signs in Chaweng and Lamai remain common. The pressure comes from Bangkok: in 2026 national agencies treated unlicensed cannabis shops, nominee companies and foreign-run villa businesses on Samui and Koh Phangan as a single enforcement target.
Practical Advice for Visitors
Do not buy a "medical certificate" at a shop counter. Pre-signed ฿300 certificates were the reason for the August 2026 raids. Only a PT33 issued after a real consultation counts.
Never smoke on Chaweng, Lamai or any other beach. Public smoking is banned for everyone, with fines up to 25,000 THB.
Do not assume a private villa is safe. Possession without a prescription is still unlawful, and a villa does not protect you from a police search.
Carry nothing on the ferries. Boats to Koh Phangan and to Donsak on the mainland leave from piers where police have made cannabis arrests, including Raja Pier.
Do not take cannabis through Samui International Airport. Bags on Samui flights are inspected, and exporting cannabis counts as trafficking.
Treat any drug charge as an immigration problem as well. Deportation and a re-entry ban can follow a conviction. Contact your embassy before signing anything written in Thai.
Related guides: Koh Phangan · Phuket · Krabi · Bangkok
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