Reference
Substances
This is not a drug-tourism guide. It is a risk reference for the substances that intersect with adult-travel safety and scam risk across the Asian countries this site covers, in four categories: alcohol and drink-spiking; recreational drugs with severe legal exposure; counterfeit and adulterated supply; and prescription-medication considerations. The legal consequences described are drawn from primary statutory sources.
Legal severity summary
Singapore, Malaysia, and Indonesia impose the death penalty for drug trafficking at defined quantity thresholds. These are not theoretical penalties: all three countries have executed foreign nationals. The phrase "possession" in these jurisdictions means possession of any amount; the phrase "trafficking" is defined by weight thresholds, not by evidence of intent to sell. Carrying drugs for personal use above a defined threshold is legally indistinguishable from trafficking in these jurisdictions.
Alcohol and drink-spiking
Alcohol intersects with adult-travel risk primarily through two mechanisms: impaired judgment that allows other scam or safety patterns to operate; and deliberate drink-spiking with sedative compounds. The two are distinct risks with different prevention strategies.
Drink-spiking with sedatives — most commonly with benzodiazepine compounds (rohypnol equivalents, clonazepam, midazolam), ketamine, or GHB — is documented in nightlife contexts in Bali (Kuta and Seminyak), Bangkok (Nana Plaza, Sukhumvit side streets), Manila (Ermita area), and to a lesser extent in Phuket. The mechanism is consistent: a drink is placed in front of the target, either by a new acquaintance, a bar worker, or left while the target's attention is diverted. Sedation occurs within 20–30 minutes; the target either becomes compliant (allowing card theft and ATM use) or loses consciousness and is robbed. GHB at high doses combined with alcohol can cause respiratory depression — this is the life-threatening variant.
Standard precautions: never leave a drink unattended; do not accept a drink poured or carried by someone you did not watch prepare it; the moment a drink tastes different from what you ordered (unusually sweet, bitter, or chemically tasting), do not continue drinking it; tell someone where you are (hotel front desk, travelling companion) before going to nightlife areas alone.
Impaired judgment is the simpler and more common risk: the bar-fine padding, KTV bill doubling, and fake-police shakedown scams described on the scams page all operate significantly more effectively against people who are intoxicated. Setting a per-session alcohol budget before entering a venue — and sticking to it — is a more reliable protection against these patterns than any in-the-moment judgment.
Methanol poisoning
Methanol-contaminated alcoholic beverages are a documented, recurring, and lethal risk in Bali and parts of the broader Indonesian archipelago. Methanol is a byproduct of poorly-distilled fermentation; it is also occasionally added to local spirits to increase apparent alcohol content at lower production cost. Methanol is colourless, odourless, and indistinguishable from ethanol by taste.
Documented Bali incidents: A series of methanol-poisoning deaths in Bali, beginning with documented cases in 2009 and recurring through 2015, 2019, and a cluster in 2023, have resulted in multiple tourist fatalities. The Bali Provincial Health Office has tracked these incidents; they consistently involve local spirits — arak (palm-distilled spirit), tuak (palm wine), or locally-mixed cocktails sold cheaply in tourist-strip bars and warungs. Branded imported spirits (genuine bottled whisky, gin, vodka from reputable producers) do not carry this risk as long as the bottle seal is intact; counterfeit branded spirits in refilled bottles do carry it.
Symptoms of methanol poisoning: The critical window is 12–24 hours after ingestion, when the metabolic byproduct (formic acid) begins accumulating. Initial symptoms are similar to ethanol intoxication. The distinctive marker is that visual disturbances (blurred vision, perceived light flashes, or sudden blindness) appear as the formic acid affects the optic nerve — this is an emergency signal. Other symptoms include severe abdominal pain, nausea, and respiratory difficulty.
Emergency response: Go directly to the nearest hospital emergency department. The treatments — ethanol IV (which competes with methanol for the metabolic enzyme ADH) and fomepizole (the specific antidote) — are effective only if administered before severe metabolic acidosis sets in. Do not wait for symptoms to resolve. BIMC Hospital (Bali International Medical Centre) in Kuta and Siloam Hospital in Denpasar are both equipped to treat methanol poisoning.
Prevention: Do not drink arak, tuak, or locally-mixed cocktails in budget-end bars or warungs in Bali. Check bottle seals on any spirits. In other parts of Indonesia, the methanol risk in local spirits is regional: documented incidents have occurred in North Sulawesi (with sopi), parts of East Nusa Tenggara, and rural Java. The risk correlates with local-production spirits in settings with no quality controls.
Cannabis — the regional legal patchwork
The most operationally dangerous cannabis misconception in Asia is the assumption that Thailand's 2022 decriminalisation applied continuously or applies regionally. It does not.
Thailand 2022–2024 cycle: In June 2022, the Thai government removed cannabis from its Category 5 narcotics list under the Narcotics Act B.E. 2522 (1979), allowing cultivation and sale of cannabis products without THC content above 0.2%. This created a brief period (approximately 2022–2024) during which cannabis dispensaries operated openly in Bangkok, Phuket, and other tourist areas. In 2024, the government reversed course with the Narcotic Drug Act Amendment B.E. 2567 (2024), which reinstated cannabis as a controlled substance for recreational purposes. The enforcement posture as of mid-2026 is still settling, but recreational cannabis is once again legally problematic. Products with less than 0.2% THC (CBD products) remain legal.
Cambodia: Technically illegal but enforcement against tourists for personal quantities is minimal in practice as of 2026. However, "minimal in practice" is an empirical assessment, not a legal protection, and enforcement is subject to change. The specific risk is opportunistic enforcement by police or fake-police as a shakedown pretext — possession of cannabis gives the enforcement agent something to claim.
Rest of the region: Cannabis is illegal in all other countries covered by this site. This includes Japan (Cannabis Control Act, amended 2023), Korea (Narcotics Control Act), Singapore (Misuse of Drugs Act — possession is a criminal offence with severe penalties), Malaysia (Dangerous Drugs Act 1952 — possession above 200g triggers a trafficking presumption and mandatory death penalty), Indonesia (Narcotics Law 35/2009), and all other jurisdictions. The legal risk is not uniformly enforced but is uniformly real.
Other recreational substances
Yaba (methamphetamine tablets): Prevalent in Thai border areas, particularly along the Myanmar border (Chiang Rai, Mae Sai, Mae Sot corridors). Yaba is a methamphetamine/caffeine tablet. In Thailand it is a Category 1 narcotic. Tourists do not typically encounter it in Bangkok or beach-resort contexts, but it is occasionally offered in the context of adult-entertainment encounters in northern Thailand. The Thailand-Myanmar border is the primary source of yaba production for the broader Asian market.
Ketamine: Documented prevalence in Hong Kong club scenes, where it has been a consistent feature of nightlife substance culture since the early 2000s. Ketamine is a Class A dangerous drug under Hong Kong's Dangerous Drugs Ordinance (Cap 134); possession is a criminal offence. It also appears in Bali and Bangkok nightlife contexts. The specific adult-travel risk is twofold: possession exposure, and its use as a drink-spiking agent (ketamine is water-soluble, colourless, and tasteless in dilute form).
MDMA: Documented in Bali and Phuket party-strip contexts. MDMA is a Category 1 narcotic in Thailand and a Category I narcotic in Indonesia. In Bali, street-supply MDMA has been documented as adulterated with methamphetamine, piperazine, and other compounds (by Indonesian drug-testing NGOs including Rumah Cemara). The combination of uncontrolled purity and the physical heat/dehydration context of outdoor parties in tropical environments (Bali Full Moon parties, Phuket beach clubs) is the highest-documented-risk recreational MDMA context in the region.
Singapore Misuse of Drugs Act — the regional extreme
Singapore's Misuse of Drugs Act (Chapter 185, 1973, substantially amended in 1998 and since) is the most aggressive drug law in the region and one of the most severe globally. Key points:
- Mandatory death penalty for trafficking above defined thresholds: heroin above 15g, cocaine above 30g, MDMA above 250g, cannabis above 500g. These are net weight thresholds, not purity thresholds.
- Presumption of trafficking: possession above the trafficking threshold creates a legal presumption of intent to traffic; the accused must rebut this presumption, not the prosecution prove it.
- Caning: mandatory for possession offences above specified quantities for certain drug classes.
- Urine testing: Singapore police can require urine testing on reasonable suspicion. A positive test for controlled substances is itself an offence under the MDA (consumption charge) even in the absence of physical possession. Consumption can be charged based on a test conducted after return from abroad; this provision has been used to charge Singapore residents for drug use during overseas trips.
- Foreign nationals are not exempt. Singapore has executed foreign nationals from multiple countries including Australia, Malaysia, the Netherlands, and Nigeria for drug-trafficking offences.
Country-by-country drug-law quick reference
| Country | Cannabis | MDMA / Stimulants | Opiates | Prescription controls |
|---|---|---|---|---|
| Thailand | Re-criminalised: Narcotic Drug Act Amendment B.E. 2567 (2024) restored cannabis to the Category 5 narcotics list for recreational purposes following the 2022 delisting. Cannabis-derived products with less than 0.2% THC remain legal. Enforcement posture as of 2026 is still settling. | Category 1 narcotic. Severe. Possession: 1–10 years; trafficking: 4–15 years to death depending on quantity. | Category 1 (heroin) and Category 2 (morphine, codeine-containing products). Severe penalties. Methadone available through licensed treatment programs. | Generally permissive for common medications with valid prescription. Controlled-substance imports require Thai FDA permit. |
| Philippines | Illegal. Republic Act 9165 (Comprehensive Dangerous Drugs Act, 2002). Possession of any amount is criminal. | Illegal under RA 9165. 'Dangerous drugs' category; life imprisonment for trafficking; death penalty was removed in 2006 but sentences remain severe. | Illegal except by prescription for medical use. High-profile 'war on drugs' enforcement remains active. | Strict. Controlled substances including tramadol, codeine combinations require Philippine prescription. |
| Vietnam | Illegal. Prohibited under the Penal Code 2015 (as amended). Possession: administrative or criminal depending on quantity. | Prohibited Substance List (Decree 57/2022). Severe penalties; trafficking can reach life imprisonment or death. | Heroin illegal; methadone maintenance therapy available in licensed clinics. Criminal penalties for heroin possession remain severe. | Codeine-containing medications available with prescription. Tramadol now prescription-only. Bring documentation for controlled prescriptions. |
| Indonesia | Illegal under Narcotics Law No. 35/2009, Category I. Maximum 12 years for possession; death penalty for trafficking above threshold quantities. | Category I narcotic. Maximum death penalty for trafficking; 4–12 years for possession. | Category I (heroin). Maximum death penalty for trafficking. Indonesia has executed foreign nationals for drug trafficking. | Controlled substances require Indonesian prescription. Tramadol available OTC in some pharmacies but increasingly controlled. |
| Japan | Illegal under Cannabis Control Act (amended 2023 to add consumption as an offence). Up to 7 years for possession; up to 10 for trafficking. | Stimulant Drugs Control Law (覚醒剤取締法); also Narcotics and Psychotropics Control Law. MDMA: up to 7 years possession, up to 10 years trafficking. | Narcotics and Psychotropics Control Law. Heroin illegal; severe penalties. Codeine and tramadol controlled; Adderall (amphetamine salts) classified as stimulant — illegal to import or possess. | CRITICAL: Adderall, Vyvanse, and Ritalin are stimulants under the Stimulant Drugs Control Law and are ILLEGAL to bring into Japan regardless of home-country prescription. Codeine combinations and tramadol require advance import certificate. Check with Japanese Embassy before travel. |
| Cambodia | Technically illegal under Drug Law 1997. Enforcement is extremely uneven; openly sold in some tourist contexts. Risk of opportunistic enforcement, especially targeting foreigners. | Illegal under Drug Law 1997. Moderate-to-severe penalties. Enforcement is variable but increasing with Chinese investment pressure. | Illegal. Penalties severe in theory; enforcement variable. | Generally permissive in practice; import regulations exist but enforcement for personal quantities is low. |
| South Korea | Illegal under Narcotics Control Act (마약류 관리에 관한 법률). Foreigners have been prosecuted for cannabis use abroad (extraterritorial provision applies to Korean nationals; applicability to foreigners is under their domestic stay). | Psychotropic substance under Narcotics Control Act. Severe: 1 year to life depending on quantity. | Schedule I (heroin). Severe penalties. Codeine available prescription-only. | Amphetamine-class ADHD medications (Adderall, Vyvanse) are illegal. Bring documentation for benzodiazepines, opioids, and tramadol. |
| Taiwan | Illegal under Narcotics Hazard Prevention Act (毒品危害防制條例). Schedule 2 narcotic. Up to 3 years for possession; severe trafficking penalties. | Schedule 2. Up to 3 years possession; up to 10 years trafficking. | Schedule 1 (heroin): severe. Methadone maintenance therapy available. | Controlled substances (opioids, benzodiazepines) require Taiwanese prescription or advance registration for import. |
| Singapore | Misuse of Drugs Act (Cap 185). Possession: up to 10 years and/or fines. Trafficking above 500g: MANDATORY DEATH PENALTY. | Class A drug under MDA. Possession: up to 10 years; trafficking above threshold: mandatory death penalty. | Class A. Heroin trafficking above 15g: MANDATORY DEATH PENALTY. Possession: up to 10 years. | Strict. Controlled medicines (codeine above 30mg, tramadol, benzodiazepines, ADHD medications) require prior authorisation from Health Sciences Authority. Apply at least 10 working days before travel. |
| Malaysia | Dangerous Drugs Act 1952. Possession of 200g or more: PRESUMED TRAFFICKING — DEATH PENALTY. Possession below threshold: up to 5 years. | Dangerous Drugs Act 1952. Above threshold: mandatory death penalty. Below threshold: severe. | Heroin above 15g: MANDATORY DEATH PENALTY. Malaysia has actively executed both nationals and foreigners for drug trafficking. | Controlled medicines require Malaysian prescription or advance import authorisation. ADHD medications (amphetamine class) are illegal. |
| Hong Kong | Dangerous Drugs Ordinance (Cap 134). Possession: up to HKD 1 million and 7 years; trafficking: life imprisonment. | Class A dangerous drug. Possession: severe; trafficking: up to life imprisonment. | Heroin: Class A. Severe penalties. Methadone programme operated by DH. | Controlled substances require HK prescription or import licence. Bring originals, not photocopies. |
| India | Narcotic Drugs and Psychotropic Substances Act, 1985 (NDPS Act). Cannabis resin (charas) and flowering/fruiting tops (ganja): illegal and criminally penalised. Bhang (leaves and seeds) is excluded from NDPS and variously regulated at state level. Significant enforcement variation by state and context. | NDPS Act Schedule I psychotropic substance. Commercial quantity: 10–20 years; trafficking: severe. | Heroin: NDPS commercial quantity — 10–20 years mandatory minimum. Opium/morphine: controlled medical use. India is a significant licit opium producer; illicit market penalties severe. | Codeine combinations (including popular cold medicines) are Schedule H1 in India and increasingly controlled. Tramadol is Schedule H1. ADHD medications require psychiatrist prescription. |
| China | Narcotic Drug Regulations 2005. Illegal. Administrative detention for personal use; criminal prosecution for dealing. Foreign nationals detained for cannabis: administrative deportation common but criminal prosecution possible. | Psychotropic substance under the 2005 regulations. Trafficking: up to life imprisonment or death for large quantities. | Heroin: death penalty for trafficking. Fentanyl and analogues: strict new controls since 2019. | Bring original prescriptions with official English translation. Controlled substances (opioids, ADHD medications) require advance registration with Chinese customs. |
| Macau | Prohibited under Law 17/2009, Macau's consolidated drug-control statute. Personal possession of any quantity is a criminal offence; there is no medical or CBD carve-out equivalent to Thailand's 0.2% THC threshold. Enforcement is active given Macau's casino-tourism profile and heavy police presence around gaming areas; foreign nationals have been prosecuted for possession discovered during routine hotel or border checks. | Severely criminalised under the same Law 17/2009 framework; MDMA falls in the higher-penalty schedule alongside other synthetic drugs, with trafficking-threshold quantities treated as aggravated offences carrying multi-year sentences. | Prohibited; heroin and other opiates fall in the most severely penalised schedule under Law 17/2009. The Judicial Police (PJ) treat opiate trafficking as a priority target given transnational supply routes through the Pearl River Delta. | Prescription medications are permitted with a valid prescription and customs declaration for controlled substances; carry original pharmacy labelling and physician documentation, particularly for opioid-class or benzodiazepine medications, given close coordination with mainland Chinese customs controls at the land border crossings. |
| Sri Lanka | Illegal under the Poisons, Opium and Dangerous Drugs Ordinance 1935 as amended, where cannabis is classified in Category B alongside other controlled narcotics. Possession, cultivation and sale are all criminal offences. Enforcement against foreign tourists for small personal quantities does occur, particularly in beach-town nightlife areas along the southern coast, and is a documented arrest category distinct from the adult-industry risks covered elsewhere on this page. | Prohibited under the same Ordinance framework; MDMA is treated as a dangerous drug with severe statutory penalties, though enforcement capacity and consistency have been affected by the 2022 economic crisis and resulting resource constraints within the police service. | Opium and heroin are historically documented issues concentrated in the north of the island, a legacy in part of civil-war-era supply routes; penalties are severe on the statute book. The death penalty remains on the books for serious drug-trafficking offences but has not been carried out in Sri Lanka in decades, making the practical exposure closer to long-term imprisonment. | Prescription medications generally require documentation on entry; codeine and other controlled preparations should be carried in original packaging with a physician's letter. Import regulations exist but enforcement for small personal quantities of common prescription medicines is not a high-frequency risk in practice. |
| Laos | Formally illegal under the Penal Code 2017's narcotics provisions, though enforcement has historically operated in a grey zone in some rural and tourist contexts. Vang Vieng's backpacker-era tolerance has narrowed significantly since the 2012-2013 government crackdown, and cannabis possession is not a low-risk activity for foreign visitors in the way it briefly was in pre-2024 Thailand. | MDMA is prohibited and penalised under the 2017 Penal Code's narcotics framework, but the more significant public-health and enforcement concern in Laos is methamphetamine — locally yaba — which is a major and growing issue, particularly along northern border and trafficking corridors linked to the broader Mekong methamphetamine trade. | Heroin and other opiates are prohibited with severe statutory penalties. Laos sits within the broader Golden Triangle production and transit geography, and opiate-trafficking enforcement is a stated government and international-cooperation priority, though domestic treatment infrastructure remains limited outside Vientiane. | Foreign visitors carrying prescription medications, particularly opioid-class or stimulant medications, face strict scrutiny; Laos applies its narcotics framework with limited flexibility for undocumented controlled substances, and travellers should carry original prescriptions and physician letters, especially given the country's comparatively thin consular and legal-aid infrastructure for foreigners facing drug charges. |
| Nepal | Illegal under the Narcotic Drugs (Control) Act 1976, but cannabis occupies a distinctive cultural position in Nepal: its use is historically tolerated in a religious context, particularly around the Maha Shivaratri festival at Pashupatinath Temple in Kathmandu, when sadhus and pilgrims openly consume cannabis. This cultural tolerance does not extend to a general legal exemption, and enforcement against foreign tourists is irregular — ranging from ignored to prosecuted depending on location and circumstance. | MDMA is severely penalised under the 1976 Act's psychotropic-substance provisions, with no cultural-tolerance carve-out equivalent to cannabis; trafficking-quantity offences carry lengthy prison terms. | Heroin and other opiates are severely penalised under the same statute; opiate use is a documented public-health concern in Kathmandu Valley, and enforcement against foreign nationals involved in heroin possession or trafficking is significantly more aggressive than the cannabis-enforcement pattern. | Controlled prescription medications require documentation; Nepal's customs and police enforcement capacity outside Kathmandu and Pokhara is limited and inconsistent, which cuts both ways for travellers — lower routine scrutiny but less predictable outcomes if a problem does arise. |
| Bangladesh | Cannabis (locally ganja) is illegal under the Narcotics Control Act 2018, which replaced the 1990 Narcotics Control Act, yet remains widely available and culturally normalised in parts of Bangladesh, particularly in rural areas and around certain religious shrine contexts. The gap between formal illegality and informal availability does not reduce legal exposure for foreign visitors, who face the same statutory penalties as any other offender. | MDMA and other synthetic drugs are severely penalised under the 2018 Act, which is markedly stricter than its 1990 predecessor and was enacted partly in response to the methamphetamine (yaba) crisis affecting Bangladesh via the Myanmar border. | Heroin and other opiates carry severe penalties under the 2018 Act, which introduced new death-penalty provisions for large-quantity trafficking offences — a significant escalation from the 1990 framework. Foreign nationals are not exempt from these provisions. | Prescription medication import requires documentation; codeine and other controlled preparations should be carried in original packaging with physician letters. Enforcement infrastructure for foreign visitors is thin outside Dhaka, consistent with Bangladesh's generally low leisure-tourism volume. |
| Mongolia | Illegal under the Criminal Code 2015's narcotics provisions (Article 20.1 and following). Possession and use are criminal offences with no medical or CBD carve-out; enforcement in Ulaanbaatar is active but the overall drug-enforcement apparatus is smaller in scale than in Southeast Asian counterparts given Mongolia's low population density and limited leisure-tourism volume. | MDMA is prohibited under the same 2015 Criminal Code framework; penalties are substantial but Mongolia's overall drug-law enforcement posture is relatively less severe than its Southeast Asian neighbours, with sentencing generally falling short of the mandatory-death-penalty regimes seen in Singapore or Malaysia. | Heroin and synthetic opiates are prohibited, and Ulaanbaatar has documented a growing synthetic-drug and opiate problem since the 2010s mining-boom period, linked to increased disposable income and expanded trafficking routes through China and Russia. | Controlled prescription medications require documentation on entry; Mongolia's customs enforcement is less intensively resourced than China's or Russia's, but travellers should still carry original prescriptions and physician letters for opioid-class, benzodiazepine, or stimulant medications given inconsistent border-post practices outside Ulaanbaatar's main airport. |
Prescription medication in Asia
Medications that are legal and commonly prescribed in home countries can be controlled substances or outright illegal in Asian destinations. The consequences of carrying controlled medications without documentation range from confiscation to criminal charges. Key cases:
- Japan — ADHD medications: Adderall (mixed amphetamine salts), Vyvanse (lisdexamfetamine), and Ritalin (methylphenidate) are classified as stimulants under Japan's Stimulant Drugs Control Law (覚醒剤取締法). They are illegal to bring into Japan regardless of a home-country prescription. This is not a documentation problem; it is a legal prohibition. Travellers with ADHD should consult their prescribing physician about alternatives (atomoxetine, Strattera, is legal in Japan) or about managing without medication during the trip.
- Japan — codeine combinations: Common cold medicines containing codeine (e.g., certain UK codeine phosphate preparations, some US OTC cough syrups) are controlled under Japan's Narcotics and Psychotropics Control Law. Bringing a 30-day personal supply of codeine-containing medication requires an advance import certificate (申請書) from the Ministry of Health, Labour and Welfare.
- Singapore — codeine and tramadol: Codeine preparations above 30mg and tramadol require prior authorisation from Singapore's Health Sciences Authority. A standard UK Solpadeine Max (12.8mg codeine) is under the threshold; a standard UK co-codamol 30/500 is above it. Tramadol is a prescription medicine requiring authorisation.
- Malaysia — ADHD medications: Amphetamine-class ADHD medications are illegal. Methylphenidate (Ritalin) is controlled; possession without Malaysian prescription may constitute an offence under the Dangerous Drugs Act 1952.
The general framework for carrying controlled medications legally is: (1) carry a maximum 30-day supply; (2) carry the original pharmacy-labelled container, not a pill organiser; (3) carry a signed letter from your prescribing physician on letterhead; (4) for Japan and Singapore specifically, apply for advance import authorisation through the relevant health ministry before travel — not at the airport. The specific authorisation process is described on the Japanese Ministry of Health, Labour and Welfare website (English language) and the Singapore HSA website.
If someone overdoses
The instinct to manage an overdose without calling emergency services — because of concern about legal exposure — is a documented cause of preventable deaths in Asia. Understanding the actual legal framework helps:
- Most countries in Asia have no "Good Samaritan" drug protection law. The US's 911 Immunity laws and the UK's partial Good Samaritan framework do not have direct equivalents in Thailand, the Philippines, Indonesia, Vietnam, Cambodia, or India. This means that calling emergency services when someone overdoses does carry some risk of police involvement.
- Singapore and Hong Kong are partial exceptions. Singapore Police Force guidance (published 2020) states that the primary response to overdose should be medical intervention; in practice, police attendance at an overdose scene in Singapore is more likely to focus on the overdose victim's welfare than on arresting bystanders. Hong Kong has a similar pragmatic enforcement posture, though no formal immunity provision.
- The correct response regardless: call the emergency number (see table below), describe the symptoms, state the suspected substance if known, follow the dispatcher's instructions. For opioid overdose: slow or stopped breathing, pinpoint pupils, unconsciousness — this is the life-threatening presentation; naloxone (Narcan) is available OTC at pharmacies in Thailand; in other countries it requires a prescription. For stimulant overdose (MDMA, methamphetamine): hyperthermia (extremely high body temperature) is the specific killer — cool the person, call emergency services, do not leave them alone. For GHB overdose combined with alcohol: respiratory depression — recovery position if unconscious, call emergency services immediately.
Emergency numbers: Thailand 1669; Philippines 911; Vietnam 115; Indonesia 119; Japan 119; Cambodia 119; South Korea 119; Taiwan 119; Singapore 995; Malaysia 999; Hong Kong 999; India 112; China 120.
See also: Scam catalogue for drink-spiking in the context of theft; Emergencies for detention response if stopped by police; and before you go for prescription-documentation preparation.