Nimetazepam
Nimetazepam, sold historically as Erimin and known on the street as Erimin-5 or Happy-5, is a controlled benzodiazepine. A Class C controlled drug and Fourth Schedule specified drug in Singapore, with no named section 17 trafficking threshold.
Overview
Nimetazepam is a benzodiazepine developed as a sedative-hypnotic medicine and marketed in parts of Asia under the Erimin name, including as Erimin 5. It is CAS 2011-67-8, PubChem CID 4496, molecular formula C₁₆H₁₃N₃O₃, and chemically a nitrobenzodiazepinone — IUPAC 1-methyl-7-nitro-5-phenyl-3H-1,4-benzodiazepin-2-one.
The original proprietary product is no longer a normal current medicine: UNODC reports that licit manufacture of Erimin 5 was discontinued in 2015. The name persists in illicit markets, where tablets are sold as <strong>Erimin-5</strong> or <strong>Happy-5</strong> — both names Singapore's Central Narcotics Bureau lists. That gap between a discontinued pharmaceutical and a continuing street name is exactly why this page exists: a reader who meets “Erimin”, “Erimin-5” or “Happy-5” in a judgment needs to be able to resolve it to nimetazepam.
It is controlled in Schedule IV of the United Nations Convention on Psychotropic Substances of 1971. The INCB Green List entry reads: “NIMETAZEPAM — 1,3-dihydro-1-methyl-7-nitro-5-phenyl-2H-1,4-benzodiazepin-2-one”.
Source: PubChem CID 4496; INCB Green List, 36th edition; UNODC, Synthetic Drugs in East and Southeast Asia 2026; Singapore Central Narcotics Bureau.
Chemistry & mechanism of action
Nimetazepam belongs to the benzodiazepine class. Benzodiazepines enhance inhibitory signalling at GABA-A receptors, reducing central nervous system activity and producing sedation, impaired alertness and other depressant effects. Experimental receptor work identified nimetazepam as a high-affinity benzodiazepine-receptor ligand.
Human metabolism studies identify nitrazepam and 7-aminonimetazepam among its metabolites, so a urine screen may detect nitrazepam in someone who took nimetazepam. The two are closely related but distinct compounds and should not be treated as the same drug.
These are class and laboratory findings describing pharmacology. They do not make nimetazepam an approved medicine.
Source: PubChem CID 4496; PubMed 2857046 (benzodiazepine-receptor binding); PubMed 23085494 (metabolism).
Effects
Expected benzodiazepine effects include drowsiness, slowed reactions, impaired judgement, reduced coordination, and memory or concentration problems.
Impairment outlasts the subjective sense of being affected, which is what makes driving and similar tasks dangerous well after someone feels recovered.
Illicit tablets add a separate uncertainty that no description of effects can cover: the name or appearance of a tablet does not establish its actual contents or its strength.
Source: FDA benzodiazepine class boxed-warning update; Singapore Central Narcotics Bureau.
Risks & harms
Risks rise sharply when a benzodiazepine is combined with opioids, alcohol or other central nervous system depressants: profound sedation, respiratory depression, coma and death can occur. This is the substance of the FDA's boxed warning for the whole benzodiazepine class.
Repeated use can lead to physical dependence. Abrupt dose reduction or stopping after dependence has developed can cause serious withdrawal, including seizures. A taper needs a prescriber.
Because genuine Erimin 5 has not been manufactured since 2015, a tablet sold under that name has an unverified identity and an unverified dose. Neither can be established without laboratory analysis.
Source: FDA benzodiazepine class boxed-warning update; UNODC, Synthetic Drugs in East and Southeast Asia 2026.
Legal status (US)
<strong>International.</strong> Nimetazepam is controlled in Schedule IV of the United Nations Convention on Psychotropic Substances of 1971.
<strong>Singapore.</strong> The Misuse of Drugs Act 1973 lists nimetazepam in the First Schedule, Part 3, as a <strong>Class C controlled drug</strong>, and in the Fourth Schedule, item 10, as a <strong>specified drug</strong>. Section 8(a) prohibits unauthorised possession and section 5 addresses trafficking and possession for the purpose of trafficking. Because it is a specified drug, section 8(b)(ii) creates a named consumption offence, and section 8A extends the specified-drug consumption rule to Singapore citizens and permanent residents outside Singapore in the circumstances the Act states.
<strong>Section 17 trafficking presumption: NONE FOUND.</strong> Section 17 lists quantities for opium, morphine, diamorphine, cannabis, cannabis mixture, cannabis resin, cocaine, methamphetamine, ketamine and the MDMA-group compounds. It does not name nimetazepam. <strong>NONE FOUND is not zero.</strong> It means the section 17 presumption is not triggered by any named nimetazepam quantity — not that every quantity triggers it. Trafficking may still be proved by evidence.
<strong>Elsewhere.</strong> Nimetazepam is Schedule IV federally in the United States, Class C in the United Kingdom, Opium Act List II in the Netherlands, BtMG Annex III in Germany, CDSA Schedule IV in Canada, First Schedule Part III under Malaysia's Dangerous Drugs Act, a Category 2 psychotropic in Thailand, Category IV in Indonesia and Schedule 8 in the UAE. Three cautions on quantities: Canada's Schedule IV listing does <em>not</em> bring nimetazepam within the CDSA section 4(1) simple-possession offence; Japan's 150 mg figure and Thailand's prescribed-day rules are <em>traveller administration</em> thresholds, not criminal-law permissions; and Australia has no express Commonwealth Poisons Standard entry — the 25 g pure-drug traffickable quantity is <strong>Victoria only</strong>, from a generic 7-nitro-1,4-benzodiazepine entry, and is not a national rule.
This section is under editorial and legal review. Verify the position in the specific jurisdiction before relying on it.
Source: Misuse of Drugs Act 1973, First Schedule Part 3, Fourth Schedule item 10, ss 5, 8, 8A and 17 (Singapore Statutes Online, current version); INCB Green List 36th edition; 21 CFR 1308.14(c)(42); Misuse of Drugs Act 1971 Sch 2 Pt III; Opiumwet List II; BtMG Anlage III; CDSA Sch IV; Dangerous Drugs Act 1952 First Schedule Pt III; Thai Narcotics Code B.E. 2564; Indonesian MoH Reg 10/2022; UAE Federal Decree-Law 30/2021 Sch 8; Drugs, Poisons and Controlled Substances Act 1981 (Vic) Sch Eleven Pt 1.
Drug laws and enforcement change and vary by country. This is not legal advice. Always confirm with the destination’s embassy or official drug authority before traveling — penalties can be severe, including imprisonment.
Before you travel
Verify current rules with the destination country’s official drug authority and your own country’s embassy before traveling. Find the destination’s U.S. embassy & official country guidance →
Non-U.S. travelers: check your own government’s travel advisory and embassy.
If you’re detained or arrested abroad
Contact your own country’s embassy or consulate in the destination immediately — not the destination’s authorities. U.S. citizens: contact the nearest U.S. embassy/consulate and the U.S. State Department at +1-202-501-4444 (from abroad). If a U.S. citizen is arrested or detained abroad →
Images
Visual references coming soon.
If it’s too intense
If an experience becomes overwhelming, the goal is to stay safe and let it pass, most difficult experiences ease as the drug wears off.
- Get to a calm, safe space with someone you trust who is sober and can stay with you.
- Cool down if you’re overheating, move somewhere cool, remove extra layers, rest. Overheating is especially a risk with stimulants and MDMA.
- Sip water to thirst, but don’t over-hydrate. Drinking large amounts of plain water (especially after MDMA) can dangerously dilute your blood sodium (hyponatremia). Electrolytes help more than volume.
- Slow your breathing, long, slow exhales help settle a racing heart and anxiety.
- A sugary drink, fruit juice, or a snack can ease shakiness and the anxiety that comes with low blood sugar.
- Do not take more, and do not add another substance to manage it. Redosing or adding something else (including a sedative like a benzodiazepine) can make things worse, not better.
With depressants, the danger is over-sedation: if someone is very drowsy, hard to wake, or breathing slowly, treat it as an emergency.
Source: general harm-reduction guidance from SAMHSA, NIH/NIDA, and MedlinePlus, in our own words. Draft, not yet medically reviewed.
Dosage
Pending medical reviewer
Sources
- Singapore — Misuse of Drugs Act 1973, First Schedule
- Singapore — Misuse of Drugs Act 1973, Fourth Schedule
- Singapore — Misuse of Drugs Act 1973, s 17 (trafficking presumption)
- INCB — Green List, 36th edition
- UN Convention on Psychotropic Substances 1971
- PubChem — Nimetazepam, CID 4496
- FDA — benzodiazepine class boxed-warning update
- Singapore Central Narcotics Bureau — nimetazepam
- UNODC — Synthetic Drugs in East and Southeast Asia 2026