Mephedrone
4-MMC · meow meow · m-cat
What does current UK evidence show?
UK submitted-sample intelligence remains important because products sold as mephedrone may contain another cathinone. Individual detections cannot describe the wider market.
Overview
Identity, legal classification, form and pharmacological context
- Drug category
- Stimulants · Synthetic drugs
- Common names
- 4-MMC, meow meow, m-cat
- Typical forms
- Usually white or off-white powder or crystals; capsules and tablets may also occur
- Routes
- Most commonly snorted or swallowed; injecting is less common and carries additional risks
- UK legal classification
- Class BMephedrone is covered by the Class B control of cathinone derivatives.Check government source ↗
- Concise pharmacology
- Mephedrone is a synthetic cathinone stimulant affecting monoamine signalling; its effects and routes should not be assumed identical to those of every cathinone.
Main harms
Concise clinical and polydrug picture
Agitation, overheating, rapid heart rate, chest pain and seizures can occur, especially with repeated use or combinations.
Repeated use can be associated with dependence, mood and sleep problems; long-term evidence for mephedrone specifically remains limited.
Fatigue, low mood, sleep disturbance and craving can follow sustained use.
Other stimulants increase cardiovascular and overheating risks; alcohol and depressants can obscure impairment.
Snorting can irritate or damage nasal tissue; injecting adds infection and blood-borne virus risks. Products sold as mephedrone may contain another cathinone.
Current intelligence status
Assessment, confidence and direction
UK submitted-sample intelligence remains important because products sold as mephedrone may contain another cathinone. Individual detections cannot describe the wider market.
Reason: Sparse or selected evidence supports only this narrow assessment; the wider market and trend remain uncertain.
Principal source limits: Submitted samples confirm their own contents but cannot estimate prevalence or represent the wider drug supply. Household survey for England and Wales; it under-represents some high-risk populations and does not cover the whole UK.
Geography and reference periods are given in each linked source card below. The rating is an editorial evidence judgement, not a probability, clinical risk score or TD priority.Signals justify continued monitoring, but current evidence does not support a formal escalation assessment.
Operational implications
Evidence-supported prompts for professional response
Use contents-first communication, analytical testing and stimulant-toxicity pathways rather than relying on the product name.
Record substance, sold identity, route, frequency and combinations; review physical, mental-health and dependence needs.
Use symptom-led assessment and escalate reduced consciousness, seizures, overheating, chest pain or severe agitation.
Send unexpected products or incidents through agreed testing and alert routes; distinguish confirmed results from preliminary reports.
Related intelligence
Continue into connected platform evidence
Sources & limitations
Direct evidence links, reference periods and status
Welsh Emerging Drugs and Identification of Novel Substances
PublishedContinuousReference periodSubmitted samples
Submitted samples confirm their own contents but cannot estimate prevalence or represent the wider drug supply.Drug misuse in England and Wales
Published11 Dec 2025Reference periodYear ending March 2025
Household survey for England and Wales; it under-represents some high-risk populations and does not cover the whole UK.Synthetic cathinones: updated harms assessment
Published3 Feb 2025; response added 10 Sep 2026Reference periodUK analytical and clinical evidence
Individual cathinones and their routes differ; a sold name may not identify a compound.