Mephedrone (4-MMC): general

Mephedrone (4-MMC) is a synthetic cathinone [1], a ring-substituted analogue of methcathinone [2], structurally related to the parent compound cathinone, the β-keto analogue of amphetamine [3]. It sits in the stimulant effect group [4] and, historically, appeared on the street drug market as a substitute for MDMA [3]. It's usually sold as a powder or as tablets [1], and has been used orally, by nasal insufflation, by intramuscular or intravenous injection, and rectally [1].

There is no dose, onset, or duration information in this reference. If you're using anyway, that gap is itself the guidance: start with a small test dose [5], stay hydrated [5], don't mix with alcohol or other stimulants [5], and don't use alone [5].

As with stimulants generally, overdose doesn't look the same in every case — it depends on medical history, the specific stimulant, route, and dose [6], and it can escalate to cardiovascular collapse, multiorgan failure, and death [7]. If that happens, the response is supportive care: cooling, sedation, cardiovascular support [8]. Chest pain, seizure, or extreme agitation in yourself or someone else means it's time to get help [5].

Mephedrone's abuse liability carries a substantial risk to public health and society [2], and no therapeutic use has been recorded for it [2]. It is controlled under Schedule II of the 1971 Convention [4], and in the United States it is a DEA Schedule I substance, meaning it's treated as having no accepted medical use, a lack of accepted safety for use under medical supervision, and high potential for abuse [9].

References

1. In accordance with Article 5 of Council Decision 2005/387/JHA on the information exchange, risk assessment and control of new psychoactive substances — Europol / EMCDDA
2. Mephedrone - Expert Committee on Drug Dependence Information Repository — World Health Organization
3. Clinical Pharmacology of the Synthetic Cathinone Mephedrone — PubMed / Taylor & Francis
4. Substance Details 4-Methylmethcathinone — United Nations Office on Drugs and Crime
5. Harm reduction and methamphetamine use — NSW Health
6. Stimulant Guide: Overdose Prevention and Response — Centers for Disease Control and Prevention
7. Sympathomimetic Toxicity – StatPearls — NCBI Bookshelf
8. SAMHSA Overdose Prevention and Response Toolkit — Substance Abuse and Mental Health Services Administration
9. Mephedrone | C11H15NO | CID 45266826 - PubChem — National Library of Medicine