AKA Shrimp:
4-MEC is an illegal stimulant, its chemical name is 4-Methylethcathinone. It is chemically similar to Mephedrone and they are both cathinones. It is a white-powdered amphetamine like substance. It is mainly snorted, sometimes swallowed and acts on the central nervous system. 4-MEC can causes rapid heartbeat but also give a strong sense of well-being. It lasts an hour or more - you feel alert, exhilarated and very talkative. It was marketed and advertised as plant food or bath salts simply to get around medicine and consumer legislation. The price is relatively low (about 10-15 per gram) less than half the cost of cocaine but with much higher purity. It is much less prevalent than M-Cat.

4-MEC:
http://www.wnfo.org.uk/drugs/4-mec/

4-MEC

Duration: A substituted cathinone stimulant; little is known about its safety or subjective effects. It is believed to have similar effects to mephedrone, but with a lower potency and a stronger stimulating character.
Route	Onset	Duration	After Effects
Tripsit Factsheets
4-MEC Basic Information: http://drugs.tripsit.me/4-MEC
Oral:	15-45 minutes	2-5 hours	2-4 hours
Effects: Euphoria, increased energy/alertness, decreased need for sleep, increased sociability, mood lift, increased sexuality, excessive talking, decreased appetite, weight loss, sweating, disturbed sleep patterns, bruxism, visual and auditory hallucinations, itchiness, aggressiveness, moodiness.

World Health Organization 2016:
4-Methylethcathinone (2-(ethylamino)-1-(4-methylphenyl)propan-1-one), also known as 4-MEC, has emerged in recent years as a recreational psychostimulant. Its homolog mephedrone (4-methylmethcathinone) is listed as a Schedule II substance under the 1971 United Nations Convention on Psychotropic Substances.The first official notification submitted to the European Monitoring Centre for Drugs and Drug Addiction (EMCDDA) by a European member state was 2010. Since then it has been detected across the globe and marketed as a "research chemical" although it has also been detected as a constituent in branded products available for purchase viathe Internet or brick-and-mortar shops.

4-MEC is a psychostimulant with monoamine transporter activity with indications of abuse liability. Some data obtained from the analysis of user reports suggest that 4-MEC produces euphoria, a sense of well being,psychostimulant effects and lack of comedown symptomatology and that these appear to be less intense and short-lived compared to mephedrone. Conflicting information is available related to the urge of redosing, craving and bingeing. Negative effects associated with 4-MEC use include excessive sweating in the armpits, nausea, and vomiting but also jaw clenching, nystagmus, heart palpitations, loss of sightand migraine.

The available data so far also suggest that it may also function as a serotonin releasing agent but not dopamine, which would differentiate it from its homolog mephedrone.

Further studies are needed to assess the dependence potential.The number of case reports that demonstrate a causal relationship between 4-MEC consumption and fatal intoxication is relatively limited.There is no known therapeutic and medical use.

4-Methylethcathinone (4-MEC)Critical Review Report (PDF 38 pages):
https://www.who.int/medicines/access/controlled-substances/4.3_4-MEC_CritReview.pdf?ua=1

4-MEC Summary Sheet:
https://psychonautwiki.org/wiki/Talk:4-MEC

4-Methylethcathinone Experience Reports:
https://www.erowid.org/experiences/subs/exp_4Methylethcathinone.shtml

4-methylethcathinone Monograph (PDF 5 pages):
http://www.swgdrug.org/Monographs/4-MEC.pdf

4-Methylethcathinone (hydrochloride) Safety Data Sheet (PDF 5 pages):
https://www.caymanchem.com/msdss/9001069m.pdf