De umiddelbare negative virkninger af MDMA-brug kan omfatte:
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* [[Dehydrering]]<ref name="pmid22392347"/><ref name="Acute amph toxicity" /><ref name="Hyponatremia" />
* [[Hypertermi]]<ref name=Betzler2017/><ref name="pmid22392347" /><ref name="Hyponatremia" />
* [[Bruxisme]] (slibning og sammenbidning af tænder)<ref name=Betzler2017/><ref name="pmid22392347" /><ref name=Current2013 />
* Øget vågenhed eller [[søvnløshed]]<ref name=Betzler2017/><ref name="Acute amph toxicity" />
* Øget sved og svedtendens<ref name="Acute amph toxicity" /><ref name="Hyponatremia" />
* Øget puls og [[blodtryk]]<ref name=Betzler2017/><ref name="pmid22392347" /><ref name="Hyponatremia" />
* Øget psykomotorisk aktivitet<ref name=Betzler2017/>
* Tab af appetit<ref name=Betzler2017/><ref name="Toxnet MDMA after-effects"/>
* Kvalme og opkastning<ref name=Current2013 />
* [[Diarré]]<ref name="Acute amph toxicity" />
* [[Impotens]]<ref name=Betzler2017/><ref>{{cite journal | vauthors = Spauwen LW, Niekamp AM, Hoebe CJ, Dukers-Muijrers NH | title = Drug use, sexual risk behaviour and sexually transmitted infections among swingers: a cross-sectional study in The Netherlands | journal = Sexually Transmitted Infections | volume = 91 | issue = 1 | pages = 31–6 | date = februar 2015 | pmid = 25342812 | doi = 10.1136/sextrans-2014-051626 | quote = It is known that some recreational drugs (eg, MDMA or GHB) may hamper the potential to ejaculate or maintain an erection. | doi-access = free }}</ref>
* Visuelle og auditive hallucinationer (sjældent)<ref name=Betzler2017/>
{{div col end}}
Kemi