Caffeine provokes adverse interactions with 3,4‐methylenedioxymethamphetamine (MDMA, ‘ecstasy’) and related psychostimulants: mechanisms and mediators

Consuming caffeine with recreational psychostimulant drugs like MDMA (ecstasy) can cause severe acute adverse reactions and long-term harm. Caffeine increases toxicity by disrupting body temperature regulation, causing heart damage, and lowering the seizure threshold. In rats, co-administering caffeine with MDMA dramatically raises core body temperature, heart rate, and death rates, and worsens long-term damage to serotonin neurons. The interaction involves MDMA boosting dopamine release while caffeine blocks adenosine receptors and inhibits PDE. Similar mechanisms apply to interactions with cocaine, d-amphetamine, and ephedrine. Understanding these mechanisms helps guide interventions for managing severe reactions and drug-related toxicity from combined caffeine and psychostimulant use.

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Abstract

Concomitant consumption of caffeine with recreational psychostimulant drugs of abuse can provoke severe acute adverse reactions in addition to longer term consequences. The mechanisms by which caffeine increases the toxicity of psychostimulants include changes in body temperature regulation, cardiotoxicity and lowering of the seizure threshold. Caffeine also influences the stimulatory, discriminative and reinforcing effects of psychostimulant drugs. In this review, we consider our current understanding of such caffeine‐related drug interactions, placing a particular emphasis on an adverse interaction between caffeine and the substituted amphetamine, 3,4‐methylenedioxymethamphetamine (MDMA, ‘ecstasy’), which has been most recently described and characterized. Co‐administration of caffeine profoundly enhances the acute toxicity of MDMA in rats, as manifested by high core body temperature, tachycardia and increased mortality. In addition, co‐administration of caffeine enhances the long‐term serotonergic neurotoxicity induced by MDMA. Observations to date support an interactive model of drug‐induced toxicity comprising MDMA‐related enhancement of dopamine release coupled to a caffeine‐mediated antagonism of adenosine receptors in addition to inhibition of PDE. These experiments are reviewed together with reports of caffeine‐related drug interactions with cocaine, d‐amphetamine and ephedrine where similar mechanisms are implicated. Understanding the underlying mechanisms will guide appropriate intervention strategies for the management of severe reactions and potential for increased drug‐related toxicity, resulting from concomitant caffeine consumption.