Psychoactive Synthetic Adulterants in Tablets Sold as MDMA after the COVID-19 Pandemic: Implications for Central Effects.

Tablets sold as MDMA frequently contain psychoactive adulterants that vary by region and year, potentially increasing central nervous system harm. A review of studies from 2020 to 2025 covering Continental Europe, the UK, the USA, and Australia found that co-administration of MDMA with common adulterants can exacerbate noxious neurological and psychiatric effects. The composition of tablets differs across these regions, and interactions between MDMA and adulterants may explain some adverse effects seen in users. Expanding drug checking and public health efforts is essential to inform users, first responders, and healthcare professionals about these risks.

Study at a glance

Abstract

Preclinical and clinical studies reported that 3,4-methylenedioxymethamphetamine (MDMA, 'ecstasy') can cause adverse effects in the central nervous system (CNS). Recently, preclinical studies have demonstrated that certain psychoactive substances may exacerbate the noxious central effects of MDMA when co-administered, including substances that are contained as adulterants in tablets sold as MDMA in the illegal market. Since the quality and quantity of adulterants in tablets sold as MDMA vary based on factors, such as the year and the geographical region of production, this may result in diverse health risks for people who use MDMA. This review provides a concise overview of: i) composition of tablets sold as MDMA in Continental Europe, UK, USA and Australia in the post COVID-19 pandemic period; ii) recent preclinical and clinical findings about the central effects of the psychoactive adulterants most commonly found in tablets sold as MDMA in the above areas; and iii) the possible adverse CNS effects of these adulterants in humans when taken in combination with MDMA. We systematically searched PubMed, Scopus, and Web of Science for studies published between 2020 and 2025 using terms related to "adulterants", "MDMA tablets composition," "COVID-19". Eligible articles were screened for quality, with emphasis on recent, high-impact contributions. Extracted papers included cytotoxicity studies, neurobehavioral outcomes, and mechanistic insights. Tablets sold as MDMA are frequently and differently adulterated in Continental Europe, the UK, the USA, and Australia. The possible interactions between MDMA and psychoactive adulterants contained in tablets sold as MDMA deserve attention, since they may potentially explain some of the noxious neurological and psychiatric effects that have been described in people who use MDMA. Ongoing public health efforts and expansion of drug checking are essential to properly inform MDMA users about the risks associated with psychoactive contaminants, first responders, healthcare professionals, and the general public about the possible detrimental consequences for health associated with the use of MDMA obtained from illicit sources and unintended contaminant consumption.