In recent years mephedrone (4-methylmethcathinone) has gained popularity over other classified recreational drugs of abuse due to its low price and availability on the Internet. Because of its unwanted toxic and possibly lethal effects it is currently a matter of concern to public health worldwide. The significant qualitative and quantitative variation in content of the purportedly mephedrone-containing products on the market as well as the tendency to assume mephedrone combined with other drugs is challenging in terms of analytical identification in both street and biological samples. Furthermore, the many possible mephedrone-based combinations limit the possibilities of narrowing the clinical presentation of mephedrone intoxication, hence impairing the effectiveness of medical intervention. For these reasons awareness on the matter of mephedrone recreational use is necessary among clinicians and forensic scientists and, at least, the most common compounds derived from the combination of mephedrone and other substances should be included in toxicology screening procedures. © 2016 Elsevier Inc. All rights reserved.