Many drugs sold as ‘legal highs’ online do not contain the ingredients advertised, a new study finds. A British chemist purchased products sold as research chemicals, bath salts and plant food that were clearly marketed toward recreational drug users. Most didn’t contain the supposed active ingredient that was advertised, he reported in the journal Drug Testing and Analysis.

The Los Angeles Times reports that Mark Baron tested seven product samples and found that six did not contain the advertised active ingredient. He also found that five contained two controlled substances that are illegal to sell over the Internet: benzylpiperazine and trifluoromethylphenylpiperazine, mixed with caffeine.

“It is clear that consumers are buying products that they think contain specific substances, but that in reality the labels are unreliable indicators of the actual contents,” Dr. Baron said in a journal press release. “The product name cannot be used as an indication of what it contains as there is variation in the content of the same product name between different Internet sites.”