London: Buying medicine online is full with risks as they could contain prohibited substances, a researcher says.

"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," says Mark Baron, from the School of Natural and Applied Sciences, University of Lincoln.

Baron says that buyers need to be aware that they have no idea what they will be taking and that some of the products could contain illegal substances, reports the journal Drug Testing and Analysis.

Recently, there has been an explosion in the number of substances deemed 'legal highs' that can be found readily available on the internet, according to a Lincoln statement.

Baron bought a range of tablets from different websites to see what each contained.

Purchasing them was easy numerous online legal-high retailers market a broad variety of products advertised as research chemicals, bath salts, or plant food, although clearly marketed towards the recreational drug user.

"No guidelines exist as to what is sold and in what purity and consumers are led to believe that purchased goods are entirely legal," says Baron.

Six out of seven products he bought did not contain the advertised active ingredient. More disturbingly, five samples contained controlled substances combined with caffeine.