It is easy to buy medicines, including addictive ones, via internet but consumers should be aware there are often no quality controls on what they are getting, the Dutch consumers association Consumentenbond said on Tuesday.

The organisation ordered 20 different drugs – sleeping pills, antibiotics, medicine for cancer treatment and tranquilisers – from 12 online suppliers in the Netherlands and abroad without a prescription.

In total, 16 orders were met by websites based in the Netherlands, Britain, Switzerland, India and Singapore.

An analysis of the drugs by the public health institute RIVM found that almost all had more or less active ingredients than given on the packaging. While there can be small variations in ‘official medicines’ the antibiotics ordered had up to 625 mg of the active ingredient rather than 500 mg, the research found.

These websites are getting round Dutch law by using foreign doctors and pharmacies, Consumentenbond director Olof King said.

‘One of our mystery shoppers filled in the form of medical questions and was delivered antibiotics by a British pharmacy on the basis of a prescription from a doctor in Romania.’

The organisation wants the health minister to give better warnings about the risks attached to buying medicine online.