Britain banned several drugs known as "legal highs" Wednesday amid mounting public concern about their health risks.
Substances including chemical solvent GBL, often used by nightclub-goers, and BZP, a stimulant similar to amphetamine, are now illegal, as are herbal smoking products containing man-made chemicals such as "Spice".
Long-standing concerns about the health risks of the drugs, particularly when taken with alcohol, hit the headlines in April after 21-year-old medical student Hester Stewart died after taking GBL.
Her mother, Maryon, campaigned nationally for a ban.
"We are cracking down on so called 'legal highs' which are an emerging threat, particularly to young people," said Home Secretary Alan Johnson.
"That is why we are making a range of these substances illegal from today with ground-breaking legislation which will also ban their related compounds."
The ban has also been extended to 15 anabolic steroids, which are often used by sports people, Johnson said.