Ministers say that the components of herbal highs - whose use was highlighted by the Independent on Sunday earlier this year - have been linked to at least 15 deaths in the US in the last year.
The substances, which are mostly in pill form, and sold under names like Aztec Black, Fantasy and Skull Cap, are available through mail order, in clubs and at specialist shops. Ads contain promises such as "robs your mind with a concoction of psychedelic sensations", or "giggles, time distortion, perceptual change and brighter colours".
The Government is worried about the effects of ingredients such as ephedra, linked to at least 15 recent deaths in the US, khat, which can cause psychosis, and yohimbe, potentially harmful when used in conjunction with drugs found in cold remedies.
The tough stance is in line with the Government's decision to create a "drugs tsar" to co-ordinate the war against narcotics. One of the likely candidates, Ian Oliver, Chief Constable of Grampian Police, yesterday called for greater co-ordination of anti-drug activity. He told the BBC: "We have all sorts of people operating in different directions and achieving very little; wasted effort, wasted money and wasted resources."
The Government says the Medicines Control Agency had contacted "herbal high" traders and obtained undertakings that the products would not be sold, but undercover officers had reported a brisk on-going trade.
Alan Milburn, Minister of State at the Department of Health, will this week say that, under the Medicines Act of 1968, sale of herbal highs without a licence will be treated as an offence. Those responsible could face two years in prison for each item sold and unlimited fines.
Dr Hermans, a shop in Camden, north London, is an Aladdin's cave of clubbing gear, records, pipes and bongs. Between the nose-piercing booth and the "brain-machine" room is a counter where "herbal high" products are sold.
The menu, on a board by the counter, includes Calamus ("Bend your mind and distort your vision"), Mind Bandits ("Lively freaky psychedelic pills") and Yellow Submarines ("Dive into an ocean of colour"). "Are you sorted for herbal Es and whizz?" enquires a notice on the wall.
Owner Charly Hughes snorted at the prospect that his products might require a licence. "Bloody ridiculous," he said. "We do a lot of good in stopping people taking illegal drugs. There are risks in this stuff, but there are risks in everything." He said he would continue to sell abroad if there was a crackdown here. "I don't believe they've thought through the consequences. We have a big-time drug culture in Britain but the political message is all over the place."