Jeremy Laurance: Not everything is safe just because it's not illegal

If it's legal it must be safe. This is the misconception that is leading many drug users into danger. Like the fashion for organic food, people are being lulled into a false sense of security.

Tweaking the chemical formula of a drug like ketamine does not make it safe. The answer to the question "Is it safe?" can only ever be: "It depends."

Some legal highs may be safer than their "natural" alternatives. A good example is nicotine, the active ingredient in cigarettes, which is a great deal safer when delivered in pure form than when taken with tobacco.

The same cannot be said for most. The recommendation from the Advisory Council on the Misuse of Drugs that all substances that are chemically or pharmacologically similar to controlled drugs should be automatically banned to enable the authorities to keep up with the ever-changing chemistry of new drugs is surely right.

Novel substances such as mephedrone and MXE are very difficult to control and make a mockery of the law. The Misuse of Drugs Act needs updating.

But it is important not to overreact. New drugs may be appearing with growing frequency but there is no evidence they are gaining a wide market.

Mephedrone, synthetic cannabinoids and now, possibly, MXE are the exceptions. This is not a trend yet out of control.