Speed is the most popular name for amphetamine, which is a chemical compound that acts as a stimulant. Its chemical structure closely resembles the body's own chemical transmitter norepinephrine, which plays an important role in the fight-or-flight response to stress and excitement.

There are three main pharmaceutical classes of amphetamine (the common brand names are in brackets): laevo or dl-amphetamine (Benzedrine), dextroamphetamine (Dexedrine) and methylamphetamine (Methedrine). The latter is also known as crystal meth and, weight-for-weight, is the most potent of the three.

The most common street speed is amphetamine sulphate, which comes as a grey, dirty-white or pinkish powder and is snorted, rubbed on the gums, dissolved in liquid for injection or drinking, or swallowed in pill form. A 'speedbomb' consists of speed twisted up in a cigarette paper, which is then swallowed.

It's the most impure illegal drug available in the UK - it can be heavily cut with paracetamol, baby milk powder, talcum or other substances, so it's unlikely you'll know exactly what you're taking. Base speed - which is pinkish-grey and feels like putty - is purer.

What effects do amphetamines have?

• Amphetamine is a stimulant. It quickens the heartbeat and speeds up breathing.
• Users become more lively, confident and outgoing.
• A tense jaw and teeth grinding are also common and known as gurning.
• Speed can dramatically reduce a person's appetite, but doesn't meet any of the body's nutritional needs.

What are the risks of taking amphetamines?

• Some users become tense and anxious while on amphetamines.
• The comedown can last for a couple of days, leaving users feeling tired, depressed, irritable and physically uncomfortable.
• In the short term, memory and concentration can be affected.
• Tolerance for amphetamines can build quickly, so bigger doses are required for the same sort of hit.
• Heavy abuse over long periods can also place a serious strain on the heart and has been linked to mental illnesses such as psychosis and paranoia.
• Heavy use can put a strain on the immune system, making users more susceptible everyday illnesses like colds and flu.
• Amphetamine users have died from overdose.

The law and amphetamines:

Amphetamines are Class B drugs, but carry Class A penalties if prepared for injection. Crystal meth is a Class A drug.

Amphetamines are also known as:

Speed, meth, base, glass, uppers, whizz, billy whizz, sulphate or sulph, wake-up and crank paste.

If you're planning on taking amphetamines:

• The greatest danger to your health is from mixing amphetamines with cocaine or ecstasy. The first is an unlikely combination because they have such similar effects. This pairing brings a danger of increased toxicity and strain on the heart;
• Mixing with ecstasy puts extra strain on the heart and you will be at risk of over-heating;
• It is possible to overdose on amphetamines, which can lead to permanent damage or death;
• If you are using amphetamines over long periods of time you are advised to take multi- vitamin and calcium supplements, as well as keeping a check on your body weight;
• Avoid injecting speed. This can damage your body and sharing needles can pass on diseases such as HIV;
• If you have schizophrenic tendencies there are real dangers that even the mildest use of speed could push you over the edge.

Updated: 16/10/2009