Also known as methamphetamine, tina, crystal meths, krank, tweak, ice, yaba

Methamphetamine was originally manufactured by the Nazis to help keep their troops awake for days at a time. It has been popular with gay men on the West Coast of North America for the last decade, and, as Yaba, is now more popular than heroin in Thailand. As the use of crystal meth has moved across the US to the East Coast, there are concerns that it is now being targeted at Europe and the UK. There have been recent reports that crystal meth is being used by UK gay men, mainly at private parties. At the moment it is unclear how easily available crystal meth is and how widely it is being used.

A derivative of synthetic amphetamines, it can be manufactured far more quickly and easily than traditional forms of amphetamine. The main ingredients, which include salt, household cleaning products, distilled cold medicines and lithium from camera batteries can be bought legally and the drug can be made at home. However, it can come in pill form, as powder to be snorted or injected, or in its crystal form 'ice', smoked in a pipe. In the UK, reports suggest that crystal meth is available in a number of different forms including paste, crystals and possibly suspended as a solution.

Crystal meth brings on a feeling of exhilaration and a sharpening of focus, which leads to intense feelings of sexual power which can result in marathon sex for hours on end. Several recent studies have linked the use of crystal meth with increased sexual risk-taking, especially when combined with Viagra (see also Viagra below). It has been reported in the States that crystal meth has been a factor in almost half of new HIV infections amongst gay men.

Smoking crystal meth results in body temperature rises and rapid cardiac and respiratory rates developing as the blood pressure increases.

The effects and dependence potential of crystal meth are similar to that of amphetamine misuse, although since it is more potent, the dangers involved are greater with an increased chance of overdose. Overuse can bring on paranoia, short term memory loss, wild rages and mood swings as well as damage to the immune system. Although it does not appear to be physically addictive, psychological dependence for the drug does occur.

Overdosing can lead to severe convulsions followed by circulatory and respiratory collapse, coma and death. Some people have died after taking small doses.

In 2005 (Chang) US scientists used magnetic resonance imaging to determine the level of neurotransmitters in the brain which are markers of healthy neurones. They found lower levels of the neurotransmitter Nacetylaspartate in the basal ganglia, cells which control the co-ordination of movement. These cells are also the ones most frequently damaged by HIV itself.

The investigators speculate that the additive effect of HIV and methamphetamine may be related to the drug’s effect on the neurotransmitter dopamine. Methamphetamine causes the release of massive amounts of dopamine from the ends of neurones, notably in the basal ganglia. This release of dopamine often causes the ends of the neurones to shrivel and eventually die back. The researchers hypothesise that this release of dopamine can also stimulate HIV replication and worsen the damage caused by the drug.

Crystal meth has been widely and at times hysterically blamed for rising levels of unprotected sex and HIV infection in gay men, especially in US cities.

At the 12^th Retrovirus Conference in February 2005, Grant Colfax of the San Francisco Department of Public Health said that poppers, cocaine and crystal meth were the biggest single contributory factor to continued HIV transmission between gay men.

Colfax told the conference that using crystal raised the risk of unsafe sex two to three times, and the risk of HIV infection by 60 percent.

Receptive unprotected anal sex raised the risk of infection by nearly 300 percent. But because taking drugs during sex was more common than getting penetrated without condoms, the "attributable fraction" of HIV cases due to drug use (that is, the contribution drug use made to HIV transmission) was 29 per cent, beating unprotected receptive anal sex by one per cent.

On the surface, Colfax admitted, it was puzzling that using a drug was even more risky than directly indulging in the sexual behaviour most likely to transmit HIV.

But all sorts of factors could come together to make users of coke and crystal particularly vulnerable. Pain was dulled, so injuries for HIV to pass through could be more common. Other drug users were already more likely to be HIV-positive, and also less likely to remember to take HIV medication, and therefore more infectious. And users might simply not be able to remember what they'd done.

In addition, he said, drugs suppressed the immune system, and poppers caused increased blood flow to the anal region. All of these factors made transmission more likely.

Colfax said that a number of studies have shown that drug use in gay men was two to three times higher than in straight men of comparable age, and two to three times as high again in HIV-positive gay men.

Interestingly, and in contrast with findings about other HIV risks, young white gay men were particularly at risk. In one study of young gay men under 25 in seven US cities, half of all white men said they had used crystal, four in ten cocaine and one in eight crack. In contrast, only one in six young black men had used crystal meth, one in eight coke and one in 20 crack. "So much for urban stereotypes," commented Colfax.

He then looked at what could be done to help gay men stop using. One study of group support had shown no effect, but it may simply have been too intense. (It was a three-times-weekly Narcotics Anonymous-type meeting.) Behavioural therapy produced modest reductions. More typical one-to-one counselling reduced the number of unsafe-sex episodes by three-quarters, but didn't stop men using drugs. (It may have just helped them feel good enough about themselves to use condoms.)

One of the most promising approaches, he said, was a New York incentive scheme that gave users substantial rewards in the form of department store vouchers if they produced consecutive urine tests free of drugs. But this was obviously only appropriate for the 25 percent or so of crystal and coke users who are dependent, rather than recreational weekend users.

He also looked at substitution therapy, or giving another drug to stop drug use - nicotine patches for smokers, Antabuse for alcoholics, methadone for heroin addicts.

No substitute drug had worked so far for "uppers" like coke or crystal, he said, but there was a trial in heterosexuals with problem crystal use of a drug called bupropion. This raises the levels of dopamine, the brain chemical over-stimulated by coke and meth. Dopamine crashes during comedown, tempting users to have another tweak. Results were yet to come out and, as with methadone, some people feared substitution therapy would have no influence on sexual-risk behaviour, or even increase it.

Finally, Colfax said, although he didn't have time to comment, there was probably no substitute for a strong community response, and he praised community campaigns to make crystal less ‘sexy’.

For more on interactions between crystal meth and HIV drugs, see drug interactions below.