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How pure are street drugs?

There is no proper quality control over illegal drugs.


It is often difficult to know whether a powder, pill, resin, herb or liquid is a particular drug. Even if you think it is a particular drug you may have no idea how strong the dose is, whether it also contains another drug(s) or other substances to bulk it out. Illegal drugs may contain:

  • Impurities – substances present in the drug as a natural result of how it was made rather than deliberately added. For example, opiate alkaloids may be present in heroin from refining opium into heroin.
  • Adulterants – these are drugs that deliberately mimic or enhance the effects of the drug being offered. Examples are the way caffeine and/ or ephedrine are often found in amphetamine or ecstasy.
  • Dilutents – these are mainly sugars such as glucose, lactose and mannitol. These are added to bulk out the deal and assist the process of dilution of the drug for injection.

It can obviously be dangerous to take something that you are not sure about. A strong dose may leave someone disorientated and they may panic, freak out and be more likely to be involved in accidents. Similarly taking what you think is one type of drug and finding that it is another, with possibly very different effects, can be disturbing. While impurities and dilutents can, in themselves, be dangerous to consume the likelihood of this happening has often been exaggerated. While rumours circulate about drugs cut with rat poison, strychnine and brick dust such contamination is very rare. It is not in the dealer’s interest to have customers dropping dead from deliberately contaminated drugs. In contrast people will return to get drugs from dealers who offer good quality substances.

Purity of street drugs and what they contain varies between different places and can also change within a matter of days. Below is only a rough guide to what we know about the purity of different drugs. This is a guide to national patterns and should not be relied on to determine the content of substances circulating in your area– onlyanalysis of local samples can do that, and mistaken assumptions could be risky.


The most impure illegal drug. Purity may be up to 10 per cent but is more commonly less than 5 per cent with some samples as low as 1 per cent purity. Amphetamine is often cut with sugars, caffeine and/or ephedrine and sometimes with paracetamol, Vitamin C, chalk and talcum powder.


Purity can vary from 20-90 per cent with an average around 50-60 per cent. The rest is usually made up of sugars such as glucose, lactose and/ or mannitol.

Crack cocaine

Usually 70-75 per cent pure cocaine freebase and up to 100 per cent pure in some samples.


The amount of ecstasy (MDMA) in one tablet may vary. Some tablets sold as ecstasy may contain no MDMA and be other drugs. Many ecstasy tablets also contain other drugs – ketamine, amphetamine, caffeine, ephedrine, and the tranquilliser, flunitrazepam, have all be found. Some tablets also contain other ecstasy type drugs such as MDA or MDEA. The average amount of MDMA in a genuine tablet is 70–80 milligrams, but occasionally much larger amounts may be present.


Usually 30-80 per cent pure, averaging at 45-50 per cent pure. The rest is usually paracetamol, other opiate alkaloids, sugars and sometimes methaqualone or diazepam (valium). Varying purity has often been connected to fatal overdose through injecting heroin when people take a higher purity dose than they are used to. LSD Now rarely seen by police or customs. Usually sold as small paper squares, cut from larger sheets which have been soaked in the drug. Most squares do have LSD but fakes with no LSD at all can be sold. The dosage of LSD on one square can vary a lot.

Anabolic steroids

Most steroids bought in gymnasia are either fakes or counterfeits. Fakes contain little or no steroid (though sometimes they do contain drugs other than steroid) or a different steroid from that cited on the label. Counterfeits are illicitly manufactured products sold as the genuine pharmaceutical drug.

How can people know what they are really buying? The only sure way of knowing is to have a drug properly tested. The police and some private laboratories can test drugs. In Amsterdam some clubs and drug agencies offer an ecstasy testing service. People can then check what a drug is before taking it and word can be put out if any particularly dangerous tablets are circulating. Some people would like to see a similar service available in this country but our drug laws and policing policies limit the likelihood of it happening.

Updated January 2005

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