Meth, green, linctus, physeptone

Methadone linctus

Methadone is a synthetic opiate used as a strong painkiller and as a substitute for heroin in the treatment of heroin dependence.

Like heroin, it is a sedative drug that can produce feelings of relaxation and can reduce physical and psychological pain, but methadone doesn’t deliver the same degree of pleasurable effects as heroin.

Methadone is most commonly available as a green liquid or as tablets and occasionally as ampoules of liquid. Supplies may be diverted from medical stocks and become available on the street.


When a heroin user first begins treatment they are given a level of methadone (or other substitute drug) that is enough to minimise the withdrawal symptoms from the heroin.

The idea is that methadone will:

  • Suppress symptoms of opioid withdrawal
  • Decrease cravings for opioids and hence illicit opioid use
  • Change risky behaviour such as injecting and sharing needles
  • Stop the need to commit crimes to fund the heroin habit
  • Help patients stay in treatment

A large number of studies support methadone’s effectiveness at reducing opioid use (Research report from National Institute on Drug Abuse 2021).

More common side effects are:

  • constipation
  • nausea or vomiting
  • feeling sleepy, tired or dizzy, confused
  • headache
  • feeling cold and sweating more than usual
  • dry eyes, mouth and nose
  • Hallucinations
  • changes in mood

Methadone, as with all the stronger opioids, can itself become addictive.

It is very important that methadone should be kept out of the reach of children. There have been fatalities from children drinking the liquid which they may find particularly attractive due to its vivid green colour.

The law

Methadone is controlled as a Class A drug under the Misuse of Drugs Act. Unauthorised possession can lead to up to seven years in jail. Supply can lead to life imprisonment and/or an unlimited fine.

See also buprenorphine which is another substitute drug that may be prescribed to help people come off heroin.

Updated May 2022