Exploration of the benefits of methadone treatment for dual users of heroin and crack who inject or have previously injected drugs: preliminary findings

First published: 10 May 2019 | Last updated: 20 May 2019


To explore the physical health and heroin use of IV drug users in methadone treatment by comparing high (≥70 mg daily) vs. low (<70 mg daily) dose, and route of administration of crack (none/smoked/intravenous).

Design: Retrospective study

Setting: Two community drug services in London, UK

Participants: Current or previous intravenous users of heroin in methadone treatment (n=258 for part 1; n=20, recruitment ongoing for part 2).

Measurements: Logistic regression (part 1); In-depth interviews covering drug use, injecting and treatment history, physical health (part 2).


Part 1

The duration of drug use, daily drinking, intravenous crack use and high dose of methadone correlated positively with poor physical health (OR=1.06, 95% CI: 1.03–1.09; OR=2.18, 95% CI: 1.11–4.28; OR=4.79, 95% CI: 2.11–10.89; OR=1.82, 95% CI: 1.06–3.15). Compared to low dose, more high-dose heroin-only users stopped using heroin (71% vs 35%), but this was reversed for dual users (17.2% vs 23.4%). 71% of intravenous users of crack on high dose were still injecting heroin compared to 57% on low dose.

Part 2

Compared to low dose, participants on high dose experienced more severe health problems, continued intravenous drug use for longer (14 ±-7.4 years vs. 9 ± 6.8 years) and were more likely to using high-risk injection sites (groin, neck) (71% vs 38%). Their most frequent reason for stopping IV use was due to difficulty finding veins on a high-risk site, or a related severe health complication, whereas many participants on low dose switched to smoking when not able to find veins at lower-risk sites.


These preliminary results suggest that the benefits of high doses of methadone might be limited for dual users of heroin and crack, and the use of both drugs is interconnected.


Jenny Corless, Southwark Drug Services, London, UK Mary Bell MacLeod, Camden and Islington NHS Foundation Trust, London, UK Lynne Dawkins, London South Bank University, London, UK

Conflicts of interest:

No conflict of interest

Dr Felicia Heidebrecht