14 May 2019 

New research finds heating drug use equipment linked to decreased HIV risk

  • An outbreak of HIV occurred among people who inject drugs in London, Ontario in 2016
  • Researchers found HIV was transmitted through sharing of drug use equipment
  • Heating drug use equipment was found to reduce the risk of infection

Injecting and sharing equipment for opioids is associated with many harms, including an increased risk for serious bacterial, fungal and viral infections. These include HIV and viruses that attack the liver such as hepatitis.

Approaches to improve the health of people who inject street drugs (PWID) include the provision of many services, particularly opioid substitution therapy and the distribution of sterile syringes, needles and equipment

In 2016, authorities in London, Ontario, declared a public health emergency, as an epidemic of HIV had broken out among PWID. Scientists were initially puzzled by this resurgent epidemic, as London has one of the highest rates of distribution of sterile needles and syringes in Canada  and one of the highest rates for the prescription of opioid substitution therapy in Ontario.

To find some answers, scientists at Western University in London began several studies. They conducted interviews with more than 100 PWID to find out more about injecting behaviour and performed extensive analyses of all of the equipment used for injecting in this population. They found that residue from hydromorphone controlled-release (HMC; sold as Hydromorph Contin) in equipment used by PWID helped HIV to persist and maintained its infectivity. Furthermore, well-designed and meticulous laboratory techniques found that brief heating to a boil of drug preparation equipment with a cigarette lighter appears to render HIV in such equipment non-infectious. Subsequently, the London scientists collaborated with local public health and harm reduction networks to educate PWID about the importance of heating such equipment prior to using.

Since the release of the information by scientists at Western University, the Ontario Harm Reduction Distribution Program and the Ontario Harm Reduction Network have issued key messages for people who inject drugs (reproduced at the end of this article).

In London, Ontario

Through their interviews, scientists in London found that the substance preferentially used by PWIDs was hydromorphone controlled-release (sold as Hydromorph Contin in Canada and by other brand names—Palladone SR and Junista—in other countries). The scientists found that “prescription rates of HMC capsules were unusually high in London compared to other regions in Ontario, which may indicate widespread availability of the drug for diversion and injection.”

Steps to injecting

The scientists noted that HMC does not easily dissolve in water, so “preparation of the drug for injecting requires numerous steps,” which they outlined as follows:

  • controlled-release beads must be removed from the capsule and crushed
  • the crushed beads are mixed with water in a cooker to create a slurry (a semi-liquid mixture)
  • the preparation is then drawn into a syringe through a cotton filter to remove visible particles

The scientists stated: “The filters, cookers and water are referred to as injection drug preparation equipment (IDPE). The high cost and large dose of hydromorphone in the controlled-release formulation, as well as the need to dissolve the capsule in a large volume of water, increases the likelihood that the IDPE will be shared between people. The large volume of the slurry can require multiple injections and therefore PWID are tempted to divide the injections among several people, while sharing costs. In addition, PWID report that large amounts of undissolved drug are retained in the filter and cooker after the first use, thereby encouraging the reuse and sharing of used IDPE.”

Reusing IDPE

The scientists noted that “reuse of IDPE is achieved by adding water to the previously used cooker containing the residual drug, placing a needle into the previously used filter and [pulling up] the residual drug [which they called “the wash”] into the needle. Multiple PWID may participate in serial washes, whereby the same filter/cooker/drug complex and needle/syringe are reused each time, with some PWID performing and sharing as many as seven washes from a single preparation of HMC. While PWID reuse and share the same IDPE, they often reuse their own, but do not share, needles/syringes.”

Laboratory findings

After detailed laboratory experiments with typical equipment used for IDPE, the Western University scientists stated that they found the following:

  • “45% of the total hydromorphone in an HMC capsule remained in IDPE after its initial use and was therefore available for use in subsequent washes.”
  • “Heating the solution of hydromorphone did not significantly change the amount of hydromorphone in the solution within the syringe or the amount recovered from IDPE. [The liquid] in the cooker reached its boiling point in less than 10 seconds when using a cigarette lighter.”

HIV persistence

The scientists stated that they conducted experiments that simulated “drug preparation habits” (in a lab setting) and they added HIV to the IDPE. The scientists reported that “when preparing the HMC for injection, infectious HIV was found at the following time points”:

  • five minutes
  • one hour
  • four hours

Additional experiments suggested that infectious HIV would have persisted on IDPE used with HMC despite “six serial washes,” according to the scientists.

(When scientists repeated the experiments using immediate-release hydromorphone, there was significantly less HIV on IDPE, however, it was still infectious.)

The scientists stated that ingredients in HMC (including time-release microcrystalline and other formulations of cellulose) “apparently allow the filter to retain HIV when impregnated withHMC.”

Further experiments found that the cotton filters (that were reused by PWID) can retain infectious HIV for up to 72 hours after initial contamination. Furthermore, when HMC was added to the filters, higher levels of HIV remained on the filters.

Money and residual drugs

The data from the Western University research found that 45% of the contents of an HMC capsule remain in the IDPE after initial use. The scientists stated that this relatively high level of residual HMC “incentivizes the behaviour of frequent IDPE reuse to access the remaining HMC.” The current street value of a capsule of HMC is about $60 Canadian (or $45 US; €40).

The scientists added that due to this relatively high street value, “disposal of the remaining drug in the IDPE is very uncommon [with HMC]. This leads to IDPE being commonly shared and sold among PWID, despite nearly absent sharing of needles and syringes. In contrast, the low quantity of residual immediate-release hydromorphone on the IDPE, due to the lower dose and higher solubility of immediate-release opioids, provided less incentive to reuse IDPE [when immediate-release hydromorphone is used]. These findings likely explain the common behaviour of multiple repeated uses of IDPE and the sharing of washes with the HMC but not immediate-release formulations of hydromorphone.”

Routes of infection

The scientists stated: “As PWID commonly reinsert their own used needle into the IDPE from multiple washes using a single syringe/needle, this can lead to the IDPE becoming contaminated with HIV. When a second PWID inserts their needle into the same filter, they can become infected via injecting.” As most PWID are careful and do not share syringes/needles, the scientists stated that “they commonly reuse their own needles/syringes as they are unaware that it may [transfer HIV] to the IDPE and thus risk the [spread of HIV] by this mechanism.”

Taken altogether, the findings by the Western University scientists suggest that the spread of HIV to “the second PWID’s injection equipment would be very feasible.”

Persistence of HIV

Based on their findings, the scientists suggested that non-medicinal ingredients in the controlled-release formulation of hydromorphone, such as different formulations of cellulose, likely allow HIV to persist in IDPE. These ingredients are not in the immediate-release formulation. The scientists have recommended that manufacturers of opioids “that may be diverted for injection should consider seeking alternative [non-medicinal ingredients] given the potential increased risk of blood-borne pathogen transmission.”

“Cooking the wash”

The scientists found that heating IDPE until boiling, which is commonly called “cooking the wash,” destroyed HIV. They stated that “this process is easily performed with boiling of the HMC solution occurring in less than 10 seconds when using a cigarette lighter.” A separate study by other researchers has found that boiling also significantly reduced the amount of bacteria that contaminate IDPE. Further studies are needed to assess the impact of boiling on other germs that can contaminate IDPE, such as fungi.

Based on the research by the London scientists, a public education initiative called “Cook Your Wash” was launched in the London region in June 2017. According to the scientists, the initiative encouraged PWID to “heat their IDPE with a cigarette lighter until bubbling for each wash prior to [injecting]” This initiative provided additional harm reduction messages in the context of a community with high uptake of harm reduction services that also promoted the use of new needles, syringes and equipment for every injection.

The scientists reported that “preliminary data showed a decrease in new HIV diagnoses in the second half of 2017, such that the HIV incidence was no longer significantly above the provincial rate. Anecdotal evidence suggests widespread uptake of the recommendation by PWID but further studies are ongoing to document the changes in behaviour associated with the campaign.” They added that as injecting opioids “continues to increase, the implementation of harm reduction strategies that target IDPE sharing as a mechanism of HIV transmission will become increasingly important."

Ontario harm reduction group’s advice for people who inject drugs

The research by the Western scientists focused on HIV. However, other germs can be spread by sharing equipment for substance use. Therefore, the Ontario Harm Reduction Distribution Program and the Ontario Harm Reduction Network have issued a helpful note for people who inject drugs:

  • It is best to use new/sterile equipment every time you prepare and use drugs; sharing equipment, or your wash, increases the chance of infections.
  • Cook your drugs (including a wash) before every injection: heat the solution until it bubbles, then let it cool down before injecting.

Harm reduction experts explain that all of these steps have benefits. For instance, boiling reduces viral, bacterial (and possibly fungal) infection of equipment, while cooking helps drugs dissolve (and dissolved drugs are easier on people’s veins). Cooking and cooling the wash and drugs makes wax used on pills rise to the surface and makes this wax easier to remove. A cool solution will also be easier on your veins.

Furthermore, the experts  added that a combination of factors contribute to potential spread of viral, bacterial and fungal infections. You can reduce your risk for these infections by doing the following:

  • wash your hands prior to preparing your drugs
  • clean your skin where you will inject, just before you inject
  • prepare and use drugs in more hygienic environments (use overdose prevention and drug consumption sites if you have access)

Talk to your harm reduction workers about what safer drug use supplies you can access and ways to use drugs more safely.


Ontario Harm Reduction Distribution Program & Ontario Harm Reduction Network. Note to Harm Reduction Programs and Staff Regarding Recent HIV Research and ‘Cook Your Wash’. 2019.

—Sean R. Hosein


  1. Ball L, Venner C, Tirona RG, et al. Heating injection drug preparation equipment used for opioid injection may reduce HIV transmission associated with sharing equipment. JAIDS. 2019; in press.
  2. Ball LJ, Puka K, Speechley M, et al. Sharing of injection drug preparation equipment is associated with HIV infection: A cross sectional study. JAIDS. 2019; in press.
  3. Fischer B, Pang M, Tyndall M. The opioid death crisis in Canada: Crucial lessons for public health. Lancet Public Health. 2019 Feb;4(2):e81-e82.
  4. Lloyd-Smith E, Hull MW, Tyndall MW, et al. Community-associated methicillin-resistant Staphylococcus aureus is prevalent in wounds of community-based injection drug users. Epidemiology and Infection. 2010 May;138(5):713-20.
  5. Stenstrom R, Grafstein E, Romney M, et al. Prevalence of and risk factors for methicillin-resistant Staphylococcus aureus skin and soft tissue infection in a Canadian emergency department. Canadian Journal of Emergency Medical Care. 2009 Sep;11(5):430-8.
  6. Barter DM, Johnston HL, Williams SR, et al. Candida bloodstream infections among persons who inject drugs - Denver Metropolitan Area, Colorado, 2017-2018. Morbidity and Mortality Week Report. 2019 Mar 29;68(12):285-288.
  7. Mahale P, Aka PV, Chen X, et al. Hepatitis D viremia among injection drug users in San Francisco. Journal of Infectious Diseases. 2018 May 25;217(12):1902-1906.
  8. Young J, Rossi C, Gill J, et al. Risk factors for hepatitis C virus reinfection after sustained virologic response in patients coinfected with HIV. Clinical Infectious Diseases. 2017 May 1;64(9):1154-1162.
  9. Foster M, Ramachandran S, Myatt K, et al. Hepatitis A virus outbreaks associated with drug use and homelessness - California, Kentucky, Michigan, and Utah, 2017. Morbidity and Mortality Weekly Report. 2018 Nov 2;67(43):1208-1210.