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Research report

What are the risk factors for soft tissue abscess development among injecting drug users?

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Drug users who inject are at high risk of developing soft tissue abscesses. Nurses need to incorporate safer injecting advice into their interactions with clients



Stephanie Maloney, BSc, RGN, is staff nurse; Eammon Keenan,MBBCh, BAO, MRCPsych, is consultant psychiatrist and clinical director; Noreen Geoghegan, BSc, Higher Dip, RM, RGN, is assistant director of nursing; all at addiction services, Health Service Executive Dublin Mid-Leinster.


Maloney S et al (2010) What are the risk factors for soft tissue abscess development among injecting drug users? Nursing Times; 106: 23, early online publication.

Background Much research has been conducted on the risk taking behaviour of injecting drug users. Cutaneous or subcutaneous skin and soft tissue abscesses are common complications of intravenous drug use.

Aim To identify the risk factors to which injecting drug users expose themselves to improve initial assessment.

Method A convenience sampling method was used, and structured interviews were carried out with 70 injecting drug users attending a methadone treatment setting in Dublin.

Results and discussion Forty eight (69%) of participants have had an abscess at some stage. Poor levels of skin cleansing were identified as a main cause, and 80% admitted to sharing injecting equipment.

Conclusion Healthcare professionals need to develop better strategies for delivering safety messages to clients about safer injecting behaviour.

Keywords: Risk factor, Soft tissue abscesses, Injecting drug use

  • This article has been double-blind peer reviewed



Practice points

  • Skin and soft tissue abscesses are serious and expensive complications of intravenous drug use.
  • Nurses need to be aware of clients’ patterns of injecting drug use and take a more proactive approach to giving safer injecting advice
  • Clients need to be given full education on the importance of using alcohol wipes before injecting, especially as many inject in public places, where no cleansing facilities are available.
  • Assessing skin integrity allows nurses to ascertain the presence of any abscesses or tissue damage as a consequence of injecting.



A great deal of research has been conducted on the risk taking behaviour of injecting drug users, although it has focused mainly on the risk of transmission of bloodborne disease such as HIV, hepatitis B and C, and the associated risk behaviour (Grogan et al, 2005; Smyth et al, 1999).

However, it has long been recognised that injecting drugs carries many other health risks, and the conditions under which illicit drugs are usually injected predispose people to many infections (Drake et al, 2001).

Cutaneous or subcutaneous skin and soft tissue abscesses are common complications of intravenous drug use. Our service perceives these as a serious and costly problem. One effect is greatly increased nursing workload within the service.

A community based study in San Francisco estimated that one in three injecting drug users has an active abscess at any given time (Binswanger et al, 2000).

A study in Vancouver on prevalence and correlation of abscesses among a cohort of injecting drug users indicated that injecting related infections, such as abscesses and cellulitis, account for the majority of emergency room visits and acute hospital admissions among this group (Smith et al, 2005).

Developing abscesses

Why some injectors develop abscesses and others do not is not well understood. While abscesses form readily but not consistently, it is unclear what mechanisms or opportunistic factors contribute directly to the problem. Infectious substances may be involved at any time in the harvest, manufacture or preparation of the drug for injecting (Murphy et al, 2001).

Cleansing the skin before injecting is recommended as a method of reducing if not eliminating the frequency of serious infection. The environment around us, including the air and surfaces, contain small particles and potentially infectious microorganisms at all times.

Drug users may cleanse the skin with alcohol swabs before injecting. Cleansing on withdrawing the needle is also not uncommon, but equally injecting without any skin cleansing at all does occur (Finnie and Nicolson, 2002). 

Many injecting drug users inject without even washing their hands. One study of street based injectors found that nearly 98% had injected in a public place, including cars, public toilets and trains. Many injectors had no access to running water or clean surfaces on which to prepare their drugs for injection (Rhodes et al, 2006).

Binswanger et al (2000) identified the use of dirty needles and skin cleansing with alcohol as two potentially modifiable risk factors for causing and preventing an abscess respectively.

Injection sites and technique vary. As the veins of the hands and arms become thrombosed and affected by abscesses, drug users begin to use the veins of the legs and feet. When they initially begin injecting, they use visible veins in the arms, then legs, before moving to any other part of the body where a vein can be identified (Finnie and Nicolson, 2002).

Long term injecting drug use can result in sclerosis and thrombosis of most superficial veins. Scars from abscesses are weak areas of skin and these areas may, in time, develop into ulcers. If venous access is no longer possible, users may resort to injecting subcutaneously or intramuscularly (skin popping) which has been shown to have a direct link to the development of abscesses (Binswanger et al, 2000).

Injecting drug users usually skin pop because they are unable to gain access to a vein. Several studies have noted that skin popping is associated with a higher risk of acquiring an abscess than through IV use (Finnie and Nicolson, 2002; Binswanger et al, 2000). 

Type of drug

Polydrug use is well established in any society in which a variety of prescribed or illicit drugs are available. Drug users can select from a range of drugs to supplement a reduced supply, or to complement the effects of a preferred drug.

Some studies in Ireland and Australia have reported that 77%-97% of respondents inject heroin as their main drug of choice (Day et al, 2005; Smyth et al, 2005).

After heroin, cocaine is the most common drug of choice for injecting. Drug trends vary constantly. In recent times, cocaine has dropped in price dramatically, leading to a 300 fold and 400 fold increase in those seeking treatment for cocaine use as a primary and secondary problem respectively (National Advisory Committee on Drugs, 2003). Because of cocaine’s short duration of effect and its local anaesthetic and psychomotor stimulant properties, it is often injected more frequently and frenetically than other drugs (Van Beek et al, 2001).

Cocaine has a direct cytotoxic effect and acts as a powerful adrenergic agent, so its use results in vasoconstriction of local tissue. This can predispose those affected to serious infections. Several studies have reported links between frequent cocaine use and the development of an abscess (Rhodes et al, 2006; Van Beek et al, 2001; Binswanger et al, 2000).

Aim and method

This study aimed to identify the risk factors to which injecting drug users expose themselves that can lead to the development of soft tissue abscesses. It is hoped that the findings can be used by nursing staff and other disciplines to help with clients’ initial assessment for treatment.


Participants were recruited through one of the main methadone treatment centres in the Health Service Executive Dublin Mid-Leinster region. This site was chosen because the nursing staff working there reported high numbers of clients presenting with an abscess.

This centre is one of the first established in the Dublin region so therefore has an older cohort of injectors. As a result, this study may not reflect the wider injecting drug user population.


A convenience sampling method was used. During the period of data collection over 300 clients were attending the treatment centre, and we hoped to interview 80-100 of them. The only inclusion criterion was that they were currently injecting or had done so in the past.

Data collection and analysis

The appropriate institutional ethics committee approved the study in December 2006. All participants gave written consent and were given an information sheet about the study before taking part. Participants were guaranteed strict confidentiality and data was collected anonymously.

Seventy clients agreed to participate. In total, 88 were asked, eight had never injected, nine refused and one withdrew consent during the interview process. All data collected was used only for the purpose of this study.

A structured 10-15 minute interview guided by a questionnaire was carried out with all study participants. A pilot involving 10 clients was carried out to refine the data instrument, but these clients were not included in the final results. The lead author conducted all the interviews; data was collected over six days in January 2007.

The interviewer coded and inputted data into SPSS for Windows (version 14) for analysis.


The sample consisted of 70 injecting drug users, 42 men (60%) and 28 women (40%). Their mean age was 30.44 years, with a minimum age of 21 and a maximum of 53.

Participants were asked their age when they first injected, and the responses then banded into age groups for analysis (Table 1; percentages have been rounded to whole numbers). Twenty six (37%) started injecting at the age of 18 or under. Only six clients (9%) started injecting aged 29 or over. Nineteen (27%) said they were still injecting on the date the data was collected.

All participants were asked how long they had been on a methadone maintenance programme. Thirty four (49%) reported being on methadone treatment for more than five years, 28 (40%) reported being on it for 1-5 years and eight (11%) between one week and a year.

Incidence of abscesses

Participants were asked if they had ever had an abscess or abscesses related to injecting drug use. Twenty two (31%) reported never having had an abscess.

More than half (n=48/70, 69%) reported having an abscess or abscesses. Eleven (16%) of the overall total of 70 reported having one once, 19 (27%) had had one 2-4 times, 14 (20%) reported they had one 5-10 times, and four said they had had more than 10 abscesses. Twenty three (33%) reported having an abscess within the last year.

Drugs injected at the time of last abscess

The 48 participants who reported ever having an abscess were asked what drugs they were injecting most commonly at the time they developed their last abscess. The two main drugs of choice identified were heroin and cocaine (Tables 2 and 3).

Twenty six (37%) of participants reported injecting heroin on average 3-5 times a day, and 20 (29%) said they would have injected heroin 6-10 times daily. Thirteen (19%) reported using cocaine more than 10 times a day, while only one reported injecting heroin more than 10 times a day. Thirteen said they had never injected cocaine.

Only one participant reported injecting heroin and cocaine one after the other – a term known as “speedballing” – at the time they last developed an abscess.

Of the 48 asked about the last time they developed an abscess, 44 (92%) of these said they were either injecting heroin or cocaine most of the time. Seventeen (35%) said they were using cocaine most of the time, and 27 (56%) said they were injecting heroin most of the time.

Participants were asked about other drugs they were injecting the last time they developed an abscess. Seven (15%) said they were also injecting flurazepam most of the time when they developed their last abscess. This drug is not licensed by the Irish Medicines Board for injection. Some clients may have been prescribed it for oral consumption and some may have bought it illegally.

Route and sites of injecting

Sixty three (90%) clients reported using either the right or left antecubital fossa as the first site they injected into. Thirty eight (54%) reported having an abscess in their right or left antecubital fossa.

When participants were asked the last site they had injected into, 24 (34%) reported their groin as the last site, and these clients reported using this site most of the time. Thirty (43%) said they had injected into their groin at some time, and almost half of these (n=14/30, 47%) reported having an abscess at this site at some stage.

Skin popping

Forty six (66%) of the total have skin popped at some time. Those who reported having an abscess 2-4 times (n=19, 27%) also reported skin popping, while 14 (20%) who had an abscess 5-10 times also reported skin popping, with three of these stating they skin popped as a route of injecting most of the time.

Skin cleansing

Fifty six (80%) of the total said they cleaned the skin before they injected. Only nine (13%) said they always used alcohol wipes to clean the skin first, while 22 (31%) reported using alcohol wipes most of the time. Nine (13%) said that, on rare occasions if their skin was visibly dirty, they would use soap and water to clean the skin before injecting.

When participants were asked if they had ever injected in a public place, 31 (44%) had injected in a public toilet at some stage, 34 (49%) had injected on the street, 48 (69%) had injected in a car, 12 (17%) reported injecting on public transport, 42 (60%) had injected in a stranger’s house and 28 (40%) had injected in prison.

Over 75% of participants said they injected at home most of the time. Only three (4%) said they had never injected at home.

Sharing equipment

When asked if they had ever used their injecting equipment before or after someone else, 36 (51%) admitted to sharing needles, 41 (59%) admitted to sharing syringes, and 56 (80%) admitted to using the same spoon as someone else. Thirty nine (56%) admitted to using a filter before or after someone else, 43 (61%) reported using the same water for mixing their drugs, 34 (49%) used the same water to wash out works such as syringes, needles and other equipment such as spoons, and 55 (79%) shared their citric acid.

Fifty one (73%) said they had shared drugs either by someone else’s spoon or by taking it from each others’ syringes. This is known as front/back loading in batch preparation. Front/backloading involves the preparation of heroin in one syringe and subsequent transfer of half the contents to a different syringe (Table 4).

Participants were asked how often they used new equipment before they injected, defined as all products being in their original packaging. Only 15 (21%) said they used a new needle every time, 14 (20%) said they used a new syringe, only three (4%) said they used a new spoon or pot, 48 (69%) said they used a new filter, 45 (64%) said they used new water for mixing, and 51 (73%) said they used new water for flushing their works.

Fifty six (80%) reported being hepatitis C positive, and 43 (77%) of this group have had an abscess at some stage.


The study found that, in total, 69% of participants said they had had an abscess at some stage, secondary to IV drug use.

As a service we need to be aware of clients’ patterns of injecting drug use if we are to give appropriate advice at needle exchange programmes and during our daily interactions with clients.

Our service has made an extensive effort to reduce the spread of viral infection among drug users. However, limited teaching and advice is given on how best to avoid bacterial contamination when preparing and injecting drugs.

As discussed earlier, skin cleansing with alcohol before injection is thought to reduce the amount of bacterial contamination introduced into the bloodstream. While 80% of participants in this study said they cleaned their skin before injecting, only 13% said they always used alcohol wipes.

Such teaching efforts may be warranted to reduce abscesses among injecting drug users. Simple things such as handwashing facilities may be limited among many in this group, so the use of alcohol swabs should be strongly advised. Although all needle exchange programmes in the Dublin Mid-Leinster region provide alcohol swabs, it appears that the importance of using them before injecting may not be highlighted enough to clients.

A high percentage of participants admitted to injecting in a public place. Just over 92% said they had injected in public at some stage. This indicates that many are injecting without access to proper handwashing facilities, running water or clean work surfaces. Needle exchange facilities should therefore consider providing clients with cleansing wipes.

This study reflected previous findings that cocaine is injected more frequently because its effects have a short duration, as 13 of those who had used cocaine had on occasion injected it more than 10 times a day. When asked about the last time they developed an abscess, just over one third of participants said they were injecting cocaine most of the time when they developed their last abscess.

An alarmingly high number admitted to sharing equipment. Equally low numbers admitted to using new equipment, with only 21% stating they used a new needle each time they injected, although a high percentage (69%) said they used a new filter. The most likely reason for this is that the majority of our clients smoke cigarettes so they use the filters from them. In a study carried out within our service by nursing staff in the addiction services, 93% reported smoking cigarettes in the last three months (James et al, 2008).


Ideally, staff and clients should have a shared view about service users’ health needs. It is therefore necessary for healthcare professionals to develop better strategies for delivering safety messages to clients. Nurses often tend to focus advice on stopping injecting. This study shows we need to take a more proactive approach to incorporating safer injecting advice into daily interactions with clients.

The nursing department in the addiction services has a progressive health promotion committee, which provides up to date health information on a wide range of topics for clients on a monthly basis. One of the monthly topics could include safe injecting advice.

Actions implemented since the study was completed

The expansion of the addiction nurse role over the last decade has influenced changes in nursing practices. It is only in the past few years that nurses have started to discuss injecting practices with clients and to give health advice on safer injecting practices.

In the three years since this study was carried out, the nursing care plan committee, in collaboration with the study’s lead author, have completely redeveloped the nursing initial assessment for new clients starting treatment and for those already in treatment.

The assessment form now includes a detailed section on injecting practices. This assessment has helped nurses develop a rapport with clients and gives a valuable opportunity to discuss and highlight risk factors associated with injecting.

The nursing initial assessment also now incorporates a detailed section on skin integrity from which nurses can ascertain the presence of any abscesses or tissue damage as a consequence of injecting.

A new wound care plan has also been developed, with a detailed section on safe injecting habits. This care plan also includes a section on the suspected causes of the wound, which allows nurses to document possible causes.

The nursing assessment and wound care plan have been reviewed annually by the care plan committee and our clinical nurse specialists using a feedback questionnaire. This was given to nursing staff only for the first year but is now given to clients and nursing staff. The care plan committee reviewed the questionnaires to examine both the format and answers, and changes were made. These changes included format changes, wording and inclusion and deletion of some parts.  

The nursing initial assessment and the care plans are now used across the service, and have become an integral part of the nursing care provided. Outside agencies from North Dublin, GP practice nurses and nurses from the homeless service have requested copies for use in their areas.


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