The use of some substances can lead to dependency. This is a complex process and personal experience and may involve both physical and psychological elements.

It is worth noting that there is evidence that dependency is influenced by the drug itself but more so by the mental state, attitude and beliefs of the person involved and the social and physical setting they are in. (See drug set and setting; see Rat Park)

People can remain dependent on a substance for the rest of their lives – as is fairly common, in the case of caffeine and tobacco users, for example and people on some medications. Breaking a dependency can involve repeated attempts of avoiding relapse during and after physical and psychological withdrawal symptoms which can be very unpleasant and in the case of some substances, like alcohol for example, life threatening.

Dependency is a useful and objective way of explaining the nature and experience of problem drug use. However, in creating the notion that there are hierarchies of different types of dependence – physical and psychological - it can misdescribe the experiences of people with a substance problem and lead to stigma and misunderstandings that disempower people.

The term dependency can narrowly refer to a person’s need to use a substance so that they can prevent symptoms of withdrawal. Withdrawal from some substances can be measured and viewed objectively by observing physical manifestations – pulse rate, vomiting, sweating, cramps, tremors and behaviours such as restlessness, inability to sleep and mental states like fixations including cravings, anxiety or low mood or suicidal ideation. Most people report that their dependency has physical and psychological aspects.

Beyond this narrow definition there are looser definitions – people who are dependent on substances will often speak about using substances to ‘feel normal’ or to ‘be able to function’ (see self-medicating).

In some discourses – medical discourse but also in media and political and public discourses - a strict distinction is sometimes made between physical dependence – those withdrawal symptoms that are observable by a doctor, for example, and psychological dependence – those which a person with a dependency reports, for example.

Unnecessary dispute is caused by the view that physical dependency is more serious than psychological dependency. This view is hard to justify except perhaps in the case of dependency on substances like alcohol where withdrawal requires medical supervision and can be fatal. But this is a very short term situation. People dependent on alcohol may experience psychological aspects to their withdrawal long after the physical danger of physical withdrawal has passed.

People with psychological dependences are sometimes portrayed as weak or inferior or lacking resolve when compared to people who have a physical dependency. Such notions are ill-founded and are disempowering and stigmatising. They are also unhelpful in supporting people who have a substance problem.

Some substances may readily create physical dependence in people than other substances however, the social and psychological circumstances of the person involved are highly significant. (See addictive).

Another issue is the description of withdrawal symptoms. Some medical and other discourse dismissively describes withdrawal symptoms; for example, in describing withdrawal from opiate dependence as ‘like a flu’. This is to underestimate the subjective element in this which is only partially understood. People with a dependence widely report that withdrawal can be deeply unpleasant. The subjective perception of pain and discomfort is very real to the person who experiences it. It may be that physical pain and discomfort can seem intolerable or deeply unpleasant for someone who has regularly used opiates that affect the perception of pain for a long time.

On the other hand, for some people similar withdrawal may be less problematic. This is likely to do with the personal and social circumstances in which people experience withdrawal (see drug set and setting; see Vietnam Veteran Studies). There is a common misunderstanding that fear of withdrawal or the unpleasant nature of withdrawal is the significant reason for people continuing to use substances or that, consequently, anything that can ease symptoms of withdrawal is a ‘cure’. This is based on a misunderstanding of the drivers of problem substance use (see poverty; see self-medicating; see adverse childhood experience; see trauma; see Rat Park).

In terms of wider political discourse, the term dependency is used in a disparaging manner analogous to its use in drugs discourse – terms such as ‘welfare dependency’ – are used in ideological opposition to social security, for example.