Page last updated
Monday 29th Jun 2026
Page written by
Victoria McCann
Opioid addiction can develop in ways less obvious than other substances. For many people, the addiction to opioids begins not with a street drug but with a prescription. Opioids given by a doctor can serve to manage severe pain, and even when taken as directed, the addiction can develop more quickly than anyone expects.
We’ll explain what opioids are, why dependency develops, how to recognise it, and what recovery broadly looks like. We’re here to show you the picture of opioid recovery, without pushing you towards anything you aren’t yet ready for.
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What are opioids?
Opioids are a class of medicines broadly used to reduce pain. They include prescription medicines such as codeine, tramadol, morphine, oxycodone, and fentanyl, as well as heroin, which is an illegal opioid derived from morphine. Synthetic opioids, manufactured compounds designed to act on the same receptors, are also becoming an increasingly large problem in the drug supply across Europe.
You will sometimes see the terms ‘opiate’ and ‘opioid’ used interchangeably. In the context of opiate drug addiction, the two terms describe the same condition. Opiates refer to naturally occurring compounds derived from the opium poppy. Opioids are the broader term for the whole class, including synthetic and semi-synthetic versions. Throughout this page, we use ‘opioid’ as the umbrella term.
Opioids are effective medicines for short-term and end-of-life pain management. But the addiction of opioids is something most people do not anticipate when they first receive a prescription. The fact that opioid addiction develops covertly can make it uniquely difficult to manage.
How does opioid addiction develop?
Opioids work by triggering the release of chemicals in the brain’s reward system. For most people, this produces relief from pain and, often, a sense of calm or wellbeing. The brain is behaving exactly as opioids are designed to make it behave. The difficulty begins when the brain starts to adapt.
With repeated use, the brain adjusts to the presence of opioids by producing fewer of its own natural pain-relieving chemicals and becoming less responsive to the drug’s effects. This is called tolerance, wherein taking the same dose again produces less relief than before. For someone using opioids to manage pain, this can feel as though the medicine is no longer working, because in practical terms, it is not. The natural response is to need more to achieve the same effect.
Over time, physical dependence develops. At this point, the brain has adjusted its baseline functioning around the presence of opioids. Reducing or stopping the drug disrupts that balance sharply, producing withdrawal symptoms that can feel physically overwhelming. Research published in Cell and Molecular Neurobiology has described this process as a homeostatic drive, meaning the brain’s attempt to maintain stable functioning in the face of persistent external changes to its signalling systems (Gledhill and Babey, 2021). It is the body responding to the sudden absence of something it has come to rely on at a neurological level, not a choice.
This is the experience that many people find impossible to explain to those around them: not wanting to continue, but finding that stopping feels unbearable. It is also why labelling opioid dependency as a “failure of willpower” does not stand on solid foundations.
Why opioid dependence can develop through a prescription
Opioid dependency often begins with prescribed medication. Someone is in pain. A doctor prescribes an opioid. The medicine works. Over time, the dose may need to increase to maintain the same level of relief. By the time a problem becomes visible, the person may have been following their prescription carefully and may have had no intention, or awareness, of developing a dependency.
A 2025 national cohort study published in Communications Medicine, which followed over 750,000 opioid-naive individuals in Sweden, found that the most significant risk factor for developing long-term opioid use was not a characteristic of the individual. It was receiving an opioid prescription itself (Kruger et al., 2025). Of those who received an initial prescription, 8.1% went on to use opioids long-term. The researchers noted that the pharmacological properties of opioids, specifically tolerance and physical dependence, mean that receiving a prescription carries inherent risk regardless of who receives it.
"I contacted Castle Health [formerly CATCH Recovery] seeking guidance and options to support a relative who was having a difficult time both with addiction and other mental health concerns. The team were incredibly kind and informed, they took the time to go through all the options with me and helped us plan how to approach the matter. Fortunately the person has now been receiving care from Castle Health for several months and is doing really well. A big thank you to the wonderful team."
How do I know if I’m dependent on opioids?
Recognising addiction to opioids symptoms in yourself is harder than it sounds. For many people, the shift from use to dependency happens slowly and silently. Physical signs that dependency may have developed include:
- Needing a higher dose than prescribed to achieve the same level of pain relief
- Experiencing physical symptoms such as sweating, nausea, muscle aches, or anxiety when a dose is missed or delayed
- Finding that the time between doses feels increasingly difficult to manage
- Continuing to use opioids despite concerns about the effect on your health, relationships, or daily life
Psychological and behavioural signs can include:
- Low mood, irritability, or anxiety between doses
- Spending increasing time thinking about medication or making sure you have enough
- Withdrawing from activities or relationships that once mattered
- A growing sense of secrecy around your medication use
The clinical criteria for opioid use disorder, as defined in the DSM-5, include a cluster of cognitive, behavioural, and physical symptoms. Yet these exist on a spectrum. Dependency does not have a single entry point, and the presence of even a few of these patterns is often a serious point of concern.
Signs of opioid addiction in people using prescribed medication
For people using opioids under a prescription, the signs can look different from those associated with illicit drug use. Dose escalation, taking more than prescribed or taking doses closer together than directed, is often the earliest visible sign.
You might also notice that opioids are being used for reasons beyond the original pain, for example to manage stress, anxiety, or low mood, or to feel able to cope with the day. This is the brain’s reward system responding to a substance that reliably reduces discomfort, also serving as a sign that dependency has moved beyond physical pain management.
Why are opioids addictive? The role of withdrawal
Understanding why people find it so difficult to stop using opioids requires understanding what opioid addiction withdrawal involves. Opioid withdrawal is not simply discomfort. For many people, it is a significant physiological event that the brain and body experience as a kind of crisis.
When opioids are present, they suppress certain signalling systems in the brain. When they are removed, those systems rebound sharply. According to the American medical reference StatPearls (Shah and Huecker, 2023), the principal site in the brain that triggers opioid withdrawal is the locus coeruleus, a region responsible for producing noradrenaline, which regulates arousal, anxiety, and stress responses. When opioids are removed, this region becomes overactive, producing a cascade of physical and psychological symptoms.
Opioid withdrawal symptoms typically include:
- Severe anxiety and restlessness
- Muscle aches and cramps
- Sweating and chills
- Nausea, vomiting, and diarrhoea
- Rapid heartbeat and raised blood pressure
- Insomnia
The timeline varies depending on the type of opioid. Short-acting opioids such as codeine or heroin produce symptoms that begin within hours of the last dose. Longer-acting opioids such as methadone may not produce symptoms for 30 to 36 hours, but withdrawal can last significantly longer. In both cases, the experience can feel tumultuous, which is why stopping suddenly is neither realistic nor safe without medical support.
This is also a significant driver of continued use. For many people, the addiction opioids creates is sustained not by desire for the drug’s effects, but by the need to avoid withdrawal. Understanding this changes the question from “why someone will not stop,” to “what would make it possible to stop safely?” For detailed information on what opioid detox involves and how it is managed medically, visit our opioid detox and withdrawal page.
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Who is at risk of opioid addiction?
Opioid dependency does not develop at random, but it also does not follow a predictable profile. Research points to a cluster of risk factors. None of these are absolute predictors, and none of them mean that dependency was inevitable or deserved.
According to the European Union Drugs Agency (EUDA, 2021), social exclusion and disadvantage are both a risk factor for opioid dependency and a frequent consequence of it. Effective treatment needs to address multiple dimensions, not just the pharmacological one.
Known risk factors include:
- A personal or family history of substance dependency
- Chronic pain conditions, which increase both exposure to opioids and the duration of use
- Prior trauma, post-traumatic stress disorder (PTSD), anxiety, or depression. This is not because these experiences directly cause opioid dependency, but because opioids are effective at temporarily relieving emotional as well as physical pain. Research published by the National Institutes of Health in the United States (Horn et al., 2026) identifies these conditions as among the most established co-occurring risk factors
- Receiving an initial opioid prescription in a primary care setting rather than for an acute injury. According to the 2025 Swedish cohort study (Kruger et al., 2025), this is associated with three times the odds of long-term use
- Social factors including isolation, unemployment, and limited access to non-opioid pain management or mental health support
It is also worth noting that women are, on average, more likely than men to be prescribed opioids, to receive higher doses, and to use them for longer periods. This means the risk picture is not uniform across gender, even if the experience of opioid dependency cuts across all demographics. A multinational European cohort study published in Frontiers in Pharmacology (Xie et al., 2025) found that risk factors for prolonged use, including chronic pain, mental health conditions, and older age, are common across European populations.
Opioid addiction and mental health
For many people, opioid dependency and mental health difficulties do not exist separately. They are closely linked, and often each makes the other harder to manage.
Depression and anxiety are among the most commonly co-occurring conditions in people with opioid dependency. Sometimes the mental health difficulty came first, and opioids became a way of managing pain that had no other adequate outlet. Sometimes sustained opioid use itself produces or deepens low mood, emotional blunting, and anxiety, particularly as withdrawal begins to intrude on daily life.
Addressing opioid dependency without looking at the mental health picture alongside it is likely to be incomplete. At Castle Health, we work with the whole person, not just the substance use in isolation. If a co-occurring mental health condition might be part of your experience, that is something we are equipped to assess and support from the start of treatment.
Recovery from opioid addiction is possible, but it takes time
Recovery from opioid dependency is real. The evidence for it is strong. Across pharmacological treatment, psychological therapy, and combined approaches, research consistently shows that people with opioid use disorder can and do achieve long-term recovery.
According to EUDA (2021), effective long-term treatment for opioid dependency often involves multiple treatment episodes and combinations of approaches. Opioid agonist treatment using medicines such as methadone or buprenorphine is the most established pharmacological approach, and evidence shows it reduces both illicit opioid use and mortality. Its effects are further enhanced when combined with psychosocial support.
What the evidence also shows is that recovery is rarely a single event. It is a process, and for most people it involves more than one episode of support. Periods of greater stability and periods of difficulty are both part of the process. Relapse is common, and it is a recognised feature of what is, clinically, a long-term condition. It is not a sign of failure. Understanding that relapse does not equate to failure can make what feels like an “unlit path” easier to navigate.
Effective treatment for opioid dependency typically combines medically asissted detox with psychological therapy. Approaches such as Cognitive Behavioural Therapy (CBT), motivational interviewing, and group therapy address the patterns of thinking and behaviour that sustain dependency. Detox addresses the physical component. Aftercare and ongoing support are not optional extras. They are part of what makes recovery last.
If you want to understand what treatment actually involves, our opioid addiction treatment page covers this in detail. If you are not ready for that yet, this page will be here when you are.
If someone in your life is using opioids and you’re worried
Recognising that someone close to you has developed a dependency on opioids, and not knowing what to do with that, is one of the hardest positions to be in. You can see what they may not yet be able to see. You know something is wrong. But knowing it and knowing how to help are two different things.
The most useful thing you can do at this stage is understand what opioid dependency actually is. Dependency is not a choice, and it is not a reflection of character. It is a medical condition with a neurological basis, and it responds to medical and therapeutic treatment. Seeing it as a medical condition changes the way many people approach the conversation, as well as what’s expected.
When it comes to talking to the person you are worried about, timing and tone make a significant difference. Conversations that happen during withdrawal, or in the immediate aftermath of a difficult incident, rarely land well. Conversations that come from a place of genuine concern rather than judgement are more likely to be heard. That does not mean there are no limits, or that concern cannot be expressed directly, but that connection tends to open doors that confrontation closes.
Family therapy is part of what we offer at Castle Health, because opioid addiction affects everyone in a household, not just the person taking the drug. If you would like to talk through your situation with someone before making any decisions, we are here for that, too. You do not need to have a plan before you get in touch.
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Frequently asked questions about opioid addiction
Is opioid addiction the same as opioid dependence?
These terms are often used interchangeably, but they’re clinically distinct. Physical dependence, meaning the body has adapted to the presence of opioids and will produce withdrawal symptoms without them, can develop without the loss-of-control element that characterises addiction. People can find stopping extremely difficult even without meeting the full clinical criteria for opioid use disorder. For that reason, we should remember the importance of the distinction, because it explains why stopping is difficult even for people who do not consider themselves dependent in the broader sense.
Can you become dependent on opioids if you take them as prescribed?
Yes. Physical dependence can develop through prescription use, particularly over longer periods or at higher doses. It does not mean that everyone who takes prescribed opioids will develop a problem. But research published in Communications Medicine has described the receipt of an opioid prescription as itself the primary risk factor for long-term use, not any particular characteristic of the person receiving it (Kruger et al., 2025).
What is the difference between opiates and opioids?
Opiates are naturally occurring compounds derived from the opium poppy. Morphine, codeine, and heroin fall into this category. Opioids is the broader term that covers the whole class, including synthetic and semi-synthetic compounds designed to act on the same receptors in the brain. Fentanyl and methadone are examples of synthetic opioids. In clinical and everyday use, ‘opioids’ is now the standard umbrella term, and that is the convention used throughout this page.
Are synthetic opioids more dangerous than prescription painkillers?
Synthetic opioids, particularly illicitly manufactured fentanyl and its analogues, are significantly more potent than most prescription opioids. Research published in JA Open (Lambert, 2023) notes that fentanyl is approximately 80 times more potent than morphine, which means the margin between a dose that produces an effect and one that causes overdose is considerably smaller. The contamination of the illicit drug supply with synthetic opioids has increased overdose risk substantially across Europe. EUDA data from 2023 recorded a significant increase in seizures of nitazenes and other novel synthetic opioids across EU member states (EUDA, 2025). That said, risk is not simply a function of substance type. Tolerance, route of use, and whether other substances are involved all significantly affect the picture.
Where can family members and friends get support?
Opioid dependency affects the people around the person using it, not just the person themselves. If you are worried about someone in your life, support exists specifically for you, not only for them. Family therapy and support for making sense of what you are witnessing are both available through Castle Health. Reaching out does not require the person you are worried about to be ready for treatment. You can take that step for yourself, at any point.