
Understanding Opioid Addiction

Key Takeaways
- Opioids are prescribed drugs used for pain management, e.g., tramadol, fentanyl, codeine and morphine
- Due to their euphoric effects, opioids can be misused
- The term ‘opioids’ is widely used to describe opiates (naturally occurring compounds) and opioids (manufactured compounds) that can bind to opiate receptors
- Opioid addiction, also known as opioid use disorder (OUD), is a chronic, relapsing brain disease which occurs when individuals persistently use opioids despite negative consequences
- Physical dependence and tolerance to opioids can develop with persistent use and withdrawal symptoms, such as pain and vomiting, can occur when use is reduced or stopped
- Opioid overdose is a medical emergency with three common signs: breathing difficulties, pinpoint pupils and unconsciousness. Call 999 immediately if you suspect someone is experiencing signs of an overdose
- Effective opioid addiction treatments often involve a combination of medical and behavioural therapies
- The FDA has approved three medications for use in drug addiction treatment. These are methadone, buprenorphine and naltrexone
- Counselling, behavioural therapies, such as cognitive behavioural therapy (CBT), and residential rehabilitation are also indicated in opioid and opiate addiction treatment
- Support groups, such as SMART Recovery and Narcotics Anonymous, can also help maintain recovery from opioid addiction
Table of Contents
What Are Opioids?
Opioid drugs are commonly prescribed for pain management. Examples of opioids include tramadol, fentanyl, codeine and morphine.1
These drugs interact with opioid receptors in the brain and body, leading to various effects. By binding to these receptors, opioids block pain signals travelling from the brain to the body whilst releasing large amounts of dopamine. This dopamine release can strongly reinforce taking the drug, prompting individuals to repeat use.
Opioids make individuals feel happy and relaxed in the short-term but they can also have harmful effects. These include confusion, drowsiness and slowed breathing.
Opioids can be taken by mouth, snorted or injected.2
When people misuse opioids over prolonged periods, they are susceptible to developing tolerance, dependence and withdrawal effects. Those who are addicted to opioids can be found to be using prescription or illicitly obtained substances. The majority of individuals who are opioid-dependent use illicit forms, such as heroin, however, a growing number are using prescription opioids.
Opioids can be effective in managing pain when prescribed by a healthcare professional. However, the use of opioids without medical supervision can lead to dependence and overdose.1
Opioid overdose occurs when an individual uses sufficient quantities of an opioid to produce life-threatening effects or fatal consequences. During overdoses, breathing slows down significantly, reducing the supply of oxygen to the brain which can result in permanent brain damage, coma or death.2
World Health Organization (WHO) estimates reveal that around 125,000 individuals died of opioid overdose in 2019. Non-fatal overdoses are several times more common than fatal overdoses.1
The Difference Between Opiates and Opioids
Opiates are naturally-occurring compounds derived directly from the opium poppy plant. Examples of opiates include heroin, codeine and morphine.
Opioids are manufactured compounds that can bind to opiate receptors. Examples of opioids include fentanyl and methadone.3,4
As both groups of compounds are widely known as “opioids”, we will use this term for consistency throughout this page. Additionally, the term “opioid receptors” is commonly used, so we will utilise this term.3
Prescription opioids used for pain relief are generally safe when taken for a short time and as prescribed by your health care provider. However, opioid misuse and addiction are still potential risks.

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Opioid Addiction
How Does Opioid Addiction Occur?
Due to the euphoric effects of opioids, they can be misused. Misuse can involve taking a prescription opioid to achieve euphoric effects, taking it in higher doses than prescribed or taking another person’s medication.2
By stimulating the reward pathway in the brain and bringing about this feeling of happiness or euphoria, opioids can become addictive for some individuals.4
Diagnosing Opioid Use Disorder (OUD)
Addiction can also be referred to as a substance use disorder. The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) provides helpful guidance for diagnosing these disorders. It recognises that individuals are not equally susceptible to developing addiction and that this depends on a variety of factors.
DSM-5 recognises opioid use disorder (OUD) as a condition that arises when opioids are persistently used, despite negative consequences.
Substance use disorders such as OUD can lead to an array of negative effects. These form the DSM-5 criteria, which are used to assess and grade the severity of substance use disorders. Problems arising from OUD can include:
- Inability to reduce or stop use of opioids
- Using opioids in larger doses or for longer than recommended
- Opioid cravings
- Investing significant amounts of time to obtain, use or recover from opioids
- Continued use despite relationship breakdowns
- Continued use despite potential dangers
- Continued use despite physical and/or psychological conditions that may be caused or exacerbated by opioids
- Inability to fulfil responsibilities at home, work or school due to opioid use
- Giving up significant work, social or recreational activities due to opioid use
- Development of tolerance, where more opioid is needed to achieve desired effects
- Development of withdrawal symptoms when use is reduced or stopped, which can be alleviated by taking more opioid
These 11 criteria provide insights into the extensive impact that opioid addiction can have on an individual’s life. DSM-5 also allows healthcare professionals to grade the severity of opioid addiction through the number of symptoms present, from those listed above. If two or three symptoms are present, this indicates mild OUD, four or five symptoms suggest moderate OUD and six or more symptoms highlight severe OUD.5
OUD is a chronic, relapsing brain disease that significantly impacts individuals’ and their families’ lives. The relapsing nature of the disease means that an individual can be at risk of relapse following a period of recovery.4
If you recognise any of the effects of opioid addiction from DSM-5, it is important to reach out and seek an assessment by a medical professional. This can help to secure a diagnosis to inform effective treatment for you or a loved one.5

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Factors Influencing Opioid Addiction
Individuals are not equally susceptible to addiction. A complex interaction between various biological and environmental factors influences addiction risk. For example, teenagers and individuals with physical and mental health conditions are at increased risk of using and becoming addicted to substances. In addition, early use and smoking or injecting substances also heightens the risk of developing addictions such as OUD.6
Risk factors for OUD include4,6:
- Access to opioids
- Existing or previous substance use disorder
- Family history of substance use disorder
- Exposure to substance use by friends or family members
- Lack of parental supervision
- Inability to withstand peer pressure
- Co-occurring mental health conditions like post-traumatic stress disorder or depression
- Childhood trauma or abuse
- Conduct disorder in childhood or adolescence
- Local poverty
On the other hand, some protective factors can help to reduce the risk of developing OUD. These protective factors can include:
- Attentive and nurturing parents
- Positive relationships
- Belief in your own abilities (self-efficacy)
- Good educational performance
- Anti-drug policies in school
- Positive resources within local neighbourhoods
Areas of the brain like the prefrontal cortex, which is responsible for decision-making and regulation of emotions, are still developing during adolescence. This puts teenagers at a higher risk of trying and continuing to use drugs, which can exert profound and long-lasting consequences.6
Opioid Withdrawal
Withdrawal Symptoms
Opioid use can produce various side effects. These include nausea, constipation and immune system suppression. Opioids also influence hormone levels, which can lead to reduced libido in men and disturbed menstrual patterns in women.4
In individuals who have developed opioid tolerance and dependence, reducing or stopping opioid use can produce significant effects.
Severe withdrawal symptoms can develop a few hours after last use and can include:
- Substantial cravings
- “Cold turkey” – cold sensations with goosebumps on the skin
- Disturbed or reduced sleep
- Bone and muscle pain
- Vomiting
- Diarrhoea
- Involuntary leg movements
The United States Food and Drug Administration (FDA) has approved treatments which can help to ease these withdrawal effects. A non-opioid medication, lofexidine, was approved by the FDA in 2018 to aid reduction of withdrawal symptoms. In addition, the FDA has also approved NSS-2 Bridge, a device that can be used to ease the effects of withdrawal for up to five days during the acute phase of opioid withdrawal.2
Withdrawal Timeline
Determining a precise timeline of events for opioid withdrawal syndrome is difficult, however, the type of opioid used can help in predicting the onset and duration of withdrawal effects.
Withdrawal from short-acting opioids, such as heroin, can typically produce symptoms at 8–24 hours following last use, which can persist for between 4–10 days.
Withdrawal from long-acting opioids, such as methadone, can result in withdrawal symptoms being observed at 12–48 hours after last use, which tend to persist for 10–20 days.7
Opioid Overdose
Opioid overdose is a significant risk associated with opioid use, addiction and relapse following a period of abstinence. Overdoses can have fatal consequences.4
Opioid overdoses represent medical emergencies that require immediate intervention. Understanding the appropriate actions can save lives. When an overdose is suspected, it is important to look out for three classic signs: breathing difficulties, pinpoint pupils and unconsciousness. If these are present, you should call emergency services immediately and administer naloxone if this is available to you. Providing basic life support and supporting the person until help arrives are also crucial steps in helping someone through an overdose event.1 After this event, the person should receive medical and psychological support to aid long-term recovery.4
If you are searching for guidance to help someone in crisis, please call the emergency services. The information on this page is not intended as a substitute for medical intervention.
Learn more about the management of opioid overdoses here.












Treating Opioid Addiction
Opioid addiction treatment can involve different medications and behavioural therapies. A combination of medical and behavioural approaches can be most effective in managing OUD. Long-term treatment is recommended to manage this chronic, relapsing disease.
Medical Treatments
Three medications have been approved by the FDA for use in opioid addiction treatment. These are:
- Methadone
- Buprenorphine
- Naltrexone
Methadone and buprenorphine are opioids. As such, they can block the effects of other opioids, reduce cravings and ease withdrawal symptoms. Buprenorphine tends to be given along with naloxone and can be provided by GPs and pharmacies, unlike methadone which can only be accessed through specialist facilities.
The doses of methadone and buprenorphine used in OUD management are not sufficient to produce the euphoria or high obtained from opioid use.
Naltrexone is a non-opioid medication which blocks the binding of opioids to opioid receptors. This treatment tends to be provided as an injection that lasts for four weeks.
The duration of treatment required will depend on the individual and the severity of the OUD. Some patients require medical treatment with these drugs for many years or even decades.
Behavioural Therapies
Counselling and behavioural therapies can provide individuals with new skills and insights into their addiction which can aid recovery from OUD. Counselling or therapy sessions can occur in-person or online. There are various approaches that can be helpful in OUD, including:
- Cognitive Behavioural Therapy (CBT): Helps individuals with OUD to understand how their thoughts and emotions are influencing certain behaviours
- Motivational enhancement therapy: Addresses mixed feelings about opioid use and encourages motivation and dedication to managing an OUD
- Contingency management: Offers rewards to reinforce positive behaviours, such as abstinence from opioids
- Family counselling: Provides education to support understanding of OUD as a disease and coping strategies for managing harmful consequences
- Support groups: Mutual support from others experiencing addiction and recovery can reduce isolation and foster motivation for maintaining sobriety. Groups such as SMART recovery8 and Narcotics Anonymous9 can be instrumental in providing support during the recovery process
Residential Rehabilitation
Medically managed opioid withdrawal is a form of detoxification that can occur within residential rehab facilities, such as Castle Craig. Providing medications to help manage withdrawal symptoms is a component of medically managed withdrawal. This form of detoxification can be more successful as individuals aren’t as motivated to use opioids to relieve uncomfortable withdrawal symptoms.4
How Can Castle Craig Help?
Addiction Rehabilitation at Castle Craig
Castle Craig offers a world-renowned service for addiction and treats an array of drug addictions. For example, our team has vast experience in managing fentanyl addiction.
At Castle Craig, our medically-managed detoxification ensures patient safety in a comfortable environment. Our primary focus is maintaining the comfort of each patient, minimising anxiety and making them feel at ease with round-the-clock care. Our treatment is evidence-based and our independent outcomes studies provide further evidence that our treatment works for the majority of patients. 91.8% of our 2015 cohort, who were experiencing alcohol, drug or gambling addictions, demonstrated improvements at follow-up. 73.4% maintained abstinence at approximately 1 year after discharge.10
Alongside a supervised medical detox and an individualised treatment plan, Castle Craig works to address emotional and psychological issues that may have contributed to opioid misuse. Getting to the route of opioid addiction is important in reducing the risk of relapse.
Start Your Journey to Recovery with Castle Craig
Opioid addiction can be all-consuming so it can be challenging to imagine a life free from addiction. A vital first step is recognising that you may be struggling with addiction and that you’re willing to accept that you need help.
Castle Craig has successfully treated addiction for over 30 years. We have a specialised opioid addiction treatment programme in place, due to the specific requirements and needs of opioid users. Our programme features a clinically managed detox and withdrawal process. Our team goes above and beyond to ensure your comfort and safety throughout your stay and focuses on the person, not the addiction.
We are committed to providing aftercare well after the residential stay is over, with a 6 month aftercare plan set up with your specific recovery journey requirements in mind.
If you think you may be suffering from opioid addiction and are ready to seek help, please don’t hesitate to contact us today to find out more about the treatment options available to you.
Lynda’s Recovery Journey
Lynda shares her inspiring journey from the depths of addiction to a life in recovery with Castle Craig. Listen to her powerful story as she reflects on past struggles and how rehab transformed her life.
How Can Castle Craig Help?
Who will I speak to when I call Castle Craig?
When you call you will reach our Help Centre team who will give you all the information you need to help you decide whether to choose treatment at Castle Craig. If you decide that you would like to have a free screening assessment you will be asked a series of questions to build up a picture of your medical and drug use history as well as any mental health issues you are facing. If you decide you want to proceed with treatment you will be put in touch with our admissions case managers who will guide you through the admissions process.
How long is the rehab programme?
Residential rehab treatment starts at 4 weeks and can go up to 12+ weeks. Research shows us that the longer you stay in rehab and are part of the residential therapy programme, the longer the likelihood of continued abstinence and stable recovery.
How do I pay for rehab?
One concern we sometimes hear from people is how they will fund their rehab treatment. You can pay for treatment at Castle Craig privately, or through medical insurance, and some people receive funding through the NHS. The cost of rehab varies depending on what kind of accommodation you choose.
What happens at the end of my treatment?
Castle Craig thoroughly prepares patients before departure by creating a personalised continuing care plan which is formulated following discussions with the medical and therapeutic team. We offer an online aftercare programme which runs for 24 weeks after leaving treatment, in order to ensure a smooth transition back into your everyday life. Patients leaving treatment automatically join our Recovery Club where they can stay connected via our annual reunion, events, online workshops and recovery newsletters.