Abstract

The development of physical dependence is different in both alcohol and heroin. The repeated use of both alcohol and heroin can lead to physical dependence as a result of the neuroadaptations that occur. However, they both produce different effects and act through different biological processes. For alcohol, it’s the glutamate and gamma-aminobutyric acid (GABA) regions of the brain that are affected, while heroin mainly activates the mu receptors in the brain. In this paper, we compare the short-term and long-term withdrawal symptoms for both substances, as well as different available treatment options. Alcohol withdrawal may include symptoms like anxiety, irritability, shaking, sweating, nausea, insomnia and in severe cases, seizures or serious physically damaging episodes. Heroin withdrawal is commonly associated with symptoms like increased respiratory rate, anxiety, yawning, excessive sweating and stomach cramps. Whilst both substances produce a range of physical and psychological symptoms, it has been claimed that alcohol withdrawal symptoms are more dangerous than heroin (Lee & Forsythe, 2011), carrying a greater risk of life-threatening complications compared to heroin. Additionally, treatments for both differ. Treatment for alcohol withdrawal may require medication or could be helped through behavioural therapies (e.g., cognitive behavioural therapy), while treatment for heroin withdrawal is mainly medication. 

Introduction

Alcohol and heroin are both addictive substances where people can experience different dependence behaviours and withdrawal symptoms. Addiction refers to a chronic (lifelong) condition involving compulsive seeking and taking of a substance or performing an activity despite the negative or harmful consequences (Cleveland Clinic, 2023). Physical dependence refers to a state where an individual’s body becomes reliant on a substance (Durning, 2022), developing when the body is repeatedly exposed and adapts to the continuous presence of the substance. When a substance is removed, or the dosage is significantly reduced, dependence may manifest through a series of unpleasant withdrawal symptoms that may arise (EBSCO, 2024), including common symptoms like trembling, effects on appetite, sweating and anxiety (Sharp, 2024). This paper will highlight physical dependence through the comparison of withdrawal symptoms associated with alcohol and heroin, with a specific focus on the short-term and long-term effects of withdrawal. Although both alcohol and heroin can develop dependence, the withdrawal experience may be very different, as each substance interacts differently with the nervous system (Gupta, Gokarakonda & Attia, 2024).

Throughout the paper, there will be an examination of the processes that contribute to physical dependence and the reasons for withdrawal. There will be a comparison between the more short-term symptoms that may occur from alcohol and heroin, as well as the more persistent symptoms that may occur. Additionally, there will be a discussion of the medical risks, treatments and recovery from withdrawal associated with alcohol and heroin. Through the comparison of alcohol and heroin, the paper aims to distinguish between the different symptoms that may occur, highlighting that not all substances will produce the same withdrawal experiences. 

First, it is essential to define the remaining key terms that will be used within the paper. Alcohol is a nervous system depressant that easily alters the behaviour of individuals (Psychology Today, 2019). Alcohol interferes with the brain’s communication pathways and can actually affect how the brain works and looks. Long-term or heavy drinking can cause alterations in the neurons and may reduce their size (National Institute on Alcohol Abuse and Alcoholism [NIAAA], 2022). It has a “depressive” effect on the brain system, slowing down brain function and changing the nerve pathways. Over time, the central nervous system adjusts to the presence of alcohol, and when there is a sudden drop in the levels, the brain stays in this overactive state, leading to withdrawal symptoms. The withdrawal symptoms commonly associated with alcohol include headaches, mood swings, anxiety and nausea, and in severe cases, seizures or hallucinations may occur (DiLonardo, 2023). Heroin is a highly addictive drug and is a rapidly acting opioid (United States Drug Enforcement Administration, 2000). Repeated heroin use changes the physical structure of the brain, creating a long-term imbalance in neuronal and hormonal systems that cannot be easily reversed. Additionally, it produces profound degrees of physical dependence, with withdrawal symptoms occurring within a few hours after the last time it was consumed, with the symptoms including restlessness, muscle pain, insomnia and vomiting (National Institute on Drug Abuse [NIDA], 2018).

Physical Dependence and Withdrawal

Alcohol physical dependence development

When the brain becomes accustomed to the effects of alcohol through repeated consumption, alcohol dependence develops. This dependence is present in physical symptoms and is known as physical dependence. The brain’s reward and stress systems, which impact motivation and emotions, are impacted by alcohol. At first, alcohol can increase feelings of pleasure and reduce anxiety or stress. However, excessive and frequent drinking can alter these brain systems, weakening the effects of alcohol over time. As a result, individuals feel the need to drink more alcohol to achieve the same effect, which is known as tolerance (NIAAA, 2025). Glutamate and gamma-aminobutyric acid (GABA) systems in the brain are further impacted by alcohol. GABA helps calm brain activity, while glutamate increases brain activity. The brain adjusts to repeated alcohol consumption by increasing its response to glutamate and decreasing its response to GABA. This allows the brain to continue functioning while alcohol is present, but creates a physical dependence at the same time (Gilpin & Koob, 2008). The prefrontal cortex, which is involved in impulse control, self-control and decision-making, is also impacted by alcoholism. 

According to the NIAAA, these alterations may lead to compulsive drinking and difficulty quitting alcohol use despite its detrimental effects. Over time, drinking may continue to reduce anxiety, irritability or other uncomfortable feelings that occur when the effects of alcohol begin to wear off. Alcohol withdrawal occurs when an alcohol-dependent individual significantly reduces or stops their usual alcohol intake. Because the brain has adapted to the presence of alcohol, removing it causes the nervous system to suddenly become overactive. This hyperactivity can lead to symptoms such as anxiety, irritability, shaking, sweating, nausea, insomnia, increased heart rate and raised blood pressure. These symptoms may begin within several hours after the last drink and can become more severe during the following days. This occurs because the calming effects of alcohol on GABA are removed while increased activity of glutamate remains (American Society of Addiction Medicine [ASAM, 2020; World Health Organisation [WHO], 2019). The severity of withdrawal depends on factors such as the amount and duration of alcohol use and the person’s general health. Repeated withdrawal periods may also increase the risk of more serious withdrawal symptoms in the future (ASAM, 2020). 

Some people may experience alcohol-related hallucinations while remaining aware of their surroundings. In more serious cases, withdrawal can cause seizures and serious, physically damaging episodes. Another severe complication is delirium tremens, which may involve significant change in consciousness, hallucinations and heavy sweating. Delirium tremens develops later than milder withdrawal symptoms and is categorised as a medical emergency (ASAM, 2020; WHO, 2019). Although physical symptoms improve after the acute withdrawal period, symptoms such as anxiety, sleep problems, mood and cravings may continue for longer. Therefore, physical dependence develops through the brain’s repeated adjustment to alcohol. Withdrawal occurs when these changes remain after alcohol has been removed.  In order to get short-term relief from the discomfort of withdrawal, an individual may drink again to erase that discomfort, leading to a prolonged cycle of alcohol dependence and the raised risk of relapse (NIAAA, 2025).

Heroin physical dependence development

Heroin addiction is a disorder characterised by chronic relapsing and compulsion, and it is rooted in maladaptive plasticity of the brain’s neural circuits (Ma et al., 2019). Upon heroin ingestion, dopamine neurons release excessively. When the substance is abused, the overloads of dopamine tell the brain to stop its own production, which creates an adaptation in the brain’s neural circuits and natural reward system (Wei et al., 2018b). Addiction is furthered by the dysfunction of the brain’s prefrontal cortex that occurs with excessive use. These regions of the brain advance heroin cravings and impulsive use, eventually resulting in one losing power in their control over substance intake (Ma et al., 2019). Opioids, such as heroin, are especially addictive since they modify the brain’s limbic system, which is responsible for emotional regulation. When heroin enters the brain, it converts into morphine and creates a euphoric sensation. This sensation arises once the morphine binds to the mu-opioid receptors (MORs). The potency of the sensation depends on the dosage and how rapidly the drug is absorbed. After the initial sensation, heart function decreases, as does respiratory rate. This becomes dangerous because the slow breathing rate (bradypnea) increases the risk of coma and brain damage (NIDA, 2011). These disruptions increase stress hormones, which amplify feelings of depression and anxiety (Arrow Passage Recovery Centre, n.d.). Tolerance of heroin develops rapidly, meaning that as usage increases, much more is required to achieve the same effect. Physically, the body adapts to the presence of heroin, creating a dependence on it (NIDA, 2018).

Heroin withdrawal occurs when an individual who has become heroin dependent significantly decreases their usual dosage or completely stops taking the drug (House, 2025). With the repeated use of heroin, the body adapts to its presence and acts differently when it is reduced abruptly (NIDA, 2018). As a result, both psychological and physical withdrawal symptoms occur. Because heroin is a short-acting opioid (NIDA, 2018), these symptoms may occur as early as four hours after the last time it was taken, peaking within 48-72 hours. During the acute phase of withdrawal, early symptoms can include intense cravings for heroin, increased respiratory rate, anxiety, yawning, excessive sweating and stomach cramps (Khan & Makovkina, 2026). As the withdrawal progresses, protracted (long-term) symptoms like nausea, depression, diarrhoea, abdominal cramping and insomnia may occur when the persistent impairments are felt beyond acute withdrawal (Berger, 2024). Generally, acute (short-term) symptoms of withdrawal start within the first 6-24 hours of last use and last anywhere from 3-10 days, varying depending on the dosage and duration of use (Florimbio, 2024). The main physical symptoms usually subside after this period; however, symptoms like insomnia, mood changes and intense cravings for heroin can last much longer (Drug and Alcohol Clinical Advisory Service [DACAS], 2024). Some of the most distressing symptoms of opioid withdrawal stem from changes in the locus coeruleus (LC), a small nucleus located deep in the brain stem (Poe et al., 2020). These symptoms occur because of the repeated activation of mu receptors in the brain, as a result of heroin use before withdrawal. When heroin is removed after repeated use, the adapted neurons can become hyperactive because the inhibitory effects of the mu receptors have been lost. As a result, the nervous system becomes overactive, triggering anxiety, jitters, muscle cramps and diarrhoea (Kosten & George, 2002).

Relapse, Treatment and Behavioural Changes

Alcohol treatment

The treatment for alcohol dependence is divided into two main approaches: behavioural and medical.

Behavioural treatment includes cognitive behavioural therapy (CBT), motivational interviewing, and marriage and family therapy (Wang et al., 2020). Cognitive behavioural therapy refers to a type of therapy in which therapists lead the patients to realise the distortion and toxic elements in their thought processes, then reevaluate them in the light of reality (American Psychological Association [APA], 2017). CBT views alcoholic dependence as a learnt habit, which then leads to the application of therapeutic techniques targeted at the learning process. Thus, through the lens of CBT, alcoholic dependence is learnt through imitating role models and/or the positive reinforcements from experiencing the positive effects of alcohol, such as reduced stress and enhanced sociability. This causes individuals to view alcohol as the preferred way of coping (Kadden, 1994). In order to combat these impulsive cravings for alcohol, affected individuals must train both their interpersonal and intrapersonal skills in order to fulfil their needs without turning to alcohol abuse. CBT treatments for alcohol dependence are a well-established intervention with demonstrated efficacy (Magill et al., 2023). Multiple relapse prevention behavioural treatment methods are also widely used to ensure long-term stability after quitting alcohol abuse. These treatment methods include strategies such as minimising exposure to craving-triggering cues, attending self-help groups and engaging in pleasant activities. 

Medical treatments for alcohol dependence generally separate medication into three main medicinal uses: withdrawal, staying sober / reducing consumption, and insomnia (Matsushita, 2023). While supportive care can manage the aftereffects, there is no pharmacological agent currently that can actively reverse the intoxicating effects of alcohol once it is in the system (Miller, 1995). During the initial detoxification stage, severe alcohol withdrawal can present critical, life-threatening symptoms, such as seizures and delirium tremens (Schmidt et al., 2016). Chlordiazepoxide and diazepam are widely utilised as the clinical mainstay in treating alcohol withdrawal by smoothing out the dangerous spikes of withdrawal. Once a patient successfully clears the detoxification window, the clinical objective shifts towards relapse prevention. Food and Drug Administration (FDA)-approved medications like naltrexone and acamprosate are used to effectively reduce heavy drinking or maintain abstinence when combined with psychosocial therapy (McPheeters et al., 2023). In early sobriety, persistent insomnia is a key driver of early relapse (Brower et al., 2001). For this reason, medications such as benzodiazepine hypnotics or the newer z-hypnotics, zopiclone and zolpidem, can be prescribed for the treatment of insomnia (Hausken et al., 2009). Despite steady advancements in pharmacology, medical therapy alone has inherent limitations. Although medical treatments provide essential biological cures, their standalone therapeutic effects are relatively modest. In order to maximise their effects, they should be used in conjunction with extensive psychosocial therapy, such as cognitive and behavioural therapy (Miller, Book & Stewart, 2011).

Heroin treatment

There are multiple different approaches and treatments when working with heroin addiction. The treatment options that will be discussed are supervised injectable heroin (SIH) and pharmaceutical treatments. 

Supervised injectable heroin is the process where patients attend a clinic twice a day to have medical heroin injected to help prevent difficult withdrawal symptoms and treat the addiction (Ellefsen, Elise & Espen Ajo Arnevik, 2023). SIH is not considered standard treatment, like oral methadone maintenance treatment (MMT) or residential rehabilitation, so it is not usually a first choice (Strang et al., 2015). This treatment is mainly used for patients who do not respond to standard treatments: for example, people with opioid use disorder (OUD). People with OUD are at high risk for overdose before treatment and even higher risk when treatment ends, so it is important to have alternative treatments when the standard does not work (Ellefsen, Elise & Espen Ajo Arnevik, 2023). According to Riley et al. (2023), patients become motivated to start SIH and continue treatment for many different reasons, including worsening physical health, mortality concerns and periods of incarceration. Many patients stated that SIH reduced stress, increased their energy and hope, and allowed their brains to function for other daily activities besides finding and paying for illicit heroin (Ellefsen, Elise & Espen Ajo Arnevik, 2023). As stated previously, clinics are only open twice a day, so some patients have sought out illicit heroin at night to prevent withdrawal symptoms (Ellefsen, Elise & Espen Ajo Arnevik, 2023). It is important for SIH to be a long-term treatment solution because patients whose services are discontinued are at high risk of relapse (Riley et al., 2023). 

Heroin dependence can be treated through a combination of medications and pharmaceutical treatments to help manage withdrawal, reduce cravings and prevent relapse, allowing individuals to return to their heroin-free lives. Pharmaceutical treatments can be used during both the withdrawal stage and maintenance stages of recovery. Methadone, a slow-acting opioid agonist, can relieve withdrawal symptoms and cravings while providing a better long-lasting effect than heroin, making it useful for long-term maintenance treatments (Better Health Channel, n.d.; NIDA, n.d.). Buprenorphine, a partial opioid agonist, also relieves withdrawal symptoms and urges and can be given in long-lasting forms, lessening the need for constant clinic or pharmacy visits (Better Health Channel, n.d.).  Buprenorphine can also be combined with naloxone (more commonly known as nasal spray); the combination of the two is used for induction and maintenance treatment of opioid (narcotic) dependence (Mayo Clinic, n.d.). Naltrexone works differently because it is an opioid antagonist that blocks opioid receptors rather than triggering them. It therefore helps prevent relapse after a person has stopped using opioids, although it does not eliminate cravings. This means individuals must continue counselling and other support systems, important components of treatment when on naltrexone (Better Health Channel, n.d.; NIDA, n.d.). Medications can make withdrawal more manageable, as withdrawal symptoms may increase the likelihood of returning to heroin use; however, detoxification alone is not considered a complete treatment and should be followed by continued care (NIDA, n.d.). Stabilising physical dependence can reduce the need to continuously obtain heroin and allow individuals to focus on recovery.

Discussion

Alcohol and heroin dependence have multiple similarities, especially in the way that when they are used repeatedly, they can produce long-term changes in the brain and neural pathways, increasing the risk of relapse. Both heroin and alcohol dependence are chronic disorders, with relapse leading to changes in systems involved in motivation, self-control and reward. Although the two substances are different in the mechanisms involved, both can influence the dopamine-related reward pathways, meaning natural rewards such as food or interactions with peers become less reinforcing compared to the substances. This provides evidence to explain why cravings and relapse can be a significant problem even after the initial withdrawal period.

Although there are similarities, the biological mechanisms for alcohol and heroin dependence are very different. Heroin is a highly addictive and rapidly acting opioid that mainly acts on mu-opioid receptors (United States Drug Enforcement Administration, 2000), whilst alcohol mainly affects neurotransmitter systems like GABA, glutamate and dopamine (ASAM, 2020; WHO, 2019). During alcohol withdrawal, the nervous system can react very strongly because the inhibitory effects that are associated with alcohol use are removed suddenly, whilst the excitatory activity in the nervous system is still high. This produces withdrawal symptoms like anxiety, tremors, insomnia, mood and craving, with more severe, potentially life-threatening symptoms including hallucinations and seizures (ASAM, 2020; WHO, 2019). Withdrawal from heroin dependence also involves increased activity in the nervous system; however, it is associated more with a disruption of the opioid and stress systems.  Symptoms for heroin withdrawal include intense cravings for heroin, increased respiratory rate, anxiety, yawning, excessive sweating and stomach cramps (Khan & Makovkina, 2026). Whilst both substances produce a range of physical and psychological symptoms, it’s been claimed that alcohol withdrawal symptoms are more dangerous than heroin (Lee &  Forsythe, 2011), carrying a greater risk of life-threatening complications compared to heroin. 

While alcohol and heroin dependence both require long-term treatment, this review shows that their treatment approaches differ because of the way each affects the body and brain. The main similarity between the treatment options to cure addiction to substances like alcohol and heroin is that for the treatment to be successful, there needs to be a balance between medical and behavioural treatment (NIAAA, 2024). This process usually includes three steps. Firstly, acute stabilisation, meaning both treatments begin with supervised detoxification of the substance in the body to manage the withdrawal symptoms carefully. Then it moves on to the maintenance phase, where both treatment pathways establish long-term stabilisation to minimise cravings and prevent the occurrence of relapse. Alongside this, the treatment also integrates psychological and social support structures to ensure the well-being of the patient. To conclude and make sure the treatment is as effective as possible, doctors follow up in the long term with relapse prevention and support if desired rather than short-term intervention. For alcohol dependence, the medication works best with psychosocial therapy such as cognitive behavioural therapy (Magill et al., 2023). Similarly, heroin dependence is strongly recommended to combine medication with counselling and ongoing support (SAMHSA, 2021; NIDA, 2021). This could also be CBT or other therapies, including motivational interviewing, community reinforcement and contingency management.

One major difference is the use of SIH in heroin dependence treatment (Strang et al., 2015; McNair et al., 2023). Patients who do not respond to standard treatments receive medically prescribed heroin under supervision (Strang et al., 2015; McNair et al., 2023). In the long term, it can reduce the need to obtain illicit heroin and enable patients to become more present in their own lives (Strang et al., 2015; McNair et al., 2023). In contrast, treatments for alcohol dependence aim to reduce or eliminate alcohol consumption through medication such as naltrexone and acamprosate. Additionally, a key difference is the way medication is used in the long term. Methadone and buprenorphine are both medications used to replace opioids, in which they activate the opioid receptors in a controlled and longer-lasting way (NIDA, 2021; SAMHSA, 2021). This method ensures that patients remain stable without needing to see and use illicit heroin. However, alcohol dependence does not replace alcohol with other substances; instead, drugs such as naltrexone work to eliminate the cravings and reward effects associated with alcohol (NIAAA, 2024). Meanwhile, the drug acamprosate works to support continued absence of alcohol (NIAAA, 2024). Overall, heroin treatment can include substituting illicit heroin with supervised controlled opioids, whereas alcohol treatment centres on reducing cravings and after-effects of the dependence.

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