What is Naltrexone and Where is it Available?

Naltrexone is a non-addictive medication that can help you cut back on drinking by making alcohol feel less rewarding. After a short period of time taking Naltrexone, many people notice they naturally crave alcohol less and find it easier to stop after just one or two drinks.

By gently blocking the “buzz” that drives you to keep drinking, naltrexone supports moderation without taking away your choice. Over time, it can help you feel more in control of your drinking habits.

How Naltrexone Changes the Brain’s Reward Pathway

When you drink alcohol, your brain releases endorphins. These chemicals activate opioid receptors and increase dopamine levels in the brain’s reward system. This creates the pleasurable feeling associated with drinking. Over time, repeated alcohol use strengthens this neurological pathway, reinforcing the link between alcohol and reward.

This is why cutting down drinking can feel difficult — even when motivation is strong. The brain has learned to expect pleasure.

Naltrexone works by blocking opioid receptors, particularly the mu-opioid receptor involved in alcohol’s rewarding effects. When these receptors are blocked, alcohol produces less reinforcement. You may still feel relaxed, but the strong “reward response” is reduced.

With consistent use before drinking, this leads to a process known as pharmacological extinction. Gradually, the brain weakens its learned association between alcohol and pleasure.

How Long Does Naltrexone Take to Work?

By blocking this response, naltrexone reduces the reinforcement associated with alcohol.

However, this neurological change is gradual rather than immediate.

Because drinking habits are learned behaviours built over time, the brain requires repeated experiences of reduced reward before the association weakens. This process is known as pharmacological extinction.

Some individuals notice early changes within the first 1–2 weeks, such as:

• Feeling satisfied sooner
• Less urge for another drink
• Reduced binge episodes

For others, changes become clearer over:

• 4–6 weeks
• Continued improvement over 3–6 months

Consistency is key. Naltrexone should be taken as prescribed — typically prior to drinking — to allow the reward pathway to weaken progressively.

Importantly, it is not designed as an instant “switch off.” Instead, it works cumulatively, supporting long-term alcohol reduction rather than short-term suppression.

Why Lower Dose Naltrexone Is Used to Start Treatment

When beginning naltrexone for alcohol reduction, treatment often starts at a lower introductory dose before moving to the standard therapeutic dose.

This approach — known as dose titration — is widely used in medicine to help the body adjust gradually to a new medication.

Naltrexone works by blocking opioid receptors in the brain, reducing the rewarding effect of alcohol. While this mechanism is well tolerated by most people, introducing it slowly can help minimise early side effects.

Starting with low-dose naltrexone allows:

• The body to adapt more comfortably
• Reduced likelihood of nausea
• Lower risk of sleep disturbance
• Greater treatment adherence
• Increased patient confidence

After an introductory period, the dose is increased to 25mg, and then for full benefit up to 50mg if clinically appropriate.

This gradual step-up process ensures the neurological effects of naltrexone can begin without overwhelming the system.

Is Naltrexone Safe? Side Effects Explained

Naltrexone has been used in clinical practice for over 30 years and is widely regarded as a safe and well-tolerated medication when prescribed appropriately. Originally developed in the United States and later licensed across multiple countries, it has been studied extensively in alcohol reduction and alcohol dependence treatment.

Because naltrexone is a prescription medication in the UK, clinician assessment is always required before use. This ensures it is suitable based on medical history, liver function, and any concurrent medications.

So, what about side effects?

Most people tolerate naltrexone well, particularly when starting at a lower introductory dose. Where side effects do occur, they are usually mild and temporary as the body adjusts.

Common side effects may include:

• Mild nausea
• Headache
• Fatigue or tiredness
• Sleep disturbance or insomnia
• Gastrointestinal discomfort

Clinically Reviewed & Professionally Dispensed

Evidence – Based Approach

Naltrexone is a well-established medication that has been studied extensively in alcohol-related treatment settings. Clinical research has explored its role in reducing the rewarding effects associated with alcohol consumption and supporting behavioural change over time. Roseway Labs recently published an independent article discussing:

• The science behind naltrexone
• Alcohol reward pathways
• Clinical evidence supporting reduction approaches
• The role of pharmaceutical compounding and personalised dosing

Read the article here: Naltrexone, Compounding and Individualised Approaches to Alcohol Reduction

Important Information

Naltrexone is a prescription-only medicine and is not suitable for everyone.

Treatment is provided only following clinical assessment and may not be appropriate for individuals:

• using opioid medications
• with certain liver conditions
• or with other relevant medical considerations

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Naltrexone FAQs

Further Reading

Naltrexone Wikipedia Entry Evidence about the use of naltrexone and for different ways of using it in the treatment of alcoholism The status of naltrexone in the treatment of alcohol dependence: specific effects on heavy drinking. Naltrexone: a controversial therapy for alcohol dependence.