Naltrexone is primarily prescribed to manage alcohol use disorder and opioid use disorder by reducing cravings and blocking the euphoric effects of these substances. As an opioid blocker, people often question its effects on the body’s internal systems, particularly energy levels. Whether naltrexone increases energy is complex, depending heavily on the dosage and the patient’s underlying health condition. The medication can have vastly different effects on energy depending on the context of its use.
How Naltrexone Interacts with the Body
Naltrexone functions as an opioid receptor antagonist, binding to receptors in the brain, most notably the mu-opioid receptor, without activating them. This action effectively blocks the effects of both external opioids and the body’s own naturally produced opioids, known as endorphins. By occupying these receptor sites, naltrexone prevents substances from attaching and producing effects like pain relief or euphoria.
This blockage is the central mechanism by which naltrexone helps reduce cravings for alcohol and opioids. The medication also interacts with the hypothalamic-pituitary-adrenal (HPA) axis, the body’s central stress response system. By interfering with natural opioid signaling, naltrexone modifies various physiological processes, which helps explain its impact on energy, mood, and pain perception.
Energy Effects of Standard Dose Naltrexone
The standard oral dose of naltrexone, typically 50 milligrams (mg) once daily, is primarily used for managing substance use disorders. At this dosage, the medication does not act as a pharmacological stimulant and is not intended to provide an immediate energy boost. Instead, the initial experience for many patients can include side effects that temporarily reduce perceived energy.
Common initial side effects include fatigue, dizziness, and general malaise. Patients may also experience sleep disturbances, such as insomnia or nervousness, which can lead to daytime tiredness. These effects are often transient, tending to diminish within a few days or weeks as the body adjusts.
Any sustained improvement in energy levels while on the standard dose is generally considered an indirect benefit. As the medication helps patients maintain abstinence, the body stabilizes and recovers from the physical and mental stress of substance use. This normalization of physiological function, rather than the drug itself, ultimately leads to an increase in long-term, stable energy.
Low Dose Naltrexone and Perceived Energy Changes
A distinct therapeutic approach involves using naltrexone at much lower doses, known as Low Dose Naltrexone (LDN), typically ranging from 1.5 mg to 4.5 mg per day. This application is considered off-label, used for conditions like chronic pain and certain autoimmune disorders. LDN is frequently utilized for conditions such as fibromyalgia and chronic fatigue syndrome, which are characterized by persistent exhaustion.
The proposed mechanism of LDN differs from the standard dose, focusing on immune system modulation and a temporary increase in endorphin levels. By briefly blocking opioid receptors, LDN may prompt the body to increase its production of natural endorphins, which can alleviate pain and improve mood. This transient blockade also appears to modulate the activity of glial cells in the central nervous system, which are involved in neuro-inflammation.
Since chronic inflammation is often linked to persistent fatigue, the anti-inflammatory effects of LDN are thought to be responsible for reported improvements in energy and quality of life for specific patient populations. The positive energy changes associated with LDN are condition-specific, usually seen in people whose fatigue is rooted in inflammatory or autoimmune processes. This effect is not a direct, stimulant-like boost but rather a reduction in the underlying causes of chronic exhaustion.
Indirect Factors Affecting Energy Levels
Beyond the direct pharmacological effects, several common side effects of naltrexone can indirectly influence perceived energy. A frequent initial complaint is trouble sleeping, including difficulty falling asleep or experiencing vivid dreams. This poor sleep quality naturally results in increased fatigue and a lack of refreshment during the day.
Naltrexone can also cause changes in mood, such as increased anxiety, nervousness, or irritability, especially during the initial adjustment period. Managing these shifts in mental state requires psychological effort, which can be perceived as an overall draining of energy. For some, common mild side effects like nausea or headache contribute to a feeling of being unwell, further diminishing vitality.