Naltrexone is a medication primarily prescribed to help individuals manage Alcohol Use Disorder (AUD) and Opioid Use Disorder (OUD). It is non-addictive and works differently from narcotic treatments like methadone or buprenorphine. Since Naltrexone affects brain chemistry, patients often ask about potential changes to their sexual drive. This article explores the biological actions of Naltrexone and the available clinical evidence regarding its effects on libido and sexual function.
Naltrexone’s Mechanism of Action
Naltrexone functions as an opioid receptor antagonist, meaning it binds to opioid receptors in the brain without activating them. It primarily targets the mu-opioid receptors, though it also interacts with kappa and delta receptors. By occupying these sites, Naltrexone competitively blocks the effects of external opioids and the body’s naturally produced opioids, known as endorphins.
In Opioid Use Disorder (OUD), this blockade prevents opioids from producing euphoric and rewarding effects, helping patients maintain abstinence. For AUD, Naltrexone blocks the endorphins released after alcohol consumption, dampening alcohol’s pleasurable properties. The medication is available as a daily oral tablet (typically 50 mg) or as a monthly extended-release injection (Vivitrol).
Opioid Receptors and Sexual Function
The endogenous opioid system targeted by Naltrexone is deeply involved in the brain’s reward circuitry, regulating pleasure, motivation, and sexual response. Endorphins are released during sexual activity and orgasm, contributing to feelings of pleasure and reward. This process is linked to the release of dopamine, the primary neurotransmitter associated with motivation.
Because Naltrexone blocks mu-opioid receptors, it can interfere with this natural reward system. By preventing endorphins from binding, the medication may theoretically dampen the pleasurable sensations and motivation associated with sexual desire. The biological pathways governing addiction reward and sexual pleasure overlap significantly.
Clinical Evidence Regarding Libido Effects
Clinical studies and patient reports indicate that changes in sexual desire are a reported side effect of Naltrexone, though the effect is not universal. Sexual side effects, including decreased libido, delayed orgasm, or erectile dysfunction, are reported in a small percentage of patients, often ranging from 2% to 10%. This reduction in desire is sometimes referred to as hypoactive sexual desire disorder.
The drug’s effect on sexual function is complex and highly dependent on the individual’s pre-existing condition. For patients treated for AUD, resolving substance use often improves overall health and sexual function, potentially offsetting negative medication effects. Conversely, Naltrexone’s interference with the reward pathway can lead to decreased sexual interest, which is why it has been studied to reduce symptoms in compulsive sexual behavior disorder.
The impact on sexual response can be dose-dependent and varies significantly between individuals. For example, some older studies involving healthy men on low doses (25 mg) reported an increase in the number and intensity of orgasms. Overall clinical data suggests that while decreased desire is a recognized side effect, it occurs in a minority of patients and is not always consistent.
Addressing Changes in Sexual Desire
If you experience a reduction in sexual desire or function while taking Naltrexone, communicate this openly with your prescribing physician. Management often begins with discussing the timing of the dose or a possible adjustment to the medication strength. Your doctor may adjust the daily dose or switch the formulation, such as moving from the oral pill to the monthly extended-release injection.
It is imperative that you do not stop taking Naltrexone suddenly without professional medical guidance. Discontinuing the medication on your own, especially when treating a substance use disorder, carries a significant risk of relapse. If dose adjustments are not effective, your healthcare provider can explore alternative medications or discuss supportive treatments to manage the sexual side effects.