Low-Dose Naltrexone: Compounded vs Branded Comparison

There is no branded low-dose naltrexone to compare against

Naltrexone is FDA-approved as two single-drug products and one combination product, and none of them is a low-dose product.

The oral tablet carries 50 mg. Revia (NDA 018932) was approved on 20 November 1984 and is now marked discontinued, with generics approved in its place [2]. The tablets are indicated for alcohol dependence and for blockade of the effects of exogenously administered opioids, and the label states they have not been shown to provide any therapeutic benefit except as part of an appropriate plan of management for the addictions [1].

Vivitrol is naltrexone 380 mg for extended-release intramuscular injection (NDA 021897, approved 13 April 2006 as a new dosage form), given as a deep gluteal injection every 4 weeks [3][13]. It is indicated for alcohol dependence in patients able to abstain in an outpatient setting before starting, who should not be actively drinking at the first injection, and for prevention of relapse to opioid dependence following detoxification [3].

Contrave is the third product: naltrexone plus bupropion for weight management, approved 10 September 2014, with a boxed warning for suicidal thoughts and behaviors from the bupropion component and a label note that coadministration with other naltrexone-containing products is not recommended [4]. It is not LDN.

No FDA-approved low-dose naltrexone product contains 4.5 mg or carries a low-dose indication; LDN is an off-label compounded use [5][6].

Why low-dose naltrexone is usually compounded

LDN means naltrexone at doses far below the approved 50 mg tablet, typically 0.5 to 6 mg a day and most often 4.5 mg, used off-label for conditions such as fibromyalgia, multiple sclerosis, Crohn's disease and long COVID, and supplied mainly through compounding pharmacies [5][10]. A 2026 narrative review describes the 4.5 mg dose as 'empirically derived rather than evidence-based' [5].

FDA describes a proper use of compounding as a patient who cannot be treated with an approved drug, such as someone with an allergy to a dye who needs a medicine made without it, or a child or older adult who cannot swallow a tablet and needs a liquid. The same page says compounded drugs should only be used in patients whose medical needs cannot be met by an FDA-approved drug, that compounded drugs are not FDA-approved, that FDA does not verify their safety, effectiveness or quality before they are marketed, and that poor compounding practices can produce contamination or a product with too much or too little active ingredient [6].

Naltrexone itself is not on FDA's list of bulk drug substances for compounding that may present significant safety risks [14]. The 2026 review also notes that inconsistencies in compounded formulations add uncertainty [5].

Side by side

Is one type of LDN better than another?

The LDN trials described below compared LDN with placebo, so they do not show whether one LDN preparation performs differently from another. Compounding can supply low-dose capsules or liquids that are not sold as approved products [5][6].

What the trials measured

Fibromyalgia

The first small trial set the pattern. Ten women took part in a single-blind crossover pilot, and the report described a greater than 30% reduction of symptoms over placebo with 4.5 mg daily [15]. A larger crossover followed: 31 women, 4.5 mg daily versus placebo, with pain falling 28.8% on naltrexone versus 18.0% on placebo (P=0.016) and 32% versus 11% meeting a responder definition (P=0.05); fatigue and sleep did not improve [11].

The later, larger placebo-controlled trials were negative on their main pain outcomes. A 2023 crossover of 58 patients testing 4.5 mg found a median difference in FIQR score of -1.65 (P=0.3) and in summed pain ratings of -0.33 (P=0.4), and the authors concluded the data did not indicate clinically relevant analgesic efficacy [8]. A 2024 trial of 99 women testing 6 mg found pain intensity change of -1.3 with naltrexone versus -0.9 with placebo, a between-group difference of -0.34 points (95% CI -0.95 to 0.27, p=0.27) [7]. The 12-month INNOVA trial of 98 women testing 4.5 mg found pain change at 3 months of -0.33 with naltrexone versus -0.64 with placebo, an adjusted difference of 0.49 (p=0.236), with adverse events in 68.8% versus 72% [9].

A 2024 meta-analysis of four randomized trials (222 patients) found lower pain scores with LDN, mean difference -0.86 (95% CI -1.20 to -0.51), but no significant difference in the revised fibromyalgia impact questionnaire, and more vivid dreams and nausea with LDN [16].

Crohn's disease

A randomized double-blind trial enrolled 40 adults with active Crohn's disease and gave 4.5 mg daily or placebo for 12 weeks [17]. A fall of 70 points or more on the Crohn's Disease Activity Index occurred in 88% versus 40% (p=0.009), and endoscopic response in 78% versus 28% (p=0.008) [17]. This is a small single trial. A 2018 Cochrane review located two randomized trials with 46 participants in total: the 12-week adult trial and an 8-week trial in 12 children at 0.1 mg/kg up to a maximum of 4.5 mg daily [18].

Multiple sclerosis

A single-center pilot tested 4.5 mg nightly for 8 weeks in a placebo-controlled crossover. Eighty people enrolled and 60 completed; LDN improved the SF-36 Mental Component Summary by 3.3 points (p=0.04) and the Mental Health Inventory by 6 points (p<0.01), and the authors reported that a high dropout rate and data management errors substantially reduced statistical power [19].

Safety considerations differ by formulation

Naltrexone's opioid-related warnings apply across this comparison, while Vivitrol has injection-site risks and compounded products carry quality uncertainties [1][3][6].

Naltrexone is a pure opioid antagonist, and the label says it is not associated with tolerance or dependence [1]. The labels contraindicate it in patients receiving opioid analgesics, in patients currently dependent on opioids including those maintained on methadone or buprenorphine, in patients in acute opioid withdrawal, in anyone who has failed a naloxone challenge or has a positive urine screen for opioids, and in anyone with a history of hypersensitivity to naltrexone or the product's components [1][3]. The opioid-analgesic contraindication is written without any dose exception [1].

To reduce the risk of precipitated withdrawal, the tablet label says opioid-dependent patients, including those being treated for alcohol dependence, should be opioid-free (including tramadol) before starting, with a minimum of 7 to 10 days recommended for short-acting opioids; it adds that patients transitioning from buprenorphine or methadone may remain vulnerable to precipitated withdrawal for as long as 2 weeks [1]. The Vivitrol label likewise recommends at least 7 to 10 opioid-free days [3]. In the tablet label, withdrawal symptoms usually appeared within 5 minutes of ingestion and lasted up to 48 hours, and postmarketing cases required hospital admission and sometimes intensive care [1].

The labels say opioid tolerance is lower after treatment stops, at the end of a dosing interval and after a missed dose, so a previously tolerated opioid dose can cause fatal overdose; fatal overdoses have been reported, and the labels advise strongly considering an opioid overdose reversal agent such as naloxone or nalmefene at initiation and renewal [1][3].

Hepatitis and clinically significant liver dysfunction were seen in development and postmarketing, and placebo-controlled studies at up to 300 mg a day, five times the recommended dose, showed hepatocellular injury in a substantial proportion of patients [1]. Depression, suicidal ideation and suicide attempts have been reported after marketing, and the tablet label says no causal relationship has been demonstrated [1].

For LDN specifically, the 2026 review reports that trials mostly saw mild, transient effects, most often insomnia, vivid dreams, nausea and dizziness, and that safety data in pregnancy and in liver or kidney impairment are sparse [5].

Who oversees compounded products

FDA says state boards of pharmacy generally have primary responsibility for day-to-day oversight of state-licensed pharmacies, while facilities registered with FDA as outsourcing facilities are inspected by FDA on a risk-based schedule and are subject to current good manufacturing practice requirements [6]. FDA also notes that people who buy compounded drugs online may not know which compounder produced the product [6].

Bottom line

The comparison the page title implies does not exist: there is no branded LDN. The choice is between a compounded low-dose product, which is not FDA-approved, and approved naltrexone at 50 mg or as a 380 mg injection, which was studied and labeled for alcohol dependence and opioid blockade rather than for low-dose off-label use [1][3][5][6]. The approved-product labels warn about opioid use, precipitated withdrawal, overdose and liver injury, and they give no guidance for LDN doses [1][3][5].