Naltrexone (LDN)

Capsule

1.5 mg  |  3 mg  |  4.5 mg

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Product Overview

Naltrexone (LDN) Description1-5

Low Dose Naltrexone (LDN) refers to naltrexone hydrochloride administered in doses ranging from 0.5 mg to 4.5 mg, which is substantially lower than the standard 50–100 mg doses used for opioid or alcohol dependence. At these lower doses, naltrexone may have immunomodulatory and anti-inflammatory effects and can be compounded into capsules.

Under the supervision of a healthcare provider, LDN may be considered as an adjunct for conditions such as:

  • Autoimmune diseases (e.g., multiple sclerosis, Hashimoto’s thyroiditis, rheumatoid arthritis)
  • Chronic pain syndromes (e.g., fibromyalgia, complex regional pain syndrome)
  • Inflammatory disorders (e.g., Crohn’s disease)

Mechanism of Action1-5

There are several potential pathways that may explain the activity of low-dose naltrexone, although further studies are needed to fully understand the mechanism of action. The following are potential pathways of activity:

  1. Opioid Receptor Modulation

LDN may temporarily block opioid receptors (especially μ-opioid receptors) for a few hours.

This transient blockade can lead to a rebound increase in endogenous endorphins and enkephalins when the drug is cleared.

Higher levels of endorphins may enhance immune system regulation and reduce pain perception.

  1. Toll-Like Receptor 4 (TLR4) Antagonism

Naltrexone acts as a non-specific antagonist of TLR4, found on microglia in the CNS.

By inhibiting TLR4, LDN reduces the release of pro-inflammatory cytokines (e.g., TNF-α, IL-6).

This may help to reduce neuroinflammation, often implicated in chronic pain and autoimmune disorders.

  1. Immunomodulation

LDN is thought to restore T-regulatory cell function and normalize Th1/Th2 balance, critical in autoimmune disease regulation.

May inhibit abnormal B-cell activity and reduce autoantibody production.

Common1-5

  • Vivid dreams or insomnia (often resolves after 1–2 weeks)
  • Headache
  • Nausea
  • Fatigue
  • Anxiety or restlessness

Contraindications1-5

  • Current opioid use: LDN may precipitate opioid withdrawal and block opioid analgesia.
  • Known hypersensitivity to naltrexone hydrochloride or its excipients.

Precautions1-5

  • Liver disease: Though rare at low doses, monitor liver function if using long term or in patients with hepatic impairment.
  • Autoimmune flare risk: Temporary symptom worsening may occur during immune modulation.
  • Use caution in:
  • Patients with major depressive disorder (monitor mood)
  • Pregnant or lactating individuals (safety not well established)
  • Store at controlled room temperature (20°C to 25°C / 68°F to 77°F)
  • Protect from moisture and light
  • Keep in a tightly closed container
  1. Younger J, Noor N, McCue R, Mackey S. “Low-dose naltrexone for the treatment of fibromyalgia: findings of a small, randomized, double-blind, placebo-controlled, counterbalanced, crossover trial.” Arthritis Rheum. 2013;65(2):529-538. https://pubmed.ncbi.nlm.nih.gov/23359310/
  2. Smith JP, Stock H, et al.“Low-dose naltrexone therapy improves active Crohn’s disease.”Am J Gastroenterol. 2007;102(4):820–828. https://pubmed.ncbi.nlm.nih.gov/17222320/
  3. Brown N, Panksepp J.“Low-dose naltrexone for disease prevention and quality of life.”Med Hypotheses. 2009;72(3):333–337. https://pubmed.ncbi.nlm.nih.gov/19041189/
  4. LDN Research Trust (non-profit organization with compiled clinical data and patient reports): accessed August 2025 through: https://www.ldnresearchtrust.org
  5. U.S. National Library of Medicine – DailyMed (Naltrexone HCl official monograph) accessed August 2025 through: https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=06ff2d5a-e62b-4fa4-bbdb-01938535bc65

WPPL operates as a 503A compounding pharmacy and prepares individualized prescription medications pursuant to provider direction. Compounded preparations are not reviewed, tested, or approved by the FDA.

This listing also includes commercially manufactured products for convenience; these items are not compounded by our pharmacy and are sold as provided by their manufacturers. Actual products in stock at time of dispensing may vary due to supply chain variability. Any statements regarding non-compounded products are manufacturer-supplied, have not been evaluated by the FDA, and are not intended to diagnose, treat, cure, or prevent any disease. WPPL does not verify or endorse any therapeutic claims made by manufacturers. Please refer to original labeling for complete product information.

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