Naltrexone 4.5mg

Oral capsule: Swallow intact once daily at bedtime. Bedtime administration aligns with the peak physiologic endorphin surge (approximately 2–4 AM), allowing the rebound endorphin effect after the brief 3–4 hour receptor blockade to coincide with natural endorphin rhythms. Swallow with water with or without food. Do not crush or open the capsule. Consistency of administration timing is important for the proposed mechanism of action.

All dosing is prescriber-determined. 4.5 mg is the most commonly prescribed full LDN dose.

• Initiation: Prescribers often begin at a lower dose (0.5–1.5 mg/day) and titrate upward by 0.5–1.5 mg increments every 2–4 weeks to allow tolerability assessment and immune system adjustment.
• Maintenance: 4.5 mg once daily at bedtime for most indications; some protocols use 3 mg (particularly for multiple sclerosis).
• Hashimoto's thyroiditis: Typical doses 3–4.5 mg — monitor for rapid changes in thyroid antibody levels and thyroid function.
• Dosing should be interrupted around chemotherapy administration (if applicable) per prescriber guidance.

• Naltrexone 4.5 mg (LDN): At low doses, naltrexone transiently occupies opioid receptors (μ, δ, κ) for 3–4 hours, then is cleared. This brief blockade signals the body to increase endogenous endorphin and enkephalin production (the rebound effect), and to upregulate opioid receptor density and sensitivity. The elevated endorphins persist for 18–20 hours, interacting with opioid receptors throughout the immune system — downregulating pro-inflammatory cytokines (TNF-α, IL-6, IL-12), enhancing cytotoxic T-cell and NK-cell activity, and restoring Th1/Th2 immune balance. Additionally, naltrexone at low doses has been shown to antagonize toll-like receptor 4 (TLR4) — an innate immunity receptor involved in neuroinflammation — and TLR9, reducing microglial activation in the CNS and decreasing neuroinflammatory signaling relevant to conditions like multiple sclerosis and fibromyalgia.

Investigated off-label indications (not FDA-approved): Multiple sclerosis, fibromyalgia, Crohn's disease, Hashimoto's thyroiditis, rheumatoid arthritis, lupus, chronic fatigue syndrome (ME/CFS), psoriasis, and various autoimmune and neuroinflammatory conditions. Small clinical trials have demonstrated benefits in multiple sclerosis (spasticity, pain) and Crohn's disease; evidence for other indications is mostly observational or case-based.

Prescriber monitoring:

• Baseline and periodic liver function tests — hepatotoxicity has been observed at very high naltrexone doses (not at 4.5 mg, but surveillance is appropriate)
• In Hashimoto's: monitor thyroid function every 6–8 weeks — LDN may substantially reduce antibody titers, requiring adjustment of thyroid hormone replacement dose
• In MS: assess spasticity and pain scores; monitor for sleep disturbances (particularly in first 2–4 weeks of therapy)
• Do not administer concurrent opioid analgesics — LDN will precipitate withdrawal and block analgesic effects

Contraindications:

• Concurrent use of opioid analgesics (any opioid) — naltrexone will displace opioids from receptors and precipitate acute withdrawal
• Current physiologic opioid dependence
• Hepatic failure (use with caution; severe liver disease is a relative contraindication)
• Hypersensitivity to naltrexone or any excipient

Warnings & Precautions:

• Patients must be opioid-free for a minimum of 7–10 days before initiating LDN to avoid precipitating withdrawal
• Sleep disturbances (vivid dreams, insomnia) are common at initiation — typically resolve within 4–6 weeks
• LDN may interfere with cancer chemotherapy regimens — consult with oncology before prescribing; typically held 2 days before and 2 days after chemotherapy administration
• Organ transplant patients on immunosuppressants — potential immune-modulating interactions

Drug Interactions:

• All opioids: antagonized effects and potential precipitated withdrawal — absolute contraindication during concurrent use
• Immunosuppressants: theoretical immune-modulating interaction — use with caution in transplant patients

Common Side Effects: Vivid dreams, insomnia (particularly in first 2–4 weeks of therapy), mild nausea, headache, and fatigue at initiation. These are generally transient and self-resolving.

Store at room temperature (20–25°C), away from moisture, heat, and light. Keep tightly capped in the original dispensing container. Do not store in bathroom medicine cabinets. Observe the beyond-use date assigned by Genesis Compounding. Keep out of reach of children and pets.

Why is this only 4.5 mg when naltrexone is usually prescribed at 50 mg?

At 50 mg, naltrexone fully saturates opioid receptors for 24 hours — appropriate for blocking euphoric effects in substance use disorder. At 4.5 mg, it briefly blocks receptors for only 3–4 hours, triggering the body to increase its own endorphin production and upregulate receptor sensitivity — a completely different mechanism that provides immune-modulating and anti-inflammatory effects rather than receptor blockade.

Can I take pain medication while on LDN?

No. Naltrexone at any dose will block opioid pain medications and precipitate withdrawal if opioids are present in your system. If you require an opioid for acute pain, LDN must be discontinued at least 24 hours before and should not be restarted until the opioid has been cleared from your system. Always inform all treating clinicians that you are on naltrexone.

How long does LDN take to work?

Most patients require 4–12 weeks of consistent use before noticing significant improvements in their condition. Some patients experience initial worsening of sleep or mild nausea in the first 2–4 weeks, which typically resolves. Benefit may not be fully apparent for 3–6 months.

Is this FDA-approved?

Naltrexone is FDA-approved at 50 mg for opioid and alcohol use disorder. Low-dose naltrexone at 4.5 mg is not FDA-approved for any indication. This is a prescriber-directed, patient-specific 503A compounded preparation by Genesis Compounding.

Why should I take this at bedtime?

Taking LDN at bedtime aligns the rebound endorphin surge (which occurs approximately 4–6 hours after the dose) with the natural peak of endorphin production in the early morning hours (approximately 2–4 AM), potentially maximizing the immune-modulating effect.