Comparison
Low-Dose Naltrexone vs Thymosin Alpha-1
Side-by-side of Low-Dose Naltrexone and Thymosin Alpha-1. Every row below is pulled from the compound schema and will update as our data grows. For deeper reads, follow through to each compound page.
Low-Dose Naltrexone
Low dose naltrexone at 1.5 to 4.5 mg, one-tenth the 50 mg addiction dose. Compounded Rx. Small trials in fibromyalgia, Crohn's, Hashimoto's.
Thymosin Alpha-1
Thymosin alpha-1 peptide (Zadaxin, thymalfasin): 28-amino-acid TA1 immunomodulator. Dosing, T-cell effects, hepatitis B and HCV adjunct evidence.
Effects at a glance
Low-Dose Naltrexone
- •Off-label use at 1.5 to 4.5 mg, roughly one-tenth the FDA-approved 50 mg addiction-treatment dose
- •Proposed mechanisms include brief opioid receptor blockade triggering rebound endogenous opioid release, plus TLR4 antagonism
- •Compounded prescription only; insurance rarely covers; cash prices 20 to 80 USD per month
- •Younger 2013 reported ~30% pain reduction in fibromyalgia at 4.5 mg in a small crossover trial
- •Smith 2011 reported endoscopic improvement in active Crohn's disease (n=40 placebo-controlled)
- •Vivid dreams affect 20 to 40% in first 2 weeks; manageable by switching to morning dosing
Thymosin Alpha-1
- •28-amino-acid synthetic peptide identical to thymic-derived immunomodulator
- •Approved in over 35 countries as Zadaxin for hepatitis B, hepatitis C adjunct, and immune support
- •Not FDA approved in US; compounded by 503A/503B pharmacies for off-label immune support
- •Modulates T-cell maturation, NK activity, and Th1 polarization in immunocompromised states
- •Standard label dose: 1.6 mg subcutaneously twice weekly
- •Cleanest safety profile in the peptide class with hundreds of regulated trials behind it
Side-by-side
| Attribute | Low-Dose Naltrexone | Thymosin Alpha-1 |
|---|---|---|
| Category | pharmaceutical | peptide |
| Also known as | LDN, naltrexone (low dose) | Talpha1, Ta1, Zadaxin, Thymalfasin |
| Half-life (hr) ↗ | 4 | 2 |
| Typical dose (mg) ↗ | 4.5 | 1.6 |
| Dosing frequency | once daily, typically at bedtime | 2x weekly |
| Routes | oral | subcutaneous, intramuscular |
| Onset (hr) | 1 | 24 |
| Peak (hr) | 1.5 | 168 |
| Molecular weight | 341.4 | 3108.32 |
| Molecular formula | C20H23NO4 | C129H215N33O55 |
| Mechanism | Brief mu-opioid receptor antagonism proposed to trigger compensatory upregulation of endogenous opioids; secondary TLR4 antagonism on microglia and immune cells contributes to anti-inflammatory effect. | Synthetic peptide modulator of innate and adaptive immunity. Promotes T-cell maturation and CD4/CD8 production, modulates Th1/Th2 balance, stimulates NK cell activity, and modulates TLR2/TLR9 signaling in dendritic cells. |
| Legal status | Off-label compounded prescription (naltrexone is FDA approved for opioid and alcohol use disorder at 50 mg) | Approved in 35+ countries as Zadaxin (hepatitis B, hepatitis C adjunct, immune support); not FDA approved in US; compounded by 503A/503B pharmacies for off-label use; not on WADA Prohibited List |
| WADA status | allowed | unknown |
| DEA / Rx | Rx only (not a controlled substance) | Rx only via international approval or US compounding (no controlled-substance schedule) |
| Pregnancy | Insufficient data; not routinely recommended | Not recommended; insufficient data |
| CAS | 16590-41-3 | 62304-98-7 |
| PubChem CID | 5360515 | 16130571 |
| Wikidata | Q426444 | Q913854 |
Safety profile
Low-Dose Naltrexone
Common side effects
- vivid dreams
- sleep disruption
- headache
- mild GI upset
- fatigue (early)
Contraindications
- concurrent opioid use
- acute hepatitis or liver failure
- opioid dependence
- pregnancy (insufficient data)
Interactions
- opioid analgesics (oxycodone, morphine, codeine): blocks analgesic effect; precipitates withdrawal in dependent users(major)
- tramadol: blocks opioid component of analgesia(major)
- thyroid hormone replacement: may alter dose requirements after immune modulation; monitor TSH(minor)
Thymosin Alpha-1
Common side effects
- mild injection-site irritation (rare)
- transient mild fatigue (rare)
- occasional headache (rare)
Contraindications
- pregnancy
- lactation
- active organ transplant rejection therapy
- systemic immunosuppression for autoimmune disease (relative)
- severe active autoimmune disease (caution)
Interactions
- interferon-alpha: additive immune effect; used clinically in approved combination protocols(minor)
- calcineurin inhibitors (cyclosporine, tacrolimus): theoretical destabilization of immunosuppression; avoid(major)
- antimetabolites (azathioprine, mycophenolate): theoretical destabilization of immunosuppression; avoid(major)
- vaccine administration: may augment vaccine response in elderly or immunocompromised; coordinate with clinician(minor)
Which Should You Take?
Low-Dose Naltrexone and Thymosin Alpha-1 score evenly on the criteria we weight (goal breadth, legal accessibility, evidence depth). The conditionals below should drive the decision more than any aggregate score.
- → If your priority is pain modulation, pick Low-Dose Naltrexone.
- → If your priority is post-training recovery, pick Thymosin Alpha-1.
- → If your priority is antiviral action, pick Thymosin Alpha-1.
Edge case: If you cannot self-administer injections, Low-Dose Naltrexone is the only oral option in this pair.
Default choice: either is defensible. Low-Dose Naltrexone edges out on goal breadth + legal accessibility; Thymosin Alpha-1 is the right call if your priority sits in the goals listed above.
This verdict is generated from each compound's schema (goals, legal status, evidence outcomes, dosing route). It updates automatically as our compound data evolves; the deeper read sits on each individual compound page.
Common questions
What is the difference between Low-Dose Naltrexone and Thymosin Alpha-1?
Low-Dose Naltrexone and Thymosin Alpha-1 differ in category (pharmaceutical vs peptide), mechanism, and typical dosing. See the side-by-side table for full details.
Which has a longer half-life, Low-Dose Naltrexone or Thymosin Alpha-1?
Low-Dose Naltrexone half-life is 4 hours; Thymosin Alpha-1 half-life is 2 hours.
Can you stack Low-Dose Naltrexone with Thymosin Alpha-1?
Stack compatibility depends on mechanism overlap, legal status, and individual response. Check each compound page for specific interactions and contraindications before combining.
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