Low-Dose Naltrexone (LDN)

Oral capsule (1.5mg / 3mg / 4.5mg, typically at bedtime)Available in all 50 states

Marketing purposes only. Actual medications, if prescribed, are dispensed by a licensed pharmacy.

other

Low-Dose Naltrexone (LDN)Low-Dose Naltrexone (LDN)

At 1.5 to 4.5mg, about 1/10th of the addiction-medicine dose, naltrexone acts as a transient opioid-receptor antagonist and TLR4 modulator. It's studied off-label for autoimmune disease, chronic pain, and neuroinflammatory conditions.

TLR4 antagonism, reduced microglial neuroinflammation

Transient opioid blockade upregulates endogenous endorphins

Considered for autoimmune flares, fibromyalgia, IBD, MS, Hashimoto's

Once-daily oral dosing; well-tolerated long-term

No commitment · HSA/FSA eligibleNo commitment · HSA/FSA eligible

How it works

Mechanism of action

At low doses, naltrexone briefly blocks opioid receptors overnight, triggering a compensatory rise in endogenous endorphins and enkephalins. This rebound is hypothesized to modulate immune cell function via opioid growth factor receptor (OGFr) signaling.

Naltrexone is also a Toll-like receptor 4 (TLR4) antagonist on microglia and peripheral immune cells. Suppressing TLR4-driven inflammation may explain the reductions in pain, fatigue, and disease activity reported across multiple autoimmune indications in published trials.

The baseline panel.

Every Marek client receives this baseline panel before a provider review. Your provider may add additional biomarkers based on your health history, symptoms, and goals, pulling from 1,000+ available markers. See more biomarkers →

Hormone Profile

12 markers

Sex hormones

Total TestosteroneLC/MS
Free TestosteroneEquilibrium Dialysis
Estradiol, Sensitive / UltrasensitiveLC/MS
Sex Hormone Binding Globulin (SHBG)
ProgesteroneLC/MSFemale panel
Prolactin
Luteinizing Hormone (LH)
Follicle-Stimulating Hormone (FSH)
hCG, Total, QuantitativeFemale panel, pre-menopause

Adrenals & neurosteroids

Cortisol
DHEA-S

Growth hormone / IGF-1

Insulin-Like Growth Factor I (IGF-1)

Thyroid Status

3 markers

Thyroid hormones

Thyroid Stimulating Hormone (TSH)
Free T4
Free T3

Heart Health

9 markers

Cardiovascular health

Total Cholesterol
HDL Cholesterol
LDL Cholesterol
LDL:HDL Ratio
VLDL Cholesterol
Triglycerides
Apolipoprotein-B (ApoB)
C-Reactive Protein, High Sensitivity (hsCRP)
Lipoprotein(a) (Lp(a))

Metabolism

3 markers

Insulin sensitivity

Blood Glucose
Fasting Insulin
HbA1c

Organ Function

26 markers

Liver & pancreas

AST
ALT
Bilirubin, Total
γ-Glutamyl Transferase (GGT)

Kidney function

BUN
Creatinine w/ eGFR

Comprehensive Metabolic Panel (CMP)

Glucose
Blood Urea Nitrogen (BUN)
Creatinine
eGFR
BUN/Creatinine Ratio
Sodium
Potassium
Chloride
Carbon Dioxide, Total
Calcium
Protein, Total
Albumin
Globulin, Total
Albumin/Globulin (A/G) Ratio
Alkaline Phosphatase (ALP)
AST
ALT

Prostate health

Prostate-Specific Antigen (PSA)Male panel
Free PSAMale panel
% Free PSAMale panel

Nutrient Status

31 markers

Vitamins & minerals

Vitamin D, 25-OHD (25-Hydroxy)
Magnesium, RBC

Iron status

Iron
Iron Saturation
TIBC
UIBC
Ferritin

Complete Blood Count (CBC)

White Blood Count (WBC)
Red Blood Count (RBC)
Hemoglobin (Hgb)
Hematocrit (HCT)
MCV
MCH
MCHC
Red Cell Distribution Width (RDW)
Platelets
Neutrophils
Neutrophils (Absolute)
Lymphocytes
Lymphocytes (Absolute)
Neutrophil/Lymphocyte Ratio
Monocytes
Monocytes (Absolute)
Eosinophils
Eosinophils (Absolute)
Basophils
Basophils (Absolute)
Immature Cells
Immature Granulocytes
Immature Granulocytes (Absolute)
NRBC, w/ Reflex for Immature Cells

Clinical evidence

The research behind Low-Dose Naltrexone (LDN).

Low-dose naltrexone for fibromyalgia: a randomized, double-blind, crossover trial

Pain Medicine (2013)

30 women with fibromyalgia. LDN was associated with significant reductions in pain compared with placebo; treatment was well-tolerated with minimal side effects.

Read study →

Low-dose naltrexone in Crohn's disease: randomized placebo-controlled trial

American Journal of Gastroenterology (2007)

17 patients with active Crohn's. LDN was associated with significant improvement in CDAI scores; 67% of treated patients achieved remission versus none on placebo.

Read study →

Safety profile

Monitoring & safety information.

Commonly reported side effects

Vivid dreams (especially during initiation)
Insomnia (typically transient)
Mild GI upset
Headache

Less common but serious risks

Acute opioid withdrawal if combined with opioid analgesics
Rare hepatotoxicity (more typical at addiction-medicine doses)

Generally not appropriate for

Concurrent opioid use (prescription or recreational)
Acute hepatitis or severe liver disease
Pregnancy / breastfeeding (insufficient data)
Known hypersensitivity to naltrexone

Typical monitoring

Liver function (LFTs)
Symptom and quality-of-life assessment
CRP / hsCRP and condition-specific inflammatory markers
Concurrent medication review

FAQ

Quick answers.

Eligibility, dose, and duration are determined by a partnered licensed medical provider based on your complete labs and medical history. A prescription is not guaranteed, your provider may recommend LDN, a different therapy, or further evaluation.

LDN is naltrexone prescribed at 1.5 to 4.5mg, a tenth of the addiction-medicine dose. It's used off-label for autoimmune disease, chronic pain, and neuroinflammation, with two proposed mechanisms: transient opioid receptor blockade and TLR4 antagonism.

Most people who respond to LDN do so within 1 to 3 months of consistent use, though some report improvement sooner. If there is no response by 4 to 6 months, your provider may consider dose adjustment or an alternative.

The most common side effects are vivid dreams and transient insomnia, which usually resolve as the body adjusts. Mild GI upset and headache are also reported. Serious risks are rare at low doses but include acute withdrawal if combined with opioids.

View all FAQs

See all FAQs

Treatments are dependent on licensed clinical prescription. Client costs vary based on individual labs and panel in treatments and services.