Introduction
Some of the most exciting developments in integrative medicine involve drugs that have been used safely for decades — but for entirely different purposes than the ones now being researched. Low dose naltrexone was developed for opioid addiction. Ivermectin was developed for parasitic infections. Fenbendazole is a veterinary dewormer. Niclosamide was used to treat tapeworms. DMSO was originally an industrial solvent.
Yet each of these agents has demonstrated remarkable therapeutic potential across a range of chronic diseases — from autoimmune conditions and neurological disorders to metabolic disease and cancer — through mechanisms that have nothing to do with their original indications. This phenomenon is called drug repurposing (or drug repositioning), and it represents one of the most promising and cost-effective frontiers in modern medicine.
This article explains, in plain language, what each of these agents is, how it works, what the evidence shows, and how people access them. For condition-specific guidance on how these agents are used in integrative protocols, see our Specific Diseases & Ailments education hub.
Important: This article is for educational purposes only. All pharmaceutical agents discussed here should only be used under the supervision of a qualified healthcare provider. See our Educational Standards & Medical Disclaimer for full details.
What Is Drug Repurposing?
Drug repurposing refers to the use of an existing, approved pharmaceutical agent for a new therapeutic indication — one different from its original FDA-approved use. This is also called "off-label" use when a licensed physician prescribes an approved drug for a non-approved indication.
Off-label prescribing is entirely legal, common, and often evidence-based. Approximately 20% of all prescriptions written in the United States are for off-label uses. Many of the most important medical advances — aspirin for cardiovascular disease, metformin for PCOS, beta-blockers for heart failure — began as off-label observations before becoming standard of care.
The appeal of repurposed drugs is significant: they have established safety profiles from years or decades of use, known pharmacokinetics, existing manufacturing infrastructure, and dramatically lower costs than novel pharmaceuticals. The primary barrier is not safety or efficacy — it is the absence of patent protection, which reduces pharmaceutical industry incentive to fund the large clinical trials required for new FDA indications.
Low Dose Naltrexone (LDN)
What Is Naltrexone?
Naltrexone is an FDA-approved opioid receptor antagonist — it blocks opioid receptors and is used at standard doses (50mg/day) to treat opioid use disorder and alcohol dependence. It has been approved and used safely since 1984.
What Makes Low Dose Naltrexone Different?
At very low doses — typically 1.5 to 4.5mg per day, roughly 1/10th of the standard dose — naltrexone produces entirely different effects through different mechanisms. This is the basis of Low Dose Naltrexone (LDN).
How LDN Works
LDN’s therapeutic mechanisms at low doses include:
- Transient opioid receptor blockade → endorphin rebound — LDN briefly blocks opioid receptors for a few hours (typically taken at bedtime), causing the body to compensate by producing more endorphins and upregulating opioid receptors. This endorphin surge has immune-modulating, anti-inflammatory, and mood-enhancing effects that persist throughout the day.
- TLR4 antagonism — LDN blocks Toll-like receptor 4 (TLR4) on microglia (the brain’s immune cells) and macrophages, directly suppressing neuroinflammation and systemic inflammatory cytokine production (TNF-α, IL-6, IL-1β). This is its primary anti-inflammatory mechanism.
- OGF/OGFr axis modulation — LDN transiently blocks the opioid growth factor receptor (OGFr), triggering upregulation of endogenous opioid growth factor (met-enkephalin), which has direct anti-proliferative effects on cancer cells and immune-modulating effects.
What Conditions Is LDN Used For?
LDN has clinical evidence or strong mechanistic rationale across a wide range of conditions including autoimmune diseases (MS, Crohn’s, rheumatoid arthritis, lupus), fibromyalgia and chronic pain, depression, anxiety, and neurodegeneration, cancer support, Long COVID and post-infectious conditions, and metabolic and inflammatory disease.
Safety Profile
LDN has an excellent safety profile. The most common side effect is vivid dreams or mild sleep disturbance when first starting, which typically resolves within 1–2 weeks. It does not cause opioid dependence at low doses. It cannot be used by individuals taking opioid medications (it will precipitate withdrawal) or those with certain liver conditions.
How to Access LDN
LDN requires a prescription from a licensed physician. Because it is not FDA-approved for the conditions it is most commonly used for, it must be prescribed off-label. Compounding pharmacies prepare LDN in the required low doses (standard naltrexone tablets are 50mg and cannot simply be split). Many functional medicine physicians, naturopathic doctors, and integrative practitioners are familiar with LDN. Online telehealth platforms specializing in LDN prescribing have also made access significantly easier.
Ivermectin
What Is Ivermectin?
Ivermectin is an FDA-approved antiparasitic agent used in humans since 1987 for conditions including river blindness (onchocerciasis), strongyloidiasis, scabies, and head lice. It has been administered over 4 billion times globally and has an exceptional safety record. It won the Nobel Prize in Physiology or Medicine in 2015 for its transformative impact on tropical infectious diseases.
How Ivermectin Works (Beyond Antiparasitic)
Ivermectin’s repurposing potential stems from mechanisms entirely separate from its antiparasitic action:
- Antiviral — inhibits importin α/β-mediated nuclear transport, blocking viral replication machinery used by a broad range of RNA and DNA viruses
- NF-κB inhibition — reduces the master inflammatory transcription factor driving cytokine production across virtually all inflammatory conditions
- NLRP3 inflammasome suppression — reduces IL-1β and IL-18 production; relevant in metabolic disease, gout, neurodegeneration, and cancer
- PAK1 inhibition — blocks a kinase central to cancer cell proliferation, metastasis, and immune evasion
- P-glycoprotein inhibition — reverses multidrug resistance in chemotherapy-resistant cancers
- WNT-TCF pathway inhibition — reduces cancer stem cell activity
- Immune modulation — enhances NK cell and cytotoxic T-cell anti-tumor activity
Safety Profile
At standard antiparasitic doses, ivermectin is extremely well-tolerated. Side effects are typically mild and transient (dizziness, nausea, mild rash). It should not be used in pregnancy (first trimester), in individuals with certain neurological conditions affecting the blood-brain barrier, or alongside certain medications (warfarin, some antiretrovirals). Higher doses used in some repurposing protocols require medical supervision.
How to Access Ivermectin
Ivermectin is FDA-approved and available by prescription. Off-label prescribing by a licensed physician is legal. Compounding pharmacies can prepare specific doses. Telehealth platforms specializing in integrative medicine can facilitate prescriptions where clinically appropriate.
Fenbendazole & Mebendazole
What Are They?
Fenbendazole is a benzimidazole anthelmintic (dewormer) used in veterinary medicine. Mebendazole is its close chemical cousin — FDA-approved for human use to treat intestinal parasites (pinworm, roundworm, hookworm, whipworm). Both belong to the benzimidazole drug class, which also includes albendazole (another human-approved antiparasitic).
How Benzimidazoles Work Against Cancer & Chronic Disease
The repurposing interest in fenbendazole and mebendazole stems from their ability to inhibit tubulin polymerization — the same mechanism used by taxane and vinca alkaloid chemotherapy drugs, but at much lower toxicity. Their anti-cancer and anti-inflammatory mechanisms include:
- Tubulin polymerization inhibition — disrupts mitotic spindle formation, arresting cancer cell division
- Glucose transporter (GLUT) downregulation — reduces glucose uptake by cancer cells, directly targeting the Warburg effect (cancer’s dependence on glucose fermentation)
- Hexokinase II inhibition — blocks the first step of glycolysis in cancer cells
- p53 activation — restores tumor suppressor function
- Bcl-2 inhibition — promotes apoptosis (programmed cancer cell death)
- VEGF suppression — anti-angiogenic; starves tumors of blood supply
- Wnt/β-catenin inhibition — reduces cancer stem cell self-renewal
- HIF-1α inhibition — reduces hypoxia-driven tumor adaptation
The "Joe Tippens Protocol" — combining fenbendazole with vitamin E succinate, curcumin, and CBD — generated significant public interest following documented cases of advanced cancer remission and has been the subject of ongoing research interest.
Fenbendazole vs. Mebendazole
Mebendazole is FDA-approved for human use and has a more established human pharmacokinetic profile. Fenbendazole is not FDA-approved for humans but is widely available as a veterinary product. Both have been used in human repurposing protocols; mebendazole is generally preferred when medical supervision is involved due to its established human safety data.
Safety Profile
Mebendazole has an excellent safety profile at antiparasitic doses with minimal systemic absorption. At higher doses used in some repurposing protocols, liver enzyme monitoring is recommended. Fenbendazole has a similarly favorable safety profile based on veterinary use and human case reports, but formal human safety data is more limited.
How to Access
Mebendazole is available by prescription (off-label for repurposing applications). Fenbendazole is available over-the-counter as a veterinary product (e.g., Panacur C). Medical supervision is strongly recommended for any repurposing application.
Niclosamide
What Is Niclosamide?
Niclosamide is an FDA-approved anthelmintic used since the 1960s to treat tapeworm infections. It has an exceptional long-term safety record and is on the WHO List of Essential Medicines. Despite its decades of safe use, it has attracted enormous research interest for repurposing due to its remarkably broad anti-cancer and anti-inflammatory mechanisms.
How Niclosamide Works
Niclosamide is arguably the most mechanistically rich repurposed agent in integrative medicine:
- STAT3 inhibition — suppresses one of the most important oncogenic and pro-inflammatory signaling pathways; STAT3 drives tumor cell survival, proliferation, immune evasion, and inflammatory cytokine production across virtually all cancer types and many autoimmune conditions
- Wnt/β-catenin inhibition — reduces cancer stem cell self-renewal; relevant in colorectal, breast, and prostate cancer
- mTOR inhibition — reduces anabolic tumor metabolism, promotes autophagy (cellular cleanup), and reduces inflammatory signaling
- AMPK activation — restores the cellular energy sensor that normally restrains inflammatory and proliferative signaling
- NF-κB suppression — reduces tumor microenvironment inflammation
- Mitochondrial uncoupling — selectively impairs cancer cell energy production while increasing metabolic rate in normal cells
- Notch pathway inhibition — reduces cancer stem cell activity
- Reversal of epithelial-mesenchymal transition (EMT) — reduces metastatic potential
Safety Profile
Niclosamide has minimal systemic absorption at standard anthelmintic doses, contributing to its excellent safety record. At higher doses being investigated for repurposing, bioavailability enhancement formulations (nanoparticles, cyclodextrin complexes) are being developed to increase systemic levels. Medical supervision is essential for repurposing applications.
How to Access
Niclosamide is not currently widely available in the US as a standard prescription. Compounding pharmacies can prepare it. Access typically requires a functional medicine or integrative physician familiar with its repurposing applications.
DMSO (Dimethyl Sulfoxide)
What Is DMSO?
DMSO is an organosulfur compound originally derived as a byproduct of wood pulp processing. It has been used in medicine since the 1960s and is FDA-approved as a prescription medication (Rimso-50) for interstitial cystitis (bladder inflammation). It is also widely used in medical research as a cryoprotectant for cell preservation and as a carrier solvent for drug delivery.
How DMSO Works
DMSO’s therapeutic properties stem from several unique characteristics:
- Membrane penetration — DMSO penetrates biological membranes with extraordinary efficiency, carrying dissolved compounds with it; this makes it a powerful drug delivery vehicle, dramatically enhancing the penetration of co-administered agents into tissues
- Free radical scavenging — DMSO is a potent hydroxyl radical scavenger, reducing oxidative stress in inflamed and damaged tissues
- Anti-inflammatory — inhibits prostaglandin synthesis, histamine release, and inflammatory cytokine production
- Analgesic — reduces pain via multiple mechanisms including nerve conduction modulation
- Vasodilatory and anti-platelet — improves microcirculation and reduces platelet aggregation
- Differentiation induction — can induce cancer cell differentiation, causing them to revert toward normal cellular behavior
- Collagen dissolution — reduces abnormal collagen deposition in fibrotic conditions
The Garlic Odor
DMSO is metabolized to dimethyl sulfide (DMS), which is excreted through the lungs and skin, producing a characteristic garlic-like or oyster-like odor. This is harmless but can be socially inconvenient. The odor is dose-dependent and typically appears within 30–60 minutes of application.
Safety Profile
DMSO has a well-established safety profile from decades of medical and research use. Topical application can cause local skin reactions (redness, burning, itching) that typically resolve with dilution. Its membrane-penetrating properties mean that anything on the skin when DMSO is applied will also be carried into the body — skin must be clean before application. High-purity pharmaceutical-grade DMSO should always be used; industrial-grade DMSO may contain impurities that would be carried into tissues.
How to Access
Pharmaceutical-grade DMSO is available over-the-counter in many US states as a topical product (typically 70–99% concentration). Prescription Rimso-50 (50% DMSO) is FDA-approved for bladder instillation. For systemic or IV applications, medical supervision is required.
The Synergy Principle
One of the most important concepts in repurposed drug protocols is synergy — the combination of agents with complementary mechanisms produces effects greater than any single agent alone. Common synergistic combinations used in integrative protocols include:
- LDN + CBD — complementary immune modulation and neuroinflammation reduction
- Fenbendazole/Mebendazole + Ivermectin — complementary anti-cancer mechanisms (tubulin inhibition + PAK1/WNT inhibition)
- Niclosamide + Ivermectin — STAT3 + NF-κB dual suppression
- DMSO + any topical or systemic agent — enhanced tissue penetration and delivery
- Any repurposed agent + ketogenic diet — metabolic restriction synergizing with targeted molecular inhibition
For condition-specific protocol guidance, see our Specific Diseases & Ailments hub and our Supplement Stacking Guide.
Important Considerations
- Medical supervision is essential — repurposed drugs are real pharmaceutical agents with real drug interactions, contraindications, and dose-dependent effects; never self-prescribe
- Quality matters — pharmaceutical-grade products from reputable sources are essential; veterinary products (fenbendazole) vary in purity and formulation
- These are not cures — repurposed drugs are tools within a broader integrative protocol; they work best alongside dietary, lifestyle, and other therapeutic interventions
- The evidence base varies — LDN has robust clinical trial data; fenbendazole has primarily case reports and preclinical data; always understand the evidence level for any intervention you consider
This article is for educational purposes only and does not constitute medical advice. See our Educational Standards & Medical Disclaimer for full details.
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