Long COVID: Autoimmune Connections, Symptoms, and Comprehensive Treatments with LDN and Functional Medicine in San Antonio, TX & Quincy, IL

By Yoon Hang Kim Integrative & Functional Medicine Physician — Serving Patients in San Antonio, TX, Quincy, IL, and IL, MO, GA, TX, FL via Telemedicine

Understanding Long COVID

Long COVID, also called Post-Acute Sequelae of SARS-CoV-2 Infection (PASC), impacts up to 43% of people after COVID-19, with symptoms lasting months or years. Many patients in San Antonio and Quincy come to me after struggling to find answers in conventional medicine.

Emerging research suggests autoimmune-like mechanisms play a major role, which is why immune-modulating therapies—like low-dose naltrexone (LDN) and functional medicine—are gaining attention.

The Autoimmune Connection

Long COVID shares similarities with chronic autoimmune and inflammatory conditions such as:

• ME/CFS (chronic fatigue syndrome)

• Fibromyalgia

• Crohn’s disease

Possible mechanisms include:

• Persistent inflammation – High cytokine levels (IL-1β, IL-6, TNF) driving fatigue and brain fog.

• Immune dysregulation – Dysfunctional NK cells and altered TRPM3 ion channels.

• Autoimmune overlap – Chronic pain and cognitive impairment resembling autoimmune diseases.

Common Symptoms I See in San Antonio & Quincy Patients

Whether you’re in Texas or Illinois, the symptom profile is strikingly similar:

• Severe fatigue (often worse after activity)

• Brain fog and poor concentration

• Muscle and joint pain

• Unrefreshing sleep or insomnia

• Dizziness, palpitations, orthostatic intolerance

• Ongoing shortness of breath

• Neurological symptoms like headaches, tingling, mood changes

📊 In a 2023 study of 968 patients, 85% still had symptoms one year after onset.

Low-Dose Naltrexone (LDN) for Long COVID

In my virtual functional medicine practice serving San Antonio and Quincy, LDN is one of the most-requested therapies for Long COVID.

Why LDN Helps

• Calms neuroinflammation by blocking TLR-4 receptors on microglia

• Balances immune system overactivity via T-regulatory cell enhancement

• Boosts natural endorphins for pain relief and mood support

Evidence

• 2023 study – Improved fatigue, brain fog, and sleep in 59 patients

• 2024 pilot – LDN + NAD+ supplementation improved quality of life

• 2025 research – Restored NK cell TRPM3 channel function

Functional Medicine: A Root-Cause Approach

Functional medicine goes beyond symptom control to address underlying drivers of Long COVID.

In both my San Antonio TX and Quincy IL telemedicine practice, we focus on:

1. Gut Health Restoration

• Probiotics & prebiotics

• Anti-inflammatory diet (omega-3 rich, gluten- and dairy-free)

• Gut repair nutrients like L-glutamine

2. Nutrient Repletion

• Vitamin D (2,000–5,000 IU/day)

• Magnesium (200–400 mg/day)

• Coenzyme Q10 for mitochondrial function

3. Mitochondrial Support

• Acetyl-L-carnitine, alpha-lipoic acid

• Methylene blue

• Energy pacing strategies

4. Stress & Nervous System Regulation

• Mind-body practices (meditation, breathwork)

• Adaptogenic herbs

5. Toxin Reduction

• Mold and heavy metal assessment

• Liver support (NAC, milk thistle)

Combining LDN and Functional Medicine

The most effective plans I’ve seen often combine:

• LDN 4.5 mg nightly

• Anti-inflammatory diet + targeted probiotics

• Vitamin D and mitochondrial support

• Pacing and stress management techniques

This integrated approach addresses both immune dysregulation and whole-body health.

Additional Supportive Therapies

• Physical therapy for strength and endurance

• Symptom-specific medications (antihistamines, antidepressants)

• Stellate ganglion block for dysautonomia

📍 Dr. Yoon Hang Kim, MD offers integrative and functional medicine services in Quincy, IL, and via telehealth in Georgia, Florida, Illinois, Missouri, and Texas.

🔗 Learn more or schedule a consultation: www.directintegrativecare.com