Long COVID Treatment: Peptides, LDN, NAD+ and Testing
Forbes Health Advisory Board · Naturopathic Doctor · Updated October 19, 2026
Do peptides help long COVID? They can be one part of long COVID treatment, but the research is early and no peptide is FDA-approved for long COVID. At Med Matrix, a functional medicine clinic in South Portland, Maine, long COVID care can include IV peptides, low-dose naltrexone (LDN, prescribed off-label) and NAD+. Whether a patient gets any of them depends on what their labs and health history show, so the plan starts with testing.
That's the honest answer, and it's less exciting than most of what you'll find when you search this.
Long COVID patients tend to arrive tired of two things. Being told their bloodwork is normal. And reading confident lists of "the best peptides for long COVID" that never say how thin the evidence is. This article covers what each option is, what's actually known about it, and how a plan gets built around one person instead of a protocol.
What Long COVID Looks Like
Long COVID, also called post-acute sequelae of SARS-CoV-2 infection (PASC), is the name for symptoms that hang on for weeks or months after a COVID infection, or show up after it. It isn't one disease with one cause. Two people with the diagnosis can have very different problems underneath.
The symptoms people describe to us most often:
- Fatigue that rest doesn't fix, and sometimes gets worse after exertion
- Brain fog. Losing words, losing the thread of a conversation.
- A racing heart or dizziness when standing up
- Getting winded with very little activity
- Sleep that doesn't refresh, even when exhausted
- New gut trouble or food reactions that started after the infection
- Anxiety or low mood that wasn't there before
Then the standard workup comes back clean, and the advice is to rest and wait. "Everything comes back normal, but I don't feel normal" is close to word for word what we hear. A normal basic panel rules some things out. It doesn't explain the fatigue.
Do Peptides Help Long COVID?
Peptides are short chains of amino acids that act as signals in the body. Some are studied for how they affect immune activity and tissue repair, which is why they come up so often in long COVID forums. Research in long COVID itself is still early: small studies, case reports and lab work, not large trials.
We do use peptide therapy, including IV peptides, as part of long COVID care for some patients. It's a prescription decision, made after testing, with follow-up to see whether it's helping.
You won't find a fixed peptide list on this page. That's deliberate. The right choice for someone whose labs point to an immune problem is different from the right choice for someone whose fatigue turns out to be a thyroid issue, and for some patients the answer is no peptide at all. A list written for everyone fits nobody well.
Questions worth asking before you start any peptide
- What did my labs show that points to this?
- How will we know if it's working, and when do we check?
- Who is prescribing it, and where is it coming from?
- What else could explain my symptoms that we haven't ruled out?
Low-Dose Naltrexone (LDN) for Long COVID
Naltrexone is an older medication. At its standard dose it's FDA-approved for alcohol and opioid dependence. Low-dose naltrexone uses a much smaller dose, and using it for long COVID is off-label: the drug is approved, just not for this purpose.
Off-label prescribing is legal and common in medicine. It still means you should go in with clear eyes. LDN is not an approved long COVID treatment, the published evidence for this use is limited, and it's a decision your provider makes with you after reviewing your history and current medications.
We prescribe LDN off-label for some long COVID patients. It's never the whole plan.
NAD+ and Long COVID
NAD+ is a coenzyme your cells use to turn food into energy. Because fatigue is the symptom long COVID patients struggle with most, NAD+ gets a lot of attention.
Be careful with the claims around it. A September 2026 review in Frontiers in Aging called the evidence for IV NAD+ preliminary, built mostly on small uncontrolled studies and case reports. Anyone promising that an NAD+ drip will fix post-COVID fatigue is ahead of the research. We include NAD+ in some long COVID plans, through our IV therapy service, alongside the rest of the work, and we watch how each patient responds.
Why Testing Comes First
Long COVID symptoms overlap with a lot of other problems. Thyroid dysfunction causes fatigue, brain fog and cold intolerance. Shifts in sex hormones and cortisol affect sleep, mood and energy. Low vitamin D or other nutrient gaps show up as exhaustion. An infection can also make an existing problem worse, so the symptom may be new while the cause is not.
Treating long COVID without checking for these is guessing. So every new patient starts with an 80+ biomarker panel and a full body composition scan. It includes markers like a full thyroid panel (not TSH alone), inflammation markers such as hs-CRP, vitamin D, and hormone levels. Labs can be drawn in our office or at a partner lab near you.
Sometimes the testing finds something treatable that has nothing to do with peptides. That's a good outcome.
How a Long COVID Plan Comes Together
Long COVID patients go through the same five steps as everyone else at our clinic:
- Free Discovery Call. Talk with our patient coordinator about your goals, symptoms and concerns.
- 80+ Biomarker Test & Full Body Scan. Lab panel, body composition scan and in-depth health questionnaires.
- Medical Team Reviews Everything. Providers review your labs, medical history and questionnaires before you meet.
- 60-Minute Provider Consultation. A full hour going over every result and building your plan together.
- Ongoing Support & Progress. Continued monitoring of your labs and markers, and adjustments as your body responds.
That last step matters more with long COVID than with most conditions. Recovery rarely runs in a straight line, and a plan that made sense in month one may need to change by month three.
What Else the Research Is Looking At
Long COVID research is moving, and some of the most interesting results have nothing to do with peptides.
One example. A small pilot trial published in Frontiers in Nutrition in March 2026 tested creatine in adults with fatigue lasting more than 12 weeks after COVID. A modest daily dose, given alongside physical rehab, eased fatigue more than placebo. A dose three times higher did nothing. It's one small study, and creatine is not part of our long COVID protocol. It's a useful reminder that more isn't automatically better, and that the field is still sorting out what works.
If exercise leaves you flattened for a day or two afterward, tell your provider before anyone hands you a workout plan. That pattern, called post-exertional malaise, changes how activity should be approached.
Long COVID Care in South Portland, Maine
We see long COVID patients at our one office, 198 Maine Mall Road in South Portland, and patients come from across Maine and New Hampshire. Our long COVID treatment page covers the condition in more depth, and our functional medicine page explains the broader approach. If fatigue is the main problem, the fatigue page and the sleep page are good next reads.
If you've been told to rest and wait and you're done waiting, Book Your First Visit.
Frequently Asked Questions
Do peptides help with long COVID?
Peptides can be one part of long COVID treatment, but the research is early and no peptide is FDA-approved for long COVID. At Med Matrix, IV peptides are used for some long COVID patients after lab testing, alongside low-dose naltrexone and NAD+ where they fit. Which peptide, if any, depends on what a patient's labs and history show.
Which peptides are used for long COVID?
There is no standard peptide list for long COVID, and Med Matrix does not publish one. The choice depends on what testing shows, and for some patients the right answer is no peptide. A provider should be able to explain what in your labs points to a specific peptide and how you'll both know whether it's working.
Is low-dose naltrexone approved for long COVID?
No. Naltrexone is FDA-approved at its standard dose for alcohol and opioid dependence. Using low-dose naltrexone for long COVID is off-label, which is legal and common, but the evidence for this use is limited. Med Matrix prescribes LDN off-label for some long COVID patients as one part of a broader plan.
Does IV NAD+ help long COVID fatigue?
The evidence is preliminary. NAD+ is a coenzyme cells use to make energy, which is why it is studied for fatigue, but a 2026 review of intravenous NAD+ found the evidence too thin to support routine use. Med Matrix includes NAD+ in some long COVID plans and monitors each patient's response.
What tests help with long COVID?
Testing looks for treatable problems that cause the same symptoms as long COVID. Med Matrix starts with an 80+ biomarker panel and a body composition scan, including thyroid markers, inflammation markers such as hs-CRP, vitamin D and hormone levels. Labs can be drawn in the office or at a partner lab.
Where can I get long COVID treatment in Maine?
Med Matrix treats long COVID at its office at 198 Maine Mall Road in South Portland, Maine, and sees patients from across Maine and New Hampshire. Care starts with a free discovery call, then testing and a 60-minute provider consultation.