Low Dose Naltrexone (LDN): Uses, Side Effects, and Evidence

Low dose naltrexone (LDN) is naltrexone, a prescription opioid-blocking medicine, used at a small fraction of its standard dose. Some clinicians prescribe it off-label for chronic pain and inflammation-related conditions such as fibromyalgia, but the research is mixed and still limited. LDN is not sold over the counter. You need a prescription, and it is usually made by a compounding pharmacy.

This guide covers what low dose naltrexone is, what the studies actually show, the most common LDN side effects, the opioid interaction everyone should understand, how LDN differs from the naltrexone and bupropion combination used for weight management, and how to get an LDN prescription online through a licensed clinician. It does not give dosing instructions. Your prescriber decides whether LDN fits and how you take it.

What is low dose naltrexone?

Low dose naltrexone is a much smaller dose of naltrexone, a drug FDA-approved at standard doses to treat alcohol dependence and to block the effects of opioids. At low doses it is used off-label, meaning for purposes the FDA has not approved. Because no commercial low-dose product exists in the U.S., pharmacies usually compound it.

A few points help set expectations:

• It is not an opioid. Naltrexone is an opioid antagonist, which means it blocks opioid receptors instead of activating them. It is not a painkiller in the usual sense.
• It is off-label. Off-label prescribing is legal and common, but it means the FDA has not reviewed evidence that LDN works for these uses.
• It is usually compounded. Compounded medicines are prepared by a pharmacy for an individual prescription. They are not FDA-approved and do not go through FDA review for safety, effectiveness, or quality before they reach you. If you want a plain-language explanation of what that means, our guide to what compounded medication means walks through the same questions for another drug class.

How is LDN thought to work?

Researchers believe a low dose briefly blocks opioid receptors, which may prompt the body to make more of its own endorphins once the block wears off. LDN may also calm certain immune cells involved in inflammation. These ideas are plausible but not proven, and they do not guarantee that LDN will help any particular person.

This is very different from how standard-dose naltrexone works. At full doses, the drug keeps opioid receptors blocked around the clock, which is useful for preventing relapse to opioid use. The low-dose theory depends on a short block followed by a rebound, which is part of why scientists still debate how, and whether, it works for pain and inflammation.

What does the research on LDN actually show?

The evidence is early and mixed. A small 2013 crossover study in women with fibromyalgia found less pain with LDN than with placebo, but a larger, well-designed 2024 trial found no meaningful pain benefit. For other conditions, most data come from small studies and case reports, and experts say larger trials are needed.

What this means for you: LDN is a reasonable thing to discuss with a clinician if you live with a hard-to-treat condition and understand that results vary. It is not a proven treatment, and it should not replace care that has stronger evidence. If you try it, a clear plan for what "better" looks like, tracked over several weeks, helps you and your clinician decide whether to continue.

What are the side effects of LDN?

The most commonly reported LDN side effects are sleep changes, especially vivid dreams or trouble sleeping, plus headache, nausea, dizziness, and fatigue. These are often mild and may fade over the first few weeks. Rare but serious problems include liver injury, major mood changes, and allergic reactions, which need prompt medical attention.

Common side effects

• Vivid dreams, restless sleep, or mild insomnia
• Headache
• Nausea or stomach upset
• Dizziness or tiredness
• Irritability or mood changes

Get medical help right away if you notice

• Yellow skin or eyes, dark urine, or severe pain in the upper right belly, which can signal liver trouble
• New or worsening depression, or any thoughts of self-harm
• Hives, facial swelling, or trouble breathing
• Fainting, severe weakness, or symptoms that get worse quickly

The FDA label for standard-dose naltrexone tablets warns about liver injury and reports depression and suicidal thoughts in some patients, without proving the drug caused them. Those warnings come from much higher doses, but your clinician will still screen for liver disease and mood history before prescribing LDN.

Why is the opioid interaction so important?

Naltrexone blocks opioids, so it can trigger sudden withdrawal in anyone who uses opioids regularly and can stop opioid pain medicine from working. The FDA label calls trying to overpower the block with large opioid doses especially dangerous, with a risk of fatal overdose. Never combine LDN with opioids unless your prescriber is fully informed.

Opioids show up in more places than people expect. Tell your clinician if you use or might need any of these:

• Prescription pain medicines such as oxycodone, hydrocodone, morphine, codeine, or tramadol
• Cough syrups that contain codeine or other opioids
• Some prescription diarrhea medicines
• Opioid use disorder treatment such as methadone or buprenorphine

Plan ahead for procedures, too. If you have surgery, a dental procedure, or an emergency, the care team needs to know you take naltrexone because it changes how they manage pain. The naltrexone label describes non-opioid approaches, such as regional anesthesia and non-opioid pain relievers, for people on full opioid blockade. Keeping an up-to-date medication list on your phone is a simple habit that helps here. Our drug interaction checklist was written for GLP-1 users, but its advice about sharing a complete list with every provider applies to LDN as well.

Is low dose naltrexone the same as naltrexone and bupropion for weight loss?

No. LDN is naltrexone alone at a low dose. The FDA-approved weight management drug Contrave combines extended-release naltrexone with bupropion, an antidepressant, and was approved in 2014 for adults with obesity, or overweight plus a weight-related condition. Searching for "low dose naltrexone weight loss" usually leads to confusion between the two.

Key differences to know:

• Purpose. Contrave is approved for chronic weight management alongside diet and exercise. LDN has no approved weight-loss use.
• Ingredients. Contrave pairs naltrexone with bupropion, which acts on appetite and reward pathways. LDN contains only naltrexone.
• Warnings. Contrave carries a boxed warning about suicidal thoughts and behaviors and can raise seizure risk because of the bupropion.

StemVera's oral weight loss capsules are a separate, compounded option. Depending on your plan and clinician review, the capsule may combine naltrexone and bupropion with metformin, topiramate, and methylcobalamin, a form of vitamin B12. It is not Contrave or any other FDA-approved product, and it carries its own screening for pregnancy, opioid use, seizures, mood, blood pressure, kidney health, and vision. You can compare it with GLP-1 and other options on the weight loss hub.

Is low dose naltrexone over the counter?

No. Naltrexone at any dose is a prescription-only medicine in the U.S., and low-dose versions are usually compounded for an individual patient. Any website selling LDN without a prescription and a clinician review is a red flag. Safe access means a licensed prescriber, a licensed pharmacy, and a full check of your medications.

Because LDN is compounded, pharmacy quality matters. A licensed pharmacy should label your medicine clearly with its strength, your name, and directions from your prescriber. If anything about the product looks different from what you expected, ask your pharmacist or care team before taking it.

Who should not take LDN?

LDN is generally not appropriate if you use any opioid, expect surgery or opioid pain treatment soon, or have significant liver disease. People who are pregnant, trying to conceive, or breastfeeding need individualized advice, and LDN through StemVera is for adults only. A history of depression or severe kidney disease calls for extra review.

Your clinician may advise against LDN, or ask for more information, if you:

• Take opioid pain medicine, opioid-containing cough or diarrhea medicine, or opioid use disorder treatment
• Have opioid withdrawal symptoms or recent opioid use
• Have liver disease or unexplained abnormal liver tests
• Are pregnant, trying to become pregnant, or breastfeeding
• Have severe kidney disease
• Have had a severe allergic reaction to naltrexone
• Are under 18

When to see a doctor in person

LDN is not a substitute for an in-person diagnosis. See a clinician face to face if you have unexplained weight loss, fevers, night sweats, new joint swelling, blood in your stool, new numbness or weakness, or pain that is suddenly much worse. These symptoms need a proper workup before anyone tries an off-label treatment.

How to get started with low dose naltrexone through StemVera

You can request an LDN prescription online in a few steps. Pick the treatment, complete a short health questionnaire, and a licensed clinician reviews it, with a video visit when required. If LDN is appropriate, a licensed pharmacy ships it discreetly, and your care team checks in on side effects and progress.

StemVera's LDN program uses a daily oral capsule. Your clinician chooses the strength, and plans are shown as four-week supplies with no subscription required. For costs, see current pricing on the low dose naltrexone page.

1. Choose your treatment. Review the low dose naltrexone page, or browse related options on the anti-aging and wellness hub.
2. Complete your health questionnaire. List your symptoms, goals, conditions, allergies, and every medication and supplement, especially anything that contains an opioid.
3. Clinician review. A U.S.-licensed clinician screens for opioid interactions, liver risk, and mood history, and decides whether LDN is safe for you. Some patients need a video visit, and some may be asked for lab work.
4. Pharmacy fulfillment. If prescribed, a licensed pharmacy prepares and ships your medicine with tracking.
5. Follow-up. Message your care team about side effects, questions, or any change in your health, and contact them right away if you might need opioid pain relief.

Our how it works page explains each step in more detail. If you are building a broader wellness plan, our guide to who actually needs B12 injections is another honest look at what the evidence does and does not support.

Bottom line

Low dose naltrexone is an off-label, usually compounded prescription with mild common side effects and one critical rule: it does not mix with opioids. Evidence for fibromyalgia and other conditions is mixed and still developing. If you want to try it, do it with a clinician who screens carefully and tracks results.