Low Dose Naltrexone (LDN)

Naltrexone is an opioid antagonist that is commercially manufactured at higher strengths. Low Dose Naltrexone, often shortened to LDN, refers to smaller prescribed strengths that are used off-label in some care plans.

Common compounded strengths include 0.5 mg, 1 mg, 1.5 mg, 2 mg, 3 mg, and 4.5 mg capsules. Very Low Dose Naltrexone (VLDN) generally refers to doses below 1 mg, while Ultra Low Dose Naltrexone (ULDN) refers to microgram dosing. Those categories should be written clearly on the prescription because the scale is different.

LDN is prescribed off-label for a variety of conditions, including:

• Fibromyalgia
• Multiple sclerosis (MS)
• Crohn's disease and inflammatory bowel conditions
• Complex regional pain syndrome
• Chronic fatigue syndrome
• Certain autoimmune conditions

Research into LDN's applications is ongoing. For current research information, visit the LDN Research Trust.

At low doses, naltrexone is thought to work by briefly blocking opioid receptors, which triggers the body to increase production of endorphins and enkephalins — the body's natural pain-relieving and immune-regulating compounds.

This temporary blockade is believed to result in an "upregulation" of the immune system, which may help modulate the immune response in autoimmune and inflammatory conditions.

LDN is generally well tolerated. Possible side effects, particularly when starting treatment, may include:

• Vivid dreams or sleep disturbances (usually temporary)
• Mild headache
• Nausea
• Anxiety or mood changes (uncommon)

Most side effects diminish within the first few weeks of treatment. Taking LDN at bedtime may help manage sleep-related side effects.

LDN is typically taken once daily, usually at bedtime. Your physician will determine the appropriate starting dose, which is often gradually increased over several weeks.

Important: LDN should not be taken concurrently with opioid medications, as it may precipitate withdrawal. Inform your doctor of all medications you are taking.

Many LDN prescriptions start at a lower strength and increase gradually. A prescriber may write a schedule such as 0.5 mg or 1 mg nightly to start, then increase over several weeks toward a target such as 3 mg or 4.5 mg.

The label should make each step clear. Ask the pharmacy or prescriber before changing the dose, combining strengths, or continuing an old strength after a new step begins.