Low Dose Naltrexone and chronic pain

Opioids have been used as universal pain killers for centuries. However, everyone knows about the effect of drug addiction and other unpleasant aftermaths of their use. That is why the ability of naltrexone to suppress the chronic pain of a certain etiology is very important. The list of syndromes when naltrexone is effective includes CRPS (complex regional pain syndrome), reflex sympathetic dystrophy, diabetic peripheral neuropathy, and some immune-based kinds of pain. A 30 to 60% reduction of pain symptoms was registered in the research in treating FB (fibromyalgia) with LDN (low dose naltrexone). So, what is the mechanism behind the influence of naltrexone on the nerve pain?

The central nervous system (CNS) is composed of nerves and so called glial cells (or just glia). The latter account for about eighty percent of CNS, and only the rest twenty percent are nerves. The glia cells are responsible for the immune protective forces of the body. Normally, under healthy conditions, glial cells are passive. They get active only in response to infection or injury. So, what always happens when the brain and/or spinal cord (e.g. CNS) are inflamed is activation of glial cells.

Active glia cells trigger the secretion of a number of substances, such as interferon and interleukin, which are generally known as pro-inflammatory and neurotoxic factors. Some fatty acid metabolites and free radicals also play the role of factors. Some of these factors, when generated in the spinal cord, alleviate the painful state of inflammation.

What is important, opioids also shift the glia cells into an active state. There are medicines capable to block the effect of opioids, and naltrexone is one of them. Using naltrexone in low dose (LDN) can therefore inhibit the activation of glia.

Cells communicate with each other using special chemicals called neurotransmitters. The most common neurotransmitter in CNS is glutamate. It activates a special receptor called NMDA (N-methyl D-aspartate) and thus opens up the way for the entry of calcium into the cell. The nerve fires this way.

Summarizing, the activated glia cells release special chemicals and neurotransmitters which, through NMDA receptors, cause the nerves to fire. LDN inhibits the activation of glial cells, decreases the release of glutamate neurotransmitter and thus blocks the activation of NDMA receptors and the firing of nerves.

How Naltrexone Operates

The problem is that most medical practitioners are not familiar with naltrexone. Most likely, you will have to get your physician acquainted with this medication. This article can be useful to this end.

Naltrexone in low dose needs time to take effect. According to reports, an essential difference can be noticed after nine to twelve months. In that period, such symptoms as pain, poor functioning, and tolerance to pain gradually improve. The progression of disease slows down. LDN promotes the production of endorphins (morphine-like substances) which also results in a better mood and lower depression. Such factors essentially increase the healing effect.

Safety Measures

Naltrexone is a well-tested drug; in particular, there have been a number of studies on LDN administered at the level of 50 to 100 mg. It has proven to be quite safe at such dosage; at larger dose like 100 to 300 mg it may affect the liver. Patients with liver or kidney problems should be monitored by their physicians while using naltrexone.

Naltrexone is quickly excreted from the body; this means that when opioid use is required for reducing pain, there must be no withdrawal syndrome symptoms. Consult your doctor as to the period of time after which your body is clear from naltrexone, and using opiate-based medications is safe. The required time may vary depending on dosage and body weight.


Naltrexone can be taken along with other drugs provided that they contain no opiates. LDN blocks the opioid receptors, which means that such pain killers as fentanyl, demerol, pethidine, tramadol, morphine, oxycodone and hydrocodone will have no effect and, furthermore, can lead to withdrawal problems. Taking naltrexone must be stopped in good time if your doctor plans to prescribe you opiate-based medications.

Possible Side Effects

Side effects (sleep disturbance, insomnia, vivid dreams) are not likely to occur on one condition: taking LDN should be started from the lowest possible dose and increased very slowly. If side-effects nevertheless take place, the dose should be reduced. LDN is recommended to take in the morning to avoid sleep disturbances.

Recommended Dose

The recommended dose is between 1.5 and 4.5 mg taken either before going to bed or in the morning in case of insomnia.

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