100 Migraine Drugs, A to Z: Low-dose naltrexone

Naltrexone is similar to naloxone, a drug used to reverse the effect of narcotic (opioid) overdose. Naltrexone is not used to reverse the effect of an overdose, but to treat opioid and alcohol dependence. (LDN) and is given as a monthly injection or a daily pill. Naltrexone blocks the body’s own endogenous morphine (endorphin) receptors. In theory, this should make the pain worse. However, low-dose naltrexone (LDN) seems to have the opposite effect. It is possibly explained by the fact that a small amount of naltrexone blocks the endorphin receptors for a short time, during which the body begins to make more endorphins in an attempt to overcome this block. After the effect of naltrexone wears off, this extra amount of endorphins provides relief of pain and by blocking other receptors (such as Toll-like receptor 4) and reducing inflammation, potentially produces other beneficial effects, most of which are not scientifically proven.

Inflammatory bowel disease (Crohn’s disease and ulcerative colitis) do seem to respond to LDN.

A study of 27 patients with chronic central pain syndromes at the Stanford Pain Management Clinic published in The Journal of Pain concluded that “The significant findings of decreased average pain scores and depression and improved physical function after prescribing this well-tolerated, inexpensive medication provides justification for larger, controlled trials in patients with central sensitivity syndromes.” Some of these central sensitivity syndromes include migraine, fibromyalgia, irritable bowel syndrome, chronic back pain, and other.

Naltrexone is available only in a 50-mg tablet, while LDN is started at 1.5 mg nightly for a week, then 3 mg nightly for a week, and then, 4.5 mg nightly. This regimen requires a compounding pharmacy to make capsules containing 1.5 mg for the first two weeks and then, capsules with 4.5 mg. Some of my patients went up as high as 9 mg nightly. Compounded drugs tend to be more expensive than factory-made generics but because naltrexone itself is cheap, the cost of 30 capsules can be as low as $50.

Because the dose is low, side effects are rare. These include vivid dreams and insomnia and if these occur, the medicine can be taken in the morning.