A colorized Positron Emission Tomography (PET) scan showing the distribution of opioid receptors in the human brain.

An overdose drug shows promise for long COVID patients

Low-dose naltrexone is often used to treat chronic pain and autoimmune disorders. Now, for many struggling with debilitating post-COVID symptoms, it's one of the few treatments that works.

A transverse Positron Emission Tomography (PET) scan showing the normal distribution of opioid receptors in the human brain, from highest (red) through yellow and green to lowest (blue). Opioid receptors are located on the outer surface of nerve cells (neurons). When pain is detected by the body, endorphins are released and attach to the receptors, preventing the neurons from firing, and providing pain relief. Opioid drugs mimic endorphins. Overdose medication Naltrexone works by binding to and blocking opioid receptors. 
Image by PHILIPPE PSAILA, SCIENCE PHOTO LIBRARY
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