How Do Pain Relievers Work?

Different types, different ways:

Shooting the messenger

Pain is not a fault in our body; it evolved for a reason and is there to serve a purpose, namely, letting us know about potential or actual damage to our body. For this reason, people who can’t feel pain are at much greater risk of injury because they may not notice damage to their bodies.

Where pain “comes from”: specialized nerve cells called nociceptors extend from your spinal cord to your skin, muscles, joints, teeth, and some internal organs, transmitting electrical signals to your brain only when something could cause or is causing damage.

In a move as useful as it is unpleasant, injuries increase pain sensitivity, because damaged cells release chemicals* that lower nociceptors’ pain threshold, making even gentle touch painful around an injured area.

^{*For those who would like more details than just nebulous “chemicals”, we will add the extra information that damaged cells release arachidonic acid, which the enzymes COX-1 and COX-2 convert into prostaglandin H2, the precursor to prostaglandins and related signaling molecules. And pain, as established, is just a matter of signals.}

As for some common ones:

• How aspirin works: aspirin permanently (for the life of each given enzyme, anyway, not for your lifetime, unless you die very quickly, of course) disables COX-1 and COX-2 by leaving part of its molecule lodged in each enzyme’s active site, preventing arachidonic acid from entering.
• How ibuprofen works: ibuprofen temporarily occupies the active site of COX-1 and COX-2, blocking arachidonic acid only while the drug remains bound before the enzyme can function again.
• Why these both affect the whole body: aspirin and ibuprofen circulate throughout your bloodstream rather than targeting only painful areas, so they act wherever COX enzymes are present.

You might be wondering why equally common painkiller paracetamol/acetaminophen (as in Tylenol et al.) didn’t get an explanation here, and the answer is that science doesn’t know how it works 🙂 There are some hypotheses and there have been some breakthroughs lately (see our “learn more” section for more on that), but simply put, we (humanity) just don’t know yet.

For more on all of this, enjoy:

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Want to learn more?

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Take care!