They act like a sponge and absorb the pain.

No.

When something is causing us damage, such as tip of a needle or pencil.

Special cells called nociceptors send signals to the brain.

The brain then perceives it as pain.

However, when cells of our body are severely damaged or injured, they release chemicals like arachidonic acid.

Now, just like a key fits in a lock, the arachidonic acid fits perfectly in enzymes called COX-1 and COX-2.

Forming prostaglandin and other compounds.

These compounds increase the sensitivity of nociceptors due to which it pains or hurts more.

Now, the most common painkillers are aspirin and ibuprofen.

These painkillers work by attaching themselves to COX-1 and COX-2.

Thus blocking them and not allowing arachidonic acid to bind to them.

As a result, prostaglandin is not produced and the sensitivity of nociceptors decreases.

Hence, the pain begins to subside.