For example, in the case that you step on a nail, you feel pain and step back quickly to prevent the nail from puncturing your foot more deeply.
Therefore, this type of pain is on our side.
When you injure somewhere in your body, our body transmits a signal of pain and causes inflammation including redness, heat, swelling and pain. This is considered as acute pain. If this pain signal continues for a long time, our nerve memorizes the pain and the pain becomes chronic even after the injury is cured. So it is important to control the pain at the beginning of the injury not to make the pain chronic.
That is why it is okay to use painkiller (anti-inflammatory analgesics) or icing in the case of acute joint pain with severe pain.
Why Painkiller should not be used for chronic pain?
Because painkiller is not effective against chronic pain.
Painkiller prevents the production of the substance to dilate the blood vessel and contracts the blood vessel, preventing the blood flow. Our body wants to provide a lot of blood to the diseased area to supply nutrition that improves the injury. But continuous use of painkiller prevents the improvement of blood flow and delays the cure.
Therefore, painkiller is proper to be used for acute pain for a short period of time and should not be used for chronic pain.
The same is true of cold patch (topical anti-inflammatory analgesics).