…Ibuprofen, and other NSAID medications, work by blocking your body’s production of certain natural substances that cause inflammation. The effect can help decrease swelling, pain, or fever. It is this process that researchers with McGill University in Montreal, Quebec, say can cause pain to become worse.
Normally, your body responds to a painful injury with inflammation, which is your body’s natural reaction to injuries and infections. Researchers believe that repeatedly blocking this inflammation with drugs like ibuprofen could lead to pain that is harder to treat.
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In a word, they block the normal healing process which involves inflammation and pain. ABN