When many of us get a headache, a fever, or just suffer the aches and pains of physical exertion we don’t think twice about reaching for an over-the-counter pain reliever.  Acetaminophen, which is the medicine in the well-known brand Tylenol, has long been considered the safest pain medication.  Non-steroidal anti-inflammatory medications (NSAIDs) can cause stomach irritation and ulcers and can decrease kidney function.  Opiates (morphine and its relatives) can cause drowsiness, constipation and...