A million-dollar wound or Blighty wound is military slang referring to a type of wound received in combat which is serious enough to get the person sent away from the fighting, but is not fatal, nor will it leave the person permanently crippled.
In conclusion, Benadryl does not cause kidney damage directly, but if you uses excessively over a long period of time and there is urinary retention, the chronic urinary retention could ending producing kidney failure.
Benadryl Side Effects. Although most people do not experience problems while taking Benadryl, it's possible to have side effects. Based on the limited information from prescription Benadryl products, common side effects may include drowsiness, heartburn, and dizziness.