Cornsilk is a miracle worker. If you catch a bladder infection early enough and use enough it will fix it, but not if you let it get a hold.. For kidneys its usefulness cannot be overstated. I have kidney pain from time to time - I think never having drunk enough water could be the cause, but my right kidney is sensitive and gives me pain at times. Cornsilk tincture, anything from a teaspoonful to 2 tablespoons, will stop it in anything from 10 mins to an hour. If it isn't better in half an hour I just take more.
My father had only one kidney, after cancer/chemo that one had 30 percent function. He took cornsilk tablets daily and never had a problem unless he skipped them for a couple of days. I can't buy the tablets any more because cranberry got fashionable and the compny that used to make them here ditched them in favour of cranberry (useless for kidneys) but I can get cornsilk tincture from a variety of homoeopathic/compounding chemists and on line. Never be without it! (I've never heard of contra-indications with it though my mother in law was a bit concerned about my using it during pregnancy)