Herbalists may recommend the use of supplements of cranberry extract if you suffer from a urinary tract infection, the National Center for Complementary and Alternative Medicine reports. The organization recommends only using such a supplement if your physician approves it. You also may find other uses for it such as those presented by Drugs.com that include reducing bladder pain and helping to control incontinence. While cranberry extract supplements appear to have some medicinal value, the U.S. Food and Drug Administration does not approve it for use as a drug. Ask your doctor before taking any form of supplement.

Kidney Stones When you use cranberry extract as a supplement, especially if you are prone to kidney stones, the raised level of oxalates in your body increases the kidney stone risk. The University of Maryland Medical Center notes that more of these chemicals in your body may produce the kidney stones, which are small, hardened bits of material. If kidney stones occur, you may find that as they travel from your kidneys to your bladder and then through the urethra that you experience severe pain. This traverse also may cause blood to appear in your urine and can damage the organs affected. If you already have had kidney stones, speak with your physician about the use of this supplement first.