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Cranberry Extract Side Effects

author image Carole Anne Tomlinson
Carole Anne Tomlinson is a registered nurse with experience in rehabilitation, nutrition, chemical dependency, diabetes and health problems related to the elderly. Tomlinson holds a Bachelor of Arts in criminal justice and is presently working on her master's degree in nursing. Her screenplays have been viewed by Merchant Ivory, Angela Lansbury and Steven King's associates.
Cranberry Extract Side Effects
Un-picked cranberries on the plant. Photo Credit sabinalbei/iStock/Getty Images

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.

Thinning of Blood

If you take a medication such as warfarin to help thin your blood to prevent clotting, you will need your doctor’s approval to use cranberry extract supplements. Taking this supplement can raise the level of efficacy of blood-thinning medicines, which can cause dangerous health problems. If your blood cannot clot properly, for example, even a minor cut could continue to bleed without cessation, which will need medical intervention.


Cranberry extract supplements, like many supplements, can produce a mild sensation of discomfort in your stomach, primarily as nausea. A new supplement requires an adjustment by your body to accommodate it. While this takes place, your digestive system may feel disturbed. Nausea from cranberry extract typically will cease on its own without help from a medical practitioner.


Another reason to consult your physician before using cranberry extract is that the supplement can make you susceptible to an infection in your bladder, Drugs.com notes. You may feel severe stomach pain or you may urinate less than normal or not at all because of the infection. You also may hurt when you urinate or feel a burning sensation. Blood may appear in your urine, a problem called hematuria. Seek medical aid for any signs you have an infection in your bladder and stop taking the extract.

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