The Side Effects of Corn Silk

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Corn silk is made up of the soft, yellowish, thread-like fibers that cover a husk of corn inside the leaves. Known for its diuretic properties, some people use corn silk as an herbal remedy to treat urinary tract or prostate infections. Generally safe when taken as directed by a qualified herbalist, discuss the possible medical consequences with your doctor before taking this or any herbal supplement or remedy.

Natural Diuretic

Diuretics help the body get rid of excess fluids by causing you to excrete more urine. Although some herbs – including corn silk – have a natural diuretic effect, you should never try to treat water retention without talking to your doctor first. There may be a medical cause for the problem. Natural diuretics are an alternative to prescription medications. However, their effectiveness and potential side effects can differ. Not all herbal products are safer than pharmaceutical drugs.


Although corn silk is usually safe and does not produce negative side effects in most people, you may develop a skin rash if you are allergic to corn. Corn silk can also decrease the level of potassium in your blood. You should not take corn silk if you already have low potassium levels, low or high blood pressure, or diabetes. Children, pregnant women and women who are breastfeeding should not take corn silk. Since the government does not regulate dietary supplements, a corn silk product might contain other ingredients that may be harmful to your health. Corn silk may interact with other medications you are taking.

Prescription Medications

Because corn silk acts as a natural diuretic, taking corn silk in combination with water pills can decrease the levels of potassium in your blood. Corn silk taken along with corticosteroid medications to treat inflammation can deplete potassium as well. Taking large doses of corn silk decrease blood pressure; therefore, if you are already taking medications prescribed by your physician to treat high blood pressure, your blood pressure might drop too low. Another side effect of corn silk is that it can lower blood sugar. Your doctor may need to adjust the dosage of your diabetes medication if you take corn silk as a supplement. Corn silk contains high amounts of vitamin K – a nutrient the body uses to clot blood. This can reduce the effectiveness of prescription medications used to thin the blood.

Medicinal Uses

How much corn silk you should take depends on your age and overall health. Carefully follow the instructions on product labels. Use this and other herbal remedies and dietary supplements only under the supervision of your doctor or other licensed health care professional. Herbal supplements can be potentially dangerous, especially if you use them in combination with prescription medications you are taking. There have been few human studies examining the safety and effectiveness of most herbal remedies, according to doctors at Cleveland Clinic. However, the findings of one study published in the November 2009 issue of the journal "Nutrition and Metabolism" report that corn silk extract may increase insulin production, lowering blood sugar levels in diabetics.