Side effects of cranberry pills

Cranberry pills are a natural supplement composed of cranberry extract, which may be taken as an alternative treatment for urinary tract infections. Although cranberry pills are relatively safe, there are a few possible side effects and drug interactions to be aware of when taking cranberry pills.

Mild Side Effects

Side effects of cranberry pills may include diarrhoea, dizziness, fatigue, frequent urination, headache, nausea and stomach cramping. Facial redness or blurred vision may also occur.

Serious Side Effects

Cranberry supplements have been associated with kidney stones, due to a high level of oxalate which can increase the risk of kidney stones. Serious side effects of cranberry pills are rare.


If taking antacids, cranberry pills may decrease their effectiveness. Cranberry supplements are known to interfere with the blood clotting effects of the drug Warfarin.


People who are allergic to cranberries, blueberries or benzoic acid may experience an allergic reaction to cranberry pills. An allergic reaction to cranberry supplements may include hives, itching or difficulty breathing.


Because cranberries are high in sugar, diabetics should carefully monitor their blood sugar level when taking cranberry pills.