Common Side Effects of Cranberry Products
Cranberry supplements, juice, or extracts cause mild stomach upset, diarrhea, or nausea in some users, especially at high doses over 1,000 mg daily or with large juice volumes. These resolve after stopping use.[1][2]
Risks for Kidney Stone Patients
Cranberry raises oxalate levels in urine, increasing calcium oxalate kidney stone risk for susceptible people. Avoid if you have a history of these stones.[1][3]
Who Should Avoid Cranberry?
Pregnant or breastfeeding women lack strong safety data, so caution is advised. Those on warfarin face higher bleeding risk due to cranberry's effect on blood clotting. Aspirin-sensitive individuals may get worsened allergy symptoms.[2][4]
Drug Interactions to Watch
Cranberry can amplify effects of blood thinners like warfarin, raising INR levels and bleeding odds. It may also interact with diabetes drugs by lowering blood sugar or with lithium by slowing its clearance.[1][4]
Overdose or High-Dose Effects
Excessive intake (e.g., multiple liters of juice daily) leads to stomach cramps, vomiting, or rapid heartbeat. No specific antidote exists; supportive care manages symptoms.[2]
[1]: NIH Office of Dietary Supplements - Cranberry
[2]: WebMD - Cranberry Side Effects
[3]: Mayo Clinic - Cranberry
[4]: Drugs.com - Cranberry Interactions