Garcinia cambogia is an herb included in several supplements for weight loss and fat burning. Derived from the rind of the gamboge fruit, which is native to Asia, Garcinia cambogia extract also is used to lower high cholesterol. The active ingredient, which might have benefits for weight loss, is hydroxycitric acid (HCA). Garcinia cambogia extract is generally safe and side effects are rare.

High-Dose Side Effects

Excessive consumption of Garcinia cambogia extract can cause gastrointestinal side effects, according to EMedTV and Green Herbal Remedies. People taking large amounts of this herb might experience stomach or intestinal pain, nausea, vomiting and diarrhea. Headaches are another possible side effect.

Blood Sugar Effects

Hydroxycitric acid, the active ingredient in Garcinia cambogia extract, can lower blood sugar levels. People with diabetes might need to monitor their blood sugar more closely when taking this herb, as noted by eMedTV. Diabetic patients taking medications such as metformin or insulin to control blood sugar levels might need to have their health care provider adjust the dosage.