A yellowish resin extracted from the guggul plant contains substances called guggulsterones and possibly others. Laboratory studies have found that guggulsterones can change the metabolism of cholesterol by the liver. Guggulsterones may also increase the production of thyroid hormones and are commonly included in weight loss supplements for that purpose. Products containing guggul extracts should be taken with caution because of their risk of side effects.
For thousands of years, guggul resin has been used in traditional medicine to treat rheumatism, arthritis, neurological diseases, hemorrhoids, urinary disorders and skin diseases. Modern medicine has found evidence that guggulsterones can act in the liver, correcting disorders of lipid metabolism such as high cholesterol. Through an unknown mechanism, guggulsterones also increase the thyroid gland's production of hormones, increasing energy utilization in the body.
Interactions with Medicines
Guggul extract should not be taken with warfarin, aspirin, nonsteroidal anti-inflammatory drugs or any other drugs that inhibit blood clotting. Guggul extract may increase the risk of severe or uncontrolled bleeding when taken with these drugs. Guggul extract may interact with synthetic thyroid hormones or other medications used to treat thyroid disorders. Taken together, guggul and thyroid medications can raise the risk of thyroid storm, a potentially life-threatening condition in which very large amounts of thyroid hormones are produced. Guggul extract may greatly reduce the effectiveness of the drugs propranolol or diltiazem.
Interaction with Disease
Those being treated for thyroid disorders, including both hypo- and hyperthyroidism, should consult their doctor before taking guggul extract. People with liver or kidney disease may not metabolize guggul extract normally and should not take it. In general, consult your doctor to determine whether guggul extract is safe for you.
Other Possible Side Effects
Little scientific information exists on the potential toxicity of guggul extract. It is unknown whether guggul is safe during pregnancy, but because of effects on thyroid hormones and lipid metabolism it should probably be avoided. Guggul extract may cause headache, nausea, gastrointestinal disturbances and rash. Allergic reactions to guggul extract have been reported.