Ginkgo Biloba

Ginkgo biloba is a leaf extract from the leaves of ginkgo biloba tree, used as a dietary supplement in a wide variety of conditions. Ginkgo biloba is typically taken orally as tablets, capsules, teas or liquid extracts and is widely available over-the-counter in the U.S. The exact formulation of ginkgo biloba may vary from manufacturer to manufacturer.

Ginkgo biloba leaves contain a complex mixture of compounds, two of which are the primary active components, terpene lactones and ginkgo flavone glycosides, which are present in varying concentrations. Animal (rodents) studies show evidence of following properties in ginkgo biloba:

• Reduces stress-induced hypersecretion of corticosteroids from the adrenal glands.
• Improves nerve signaling (neurotransmission) by inhibiting the activity of brain enzymes such as monoamine oxidase and anticholinesterase that break down neurotransmitters including dopamine, serotonin and norepinephrine.
• Acts as an antioxidant and scavenges free radicals, protecting nerve cells (neurons) from damage and death from oxidative stress. Oxidative stress is caused by an imbalance in the levels of free radicals and antioxidants that can neutralize them.
• Appears to improve short-term memory and age-related changes in the brain in middle and old age.
• Reduces inflammatory activity and blood clotting process by blocking platelet-activating factor, a substance that activates many inflammatory cells and signals the platelets to aggregate to form clots, in response to injury or inflammation.
• Dilates blood vessels and improves blood flow.

The suggested uses of ginkgo biloba include the following:

• Altitude sickness prevention
• Reduction of cardiovascular disease risk
• Cerebral vascular insufficiency
• Cognitive disorders
• Dementia
• Dizziness and vertigo
• Intermittent claudication, a peripheral artery disease symptom, that causes pain in the limbs due to reduced blood flow when moving the limbs (while exercising, for instance)
• Macular degeneration, an age-related condition that causes damage to macula, the central portion of the retina
• Glaucoma, a condition with high intraocular pressure that damages the optic nerve
• Memory loss
• Premenstrual syndrome (PMS)
• Sexual dysfunction induced by the use of selective serotonin reuptake inhibitors (SSRIs), drugs used to treat depression
• Vasodilation

Ginkgo biloba is marketed in the U.S. as a dietary supplement and does not have to undergo the rigorous testing for safety and efficacy that drugs do before they are approved for marketing. The FDA has not approved any of the suggested uses of ginkgo biloba and there is insufficient evidence to support these uses. Clinical studies in humans so far have not demonstrated definitive efficacy in any of ginkgo’s uses.

The National Toxicology Program (NTP) conducted a 105-week long study on the long-term effect of ginkgo biloba extract in mice and rats. The study was initiated by the National Cancer Institute (NCI) because of ginkgo’s widespread use and lack of information on its carcinogenicity and toxicity. The NTP study found an increase in liver cancer in male and female mice, and in cancer of the thyroid gland in male and female rats and male mice.

• Do not take ginkgo in case of hypersensitivity
• Avoid ginkgo before surgery; may increase the risk of bleeding. A study recommended discontinuation of ginkgo at least 36 hours before a surgical procedure
• Avoid use of ginkgo if you are attempting to get pregnant
• Ginkgo toxin is mostly in the seeds and fruit pulp, but some amount is also present in the leaves
• Use with caution if you are on non-steroidal anti-inflammatory drugs (NSAIDs), anticoagulant or anti-platelet therapy
• Use with caution in patients with epilepsy, may decrease seizure threshold
• Ginkgo can precipitate serotonin syndrome, a serious drug reaction, in patients on antidepressant medications
• Use with caution in diabetic patients, ginkgo may increase blood glucose levels

Common side effects of Ginkgo biloba include:

• Gastrointestinal upset
• Nausea
• Vomiting
• Constipation
• Diarrhea
• Headache
• Weakness
• Dizziness
• Vertigo (rare)
• Restlessness
• Seizures
• Palpitations
• Allergic skin reactions
• Contact dermatitis (topical use)
• Impaired fertility
• Allergic skin reactions
• Bleeding disorders
• Bleeding in the space between the brain and its protective membrane (subdural hematoma)
• Cases of spontaneous bleeding from the iris when used with aspirin have been reported
• Serotonin syndrome in individuals on SSRI antidepressants
• Increase in blood sugar

This is not a complete list of all side effects or adverse reactions that may occur from the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may also report side effects or health problems to the FDA at 1-800-FDA-1088.

Adult

There is no standard dose of Ginkgo biloba supplements. The suggested doses of leaf extract standardized to 24% flavonoids, 6% terpenes

Altitude Sickness Prevention

• 80 mg taken orally two times daily

Cognitive Function

• 120-240 mg taken orally once daily

Dementia

• 120-240 mg taken orally in divided doses two to three times daily

Intermittent Claudication

• 120-240 mg taken orally in divided doses two to three times daily

Premenstrual Syndrome

• 80 mg taken orally two times daily; start on day 16 and continue until day 5 of next cycle

SSRI-induced Sexual Dysfunction

• 60-240 mg taken orally two times daily

Vertigo/Tinnitus

• 120-160 mg/d taken orally in divided doses two to three times daily

Raynaud's Disease

• 360 mg/d taken orally in divided doses three times daily

Normal-Tension Glaucoma

• 40 mg taken orally three times daily for 4 weeks

Pediatric

There is insufficient evidence to recommend the use of ginkgo biloba in children

• Ginkgo biloba toxicity can cause bleeding, seizures and serotonin syndrome.
• There is no antidote for ginkgo biloba and treatment includes discontinuation of ginkgo and symptomatic therapy.

Inform your doctor of all medications you are currently taking, who can advise you on any possible drug interactions. Never begin taking, suddenly discontinue, or change the dosage of any medication without your doctor’s recommendation.

• There are no known severe reactions from the use of Ginkgo biloba.
• There are no known serious reactions from the use of Ginkgo biloba.
• Ginkgo Biloba has known moderate interactions with at least 75 different drugs.
• Mild interactions include:
  • anamu
  • cilostazol
  • clopidogrel
  • devil's claw
  • dipyridamole
  • eptifibatide
  • green tea
  • prasugrel
  • ticlopidine
  • tirofiban

The drug interactions listed above are not all of the possible interactions or adverse effects. For more information on drug interactions, visit the RxList Drug Interaction Checker.

It is important to always tell your doctor, pharmacist, or health care provider of all prescription and over-the-counter medications you use, as well as the dosage for each, and keep a list of the information. Check with your doctor or health care provider if you have any questions about the medication.

There are no data available about ginkgo biloba use in pregnancy or nursing mothers; avoid use.

• Ginkgo biloba is one of the most commonly used dietary supplements in the United States. In general, Ginkgo is safe, however, it must be used with caution because of side effects and interactions with other medications and dietary supplements.
• Dietary supplements do not require extensive pre-marketing approval from the FDA and there may sometimes be discrepancy between the labeling and the actual ingredients and their amounts.