Ginkgo biloba has been around for roughly 270 million years, making it one of the oldest living tree species on earth. It survived whatever killed the dinosaurs, which is more than most plants can claim. Traditional Chinese medicine has used ginkgo leaves for centuries, though the modern standardised extract (known as EGb 761) only dates back to the 1960s in Germany.

The extract contains two main active components: flavonoid glycosides (around 24%) and terpene lactones (about 6%), including ginkgolides and bilobalide. These compounds appear to have antioxidant properties, reduce inflammation, improve blood flow, and affect platelet aggregation. Whether these mechanisms translate into meaningful clinical benefits is where things get complicated.

What the research actually shows

I should be upfront: ginkgo research is a mixed bag. Some studies show genuine promise, particularly for dementia and circulation problems. Others show essentially nothing. Part of the problem is that many trials were small, poorly designed, or funded by supplement manufacturers. The better-quality studies tend to show more modest effects.

Here’s what we know from the more rigorous research.

Benefits with reasonable evidence

Dementia and Alzheimer’s disease

This is probably ginkgo’s best-studied use. A meta-analysis of seven double-blind randomised controlled trials involving 939 Alzheimer’s patients found that EGb 761 improved cognitive function and overall clinical assessments compared to placebo 1. The effect sizes weren’t dramatic, but they were statistically significant and the safety profile was acceptable.

Another analysis of four trials with 1,628 patients found ginkgo helped with neuropsychiatric symptoms like depression, restlessness, anxiety, and sleep disturbances 2. Interestingly, it didn’t help with psychotic symptoms like delusions or hallucinations.

However, and this is important, ginkgo doesn’t appear to prevent dementia from developing in the first place. A large analysis of nearly 6,000 participants found no preventive effect 3. So if you’re already experiencing cognitive decline, it might help. If you’re trying to ward off future problems, the evidence doesn’t support that.

Related reading: Health foods beneficial to dementia

Stroke recovery

A systematic review of 13 randomised controlled trials involving 1,260 ischaemic stroke patients found that adding ginkgo preparations to standard treatment improved neurological function scores, daily living abilities, and blood flow markers 4.

The mechanism makes theoretical sense: ginkgo improves circulation and has neuroprotective properties. But the studies were generally small and had methodological limitations. I’d consider this promising rather than conclusive.

Sudden hearing loss

Sudden sensorineural hearing loss affects roughly 5 to 20 people per 100,000 annually. Standard treatment is corticosteroids, but adding ginkgo extract might boost recovery rates. A meta-analysis of 11 trials with 1,069 participants found improved clinical cure rates when ginkgo was combined with corticosteroids 5.

Again, study quality was variable, so take this with appropriate scepticism. But if you’ve experienced sudden hearing loss, it might be worth discussing with your ENT specialist.

Angina and cardiovascular support

Ginkgo appears to help with angina when combined with conventional medications. A meta-analysis of 41 trials covering 4,462 patients found that ginkgo damole injection plus standard drugs outperformed drugs alone 6. Treatment response rates improved, as did various blood viscosity markers.

The cardiovascular effects aren’t surprising given ginkgo’s blood-thinning and vasodilating properties. For related cardiovascular supplements, see our article on fish oil and CoQ10.

Vertebrobasilar insufficiency

This condition involves reduced blood flow to the brainstem and cerebellum, causing dizziness, vertigo, and balance problems. A review of 20 trials with 1,710 patients found ginkgo injections improved clinical response rates when added to standard treatment 7.

Tardive dyskinesia

Here’s an interesting one. Tardive dyskinesia is a movement disorder that can develop after long-term use of antipsychotic medications, affecting 20-30% of patients. A meta-analysis of three trials with 299 schizophrenia patients found that 240mg daily of ginkgo extract reduced symptom severity when added to medication 8.

The proposed mechanism involves ginkgo’s antioxidant properties and ability to increase brain-derived neurotrophic factor. This is one area where I’d say the evidence is reasonably encouraging.

Benefits with weaker or no evidence

Tinnitus

Despite ginkgo being heavily marketed for tinnitus, a Cochrane review of four trials with 1,543 participants found no significant benefit for primary tinnitus 9. The only exception was tinnitus associated with dementia, where small improvements were noted.

This is a good example of marketing outpacing evidence. If you have tinnitus, ginkgo probably isn’t your answer.

Memory in healthy people

“Brain boosters” are popular, but a meta-analysis of 10 studies with 2,576 healthy participants found ginkgo’s effect on memory, executive function, and concentration was essentially zero 10. The effect size didn’t change with age, dose, or duration.

So if you’re cognitively healthy and hoping ginkgo will sharpen your mind, don’t hold your breath.

Intermittent claudication

Claudication is leg pain during walking caused by peripheral artery disease. Given ginkgo’s circulation effects, you’d expect it to help. A Cochrane review of 14 trials with 739 patients found it increased walking distance by about 65 metres, but this wasn’t significantly different from placebo 11.

Altitude sickness

The evidence here is genuinely inconclusive. A meta-analysis of seven trials with 451 participants suggested ginkgo might have some protective effect against acute mountain sickness, but the result wasn’t statistically significant 12.

Side effects

Ginkgo extract is generally well tolerated at standard doses. Reported side effects include:

Gastrointestinal upset (nausea, diarrhoea, stomach pain)
Headache
Dizziness
Heart palpitations
Skin reactions
Constipation

These are typically mild and uncommon. The bigger concern is ginkgo’s blood-thinning effect, which can cause problems for certain people (see contraindications below).

Important warning about raw ginkgo: The seeds (fruit) contain toxins including 4’-methoxypyridoxine, which interferes with vitamin B6 metabolism, and cyanogenic glycosides. Eating raw seeds or too many cooked seeds can cause seizures, breathing difficulties, weak pulse, nausea, and confusion. Stick to standardised leaf extracts.

Who should avoid ginkgo (contraindications)

This is where I need to be quite detailed, because ginkgo interacts with numerous medications due to its effects on blood clotting and liver enzymes.

Absolutely avoid ginkgo if you:

Are trying to conceive, pregnant, or breastfeeding. Ginkgo may affect fertility, cause bleeding during labour, or pass into breast milk.
Have epilepsy or a seizure disorder. Ginkgo may lower the seizure threshold.
Have G6PD deficiency (favism). Ginkgo can trigger acute haemolytic anaemia 13.
Are allergic to poison ivy, poison oak, mango rind, or cashew shell oil. Cross-reactivity is possible.
Have surgery scheduled within two weeks. Stop ginkgo at least 14 days before any surgical procedure due to bleeding risk.

Use extreme caution or avoid if taking:

Blood thinners or antiplatelet drugs: aspirin, clopidogrel, warfarin, heparin, enoxaparin, dalteparin, diclofenac, ibuprofen, naproxen
Psychiatric medications: alprazolam, buspirone. Ginkgo may alter their effectiveness.
HIV medication efavirenz. Ginkgo may reduce drug levels.
The antidepressant trazodone. There’s a case report of coma 14.
St John’s wort combined with fluoxetine. This combination with ginkgo may trigger hypomania.
Medications metabolised by cytochrome P450 enzymes 15. This is a long list including:
- CYP1A2 substrates: clozapine, theophylline, olanzapine, propranolol
- CYP2C9 substrates: warfarin, celecoxib, losartan, phenytoin, tamoxifen
- CYP2C19 substrates: omeprazole, diazepam, citalopram
- CYP2D6 substrates: codeine, fluoxetine, metoprolol, tramadol, ondansetron
- CYP3A4 substrates: cyclosporine, statins (lovastatin), diltiazem, oestrogens
Diabetes medications: glimepiride, glyburide, insulin, pioglitazone, rosiglitazone. Ginkgo may affect blood sugar control.
Anti-seizure medications: phenobarbital, phenytoin, valproic acid, carbamazepine, gabapentin
The blood pressure medication hydrochlorothiazide. Paradoxically, this combination may raise blood pressure.
The proton pump inhibitor omeprazole
Any medication that lowers the seizure threshold (anaesthetics, some antibiotics, antidepressants, antihistamines, stimulants)

If you’re taking any prescription medication, check with your pharmacist before starting ginkgo. The cytochrome P450 interactions alone cover hundreds of drugs.

Dosage

Most clinical trials used standardised EGb 761 extract at 120-240mg daily, usually divided into two or three doses. Higher doses don’t appear to provide additional benefit and may increase side effects.

My overall take

Ginkgo biloba has genuine pharmacological activity, and for certain conditions, particularly dementia and some circulation problems, the evidence suggests modest benefits. For healthy people hoping to boost cognition, the research doesn’t support that use.

The biggest issue with ginkgo isn’t that it doesn’t work; it’s the extensive list of drug interactions. If you’re on multiple medications, especially blood thinners or psychiatric drugs, ginkgo could cause real problems. The blood-thinning effect that makes it potentially useful for circulation also makes it risky for many people.

If you’re considering ginkgo, have an honest conversation with your doctor or pharmacist about your complete medication list. And stick to reputable standardised extracts rather than random supplements, as quality control varies enormously in this industry.

For other supplements that support cognitive function and circulation, you might also explore vitamin B complex and alpha-lipoic acid.