Who should not take Ginkgo biloba

Ginkgo biloba is sold freely, so many people perceive it as a remedy safe for everyone. However, there are conditions and situations in which taking ginkgo is inappropriate or dangerous, and most of them are related to the blood-clotting system, the nervous system and interaction with medications. The editorial team has systematized absolute and relative contraindications, relying on the European monograph and clinical data.

Absolute contraindications

Absolute contraindications are situations in which taking ginkgo is not allowed at all. For the standardized leaf extract there are few of them, but they are clearly defined in official documents.

The first is hypersensitivity to ginkgo or any component of the product. People who have had an allergic reaction to ginkgo preparations or contact dermatitis from the tree's fruit should refrain from taking it. A repeated reaction may be stronger.

The second is pregnancy. The European monograph classifies it as a contraindication. The reason is the theoretical effect on blood clotting, which may increase the risk of bleeding during childbirth, and the absence of safety studies. Breastfeeding is also not recommended due to a lack of data.

The third is established blood-clotting disorders and a tendency to bleeding, for example hemophilia or thrombocytopenia. For such people even a small additional effect on platelets can have serious consequences.

Medications with which ginkgo is incompatible or requires monitoring

The most significant group is drugs that affect blood clotting. Although meta-analyses have not confirmed a substantial effect of the standardized extract on clotting indicators in healthy people, in clinical cases of bleeding ginkgo was often combined precisely with such medications.

Interactions with antiretroviral agents, in particular efavirenz, are mentioned in the European monograph: ginkgo can reduce their concentration in the blood through an effect on liver enzymes. For drugs on which the control of a chronic infection depends, this is an unacceptable risk.

For antidepressants, drugs with a narrow therapeutic window and drugs metabolized by the CYP2C19 and CYP3A4 enzymes, the data are ambiguous. Reviews of pharmacokinetic interactions show that most of them are weak, but the individual reaction is unpredictable.

The rule is simple: if a person regularly takes any prescription drugs, the decision about ginkgo is made together with a doctor who knows the entire treatment regimen.

Conditions requiring special caution

In addition to absolute contraindications, there are situations in which intake is possible only after consulting a doctor and under monitoring. We call them relative contraindications.

• Epilepsy and a history of seizures.Isolated cases of seizures against the background of taking ginkgo have been described; the seeds contain ginkgotoxin, an antagonist of vitamin B6.
• A recent stroke, especially hemorrhagic.Any effect on blood clotting is assessed by a neurologist.
• Peptic ulcer disease, a history of gastrointestinal bleeding.
• Uncontrolled arterial hypertensionas an additional risk factor for hemorrhage.
• Severe liver and kidney diseases— safety data are insufficient.
• Diabetes on glucose-lowering therapy— an effect on glucose levels has been described in individual studies, monitoring is needed.

For each of these conditions the risk is not necessarily high, but the price of a mistake is great. Therefore, self-administration without a doctor's agreement is inappropriate here.

Elderly people are worth mentioning separately. It is they who most often take ginkgo "for memory" and at the same time most often receive aspirin, anticoagulants and other medications, which creates a risky combination.

Surgery, injuries and contact sports

Before any planned surgical intervention, including dental operations, ginkgo intake must be discussed with the surgeon and anesthesiologist. The discontinuation period is determined by the doctor, taking into account the type of operation and other medications.

For athletes in contact sports — martial arts, hockey, rugby — the effect on blood clotting has practical significance. Injuries with hematomas, cuts and nosebleeds are not uncommon here, so the advisability of taking ginkgo in such sports is doubtful, especially in the competitive period.

And if an athlete takes NSAID painkillers after injuries, combining them with ginkgo additionally increases the risk. This is one of the most common and least recognized combinations.

With any head injury or suspicion of internal bleeding, ginkgo should be discontinued and the doctor informed about its intake.

Children and adolescents

Data on the safety and efficacy of ginkgo in children and adolescents are insufficient, so the European monograph does not recommend use in persons under 18. The advice popular on the internet to give ginkgo to schoolchildren "for concentration" has no scientific basis.

For children, an additional risk is ginkgo seeds: it is precisely in children that the most severe ginkgotoxin poisonings with seizures have been described. If ginkgo trees grow nearby, it is worth explaining to children that the fruit and seeds must not be eaten.

Young athletes with problems of attention or fatigue need an examination, not herbal supplements. Behind these symptoms may lie lack of sleep, iron deficiency, overtraining or other conditions that require a completely different approach.

If ginkgo is already part of a complex product that an adolescent takes, this should be reported to the pediatrician.

Editorial conclusions

Ginkgo biloba is contraindicated in case of an allergy to it, during pregnancy and in blood-clotting disorders. Taking it together with anticoagulants, antiplatelet agents and some other medications is allowed only by a doctor's decision.

People with epilepsy, a recent stroke, peptic ulcer disease, as well as those preparing for surgery, should discuss intake with a doctor. Ginkgo is not recommended for persons under 18.

For athletes in contact sports and those who regularly take NSAIDs, the benefit of ginkgo is unlikely to outweigh the risks.

We also advise reading our articles "Side effects of Ginkgo biloba", "What to combine Ginkgo biloba with" and "How to take Ginkgo biloba: dosage, timing, duration".

References

1. European Medicines Agency, Committee on Herbal Medicinal Products (HMPC). European Union herbal monograph on Ginkgo biloba L., folium. London: EMA; 2015.
2. Bent S, Goldberg H, Padula A, Avins AL. Spontaneous bleeding associated with Ginkgo biloba: a case report and systematic review of the literature. J Gen Intern Med. 2005;20(7):657–661.
3. Kellermann AJ, Kloft C. Is there a risk of bleeding associated with standardized Ginkgo biloba extract therapy? A systematic review and meta-analysis. Pharmacotherapy. 2011;31(5):490–502.
4. Unger M. Pharmacokinetic drug interactions involving Ginkgo biloba. Drug Metab Rev. 2013;45(3):353–385.
5. Leistner E, Drewke C. Ginkgo biloba and ginkgotoxin. J Nat Prod. 2010;73(1):86–92.
6. DeKosky ST, Williamson JD, Fitzpatrick AL, et al. Ginkgo biloba for prevention of dementia: a randomized controlled trial. JAMA. 2008;300(19):2253–2262.