Despite the positive health claims concerning ginkgo biloba, it is however important to note that using the plant extract can have side effects such as: Headaches Upset stomach Dizziness Constipation  Allergic skin reactions Heart palpitations Early labor or extra bleeding during delivery if used by pregnant women Increased risk of bleeding (people taking blood thinners or anticoagulants should not take Ginkgo biloba. If you are expecting surgery, stop using Ginkgo biloba two weeks before the surgery). May interfere with the management of diabetes and seizure medication.