Introduction

Herbal medications come from various types of plant sources that are used for prevention and/or treatment of diseases and other medical conditions. Records show that natural plant products have been employed throughout human history for therapeutic purposes, in most cases as a major form of therapy for millions of people worldwide. In many parts of the world, medicinal plant substances are recognized as herbal supplements and/or traditional medicines. However, products made from plant derivatives as purified chemical ingredients and subjected to scrutiny by official regulatory mechanisms are not considered as either herbal supplements or traditional medicines [1].

It is documented that more than 30% of the FDA-approved drugs currently in use were derived from plant sources and some of the commonly used drugs include aspirin, atropine, pilocarpine, morphine, lidocaine, quinidine, capsaicin, paclitaxel, reserpine, tubocurarine, and vincristine [1]. Besides being the origin of useful drug compounds, many other plant-based medicinal products are also known to be widely used, without official recognition or the need for prescriptions. Some of these natural products are supported scientifically for therapeutic usefulness, with the potential to be developed as drugs. Examples of such products include plant-based functional foods with anticancer properties [2], crude plant ingredients with the potential to prevent cardiovascular diseases [3], herbal preparations demonstrating effectiveness against neurological disorders [4], and plants and mushrooms having antiobesogenic and antidiabetic activities [5]. Despite these beneficial aspects, however, medicinal plant recipes are also associated with a number of adverse effects which can be of intrinsic or extrinsic origin [1].

The main objective of this review paper is to identify and review the commonly used herbal supplements in the USA that have the potential to interfere with blood clotting under dental settings. The dental implications of the use of these natural products are discussed along with recommendations for predictive and preventive measures to avoid/minimize the risk of bleeding. These herbal supplements were selected based on recent market-survey data and published information on utilization of supplements by US consumers [6-10].

Herbal supplements in the USA are manufactured products made from different parts of plants that are claimed to have medicinal properties [1, 9, 11]. These products are highly concentrated and have greater biological effects relative to respective raw material sources. Herbal supplements in the USA are a component of what are collectively known as dietary supplements within the realm of complementary and alternative medicine [1, 9, 11]. As such, the products are intended to be taken orally and can be obtained by consumers without prescriptions. As defined by the US Dietary Supplement Health and Education Act (DSHEA), herbal supplements are not classified as drugs, nor are they intended for use as food. Therefore, these products are used without being regulated with the same scrutiny as conventional drugs, although they may be subjected to certain limited regulatory measures. Herbal supplements are thus marketed in USA largely with no proven assurance for safety and efficacy, the burden of proof for safety lying on the regulatory authority [1, 9, 11].

A number of recent surveys have shown that the use of herbal supplements in the USA has markedly increased in the past three decades, despite the noted regulatory limitations. For instance, national telephone surveys conducted by the National Center for Health Statistics revealed that 2.2% adult Americans in the general population used these products in 1990 [12], while 18.8% used in 2002 [13]. Furthermore, a 2015 publication based on a nationwide survey reported that approximately 35% adult Americans use herbal supplements mostly on regular basis [14]. Depending upon specific circumstances, even greater utilization of these products has been observed among the elderly and medically compromised individuals [15-18]. Consistent with these reports, sales of herbal supplements in the US rose to $7.5 billion in 2016, with the market growing at about 8% per year [10].

In view of the growing use of herbs in the USA, it is likely that health care practitioners, including dentists, would see an increasing number of patients who take these products. It has been documented that as many as 70% of patients who take herbal supplements are unaware of their potential adverse effects and do not inform their health care providers about the use of these products [19]. Although the supplements are used with expectation of health benefits, with no proven effectiveness and safety, it has become increasingly clear that at least a portion the products cause adverse effects that may outweigh the benefits [1, 20]. As with most conventional drugs, the adverse effects of herbs may not only be limited to minor and predictable problems, but may also include effects that are more serious, uncommon, and unpredictable. These effects have been shown to be related partly to the way the products are manufactured and regulated, and to the lack of sufficient awareness on the part of many patients and even health care givers about the health issues associated with the products [1, 9, 20].

Information for the present review was collected from peer-reviewed journal articles, books, and other relevant resources. Besides using hard copy materials as sources of information, PubMed/Medline and Google searches were extensively made to access computer-generated information using the following specific search terms: herbal supplements, herbal medicines, herb-drug interactions, antiplatelet herbs, anticoagulant herbs, fibrinolytic herbs, oral health, dental effects, bleeding, blood clotting, adverse effects of herbs, toxicity of herbs, and herbal interaction with conventional drugs.