Areca nut (AN) is one of the addictive substances consumed widely in the world. The composition of AN is very complex, and each component has variable properties. This study aims to review the composition of AN and its adverse effects on humans. For this review, the literature search was performed by an electronic search of the Pubmed/Medline, Scopus, and Google Scholar databases using proper MESH headings and retrieved the articles published from 1997 to 2022. The eligibility criteria included human studies, a form of AN, the composition of AN, harmful effects of AN, the effect of AN on the oral cavity, the effect of AN on vital organs, and articles published in English. Data were extracted regarding the composition of AN, forms of AN, and harmful effects of AN on the oral cavity and on other systems. A total of 449 articles were identified from various databases, and 36 studies were selected that met the inclusion criteria. The active components of AN, which produce harmful effects, are primarily alkaloids, polyphenols, tannins, and certain trace elements. AN is consumed in different forms, and based on the form, its composition also varies. AN is known to cause deleterious effects on the oral cavity as well as various body organs. The most dangerous and widely reported impacts of AN on the oral cavity are the development of oral submucous fibrosis, a premalignant condition, and oral malignancy. However, during the chewing process, excretory products of AN are released and circulate in the body of "chronic habitual" and affect the other body parts. Thus, AN consumption may contribute to cardiac, liver, endocrinal, metabolic, respiratory, and reproductive system disorders also. AN composition is complex, and its consumption is harmful to human health. In regard to controlling the issue of the harmful effects of this habit, preventive measures should be established.