In recent years, biological therapy has been sought to treat a variety of diseases ranging from autoimmune and allergies to infections and malignancies. Biological therapy, also known as biotherapy or immunotherapy, is a type of treatment that uses laboratory-manufactured or naturally occurring agents derived from living organisms. Biological therapy is designed to target specific molecules or cells that are involved in disease processes. For example, monoclonal antibodies can be engineered to bind to specific proteins on cancer cells, while cell-based therapies can be customized to target specific types of immune cells. Biological therapies can target molecular pathways that were previously difficult to treat with traditional therapies. An example is Infliximab which acts as an antagonist to excess tumor necrosis factor alpha in rheumatoid arthritis. Although having far-reaching positive outcomes, side effects are not uncommon. Since the oral mucosa often reflects the body’s defense system as a whole, it’s normal for secondary effects to arise in the oral cavity. Adverse drug reactions are prevalent and may express themselves in a wide array of clinical manifestations. Patients undertaking this type of treatment have reported to experience xerostomia and mucositis as the most occurring ramification of biotherapy. Pemphigoid, Lichen Planus, dysesthesia, infections, erythema multiforme, osteonecrosis of the jaws and many others have also been documented. More studies and research on the risks, clinical diagnostic procedures, and treatment strategies are expected to emerge as these drugs become more widely employed. Doctors and patients must be made aware of the potential adverse effects that may occur. It is essential to have access to the appropriate knowledge, attitude, and mindset in order to help and support patients going through various types of side effects.