The Triple Antigen Injection (Diphtheria toxoid, Pertussis toxoid, and Tetanus toxoid) protects individuals, especially children, from three serious diseases: diphtheria, pertussis (whooping cough), and tetanus. This vaccine is part of routine childhood immunisation schedules, with booster doses recommended for ongoing protection. Triple Antigen Injection works by introducing inactivated toxins that cause these diseases, prompting the immune system to produce antibodies without causing illness. If the body encounters the actual bacteria later, the immune system can fight off the infection more effectively. Common side effects include pain, redness, or swelling at the injection site, fever, irritability, fatigue, loss of appetite, and mild rash. While most side effects resolve on their own, certain precautions must be followed. Do not administer Triple Antigen Injection to anyone with a known allergy to its components or a history of severe allergic reactions (anaphylaxis) to previous doses. Use caution in individuals with a history of neurological disorders or severe reactions to the pertussis component. Avoid giving the vaccine during pregnancy unless absolutely necessary, as its safety has not been fully established. The vaccine should also not be given during moderate or severe acute illness, and care is needed when administering it to premature infants due to the risk of apnea (temporary cessation of breathing).