Effects of Anti-D Injection

Anti-D contains antibodies that help prevent your immune system from making antibodies against rhesus-positive blood cells. It may be offered during pregnancy or after an event where fetal and maternal blood could mix, such as bleeding, abdominal injury, a procedure, or birth. A tender arm, mild swelling, headache, or a general feeling of being unwell can occur after the dose. These effects usually settle without treatment. The injection does not treat every cause of bleeding or pain, so the pregnancy event itself still needs appropriate assessment.

Keep the injection area clean and notice whether redness, swelling, or discomfort is changing. Rest if you feel unwell and use only a pain reliever that your maternity team says is suitable for you. Keep any follow-up appointment, because Anti-D may be needed at specific stages or after new bleeding or injury. Tell your clinician about previous reactions, allergies, or medicines before another dose. Read more about [Anti-D Immunoglobulin](/materials/anti-d-immunoglobulin/) and [Anti-D Injection](/treatments/pregnancy-and-birth-care/anti-d-injection/).

Contact your maternity unit promptly for heavy or continuing vaginal bleeding, worsening abdominal pain, regular contractions, fluid leaking, reduced fetal movement, fever, or feeling faint. Seek emergency help for trouble breathing, swelling of the lips or face, widespread hives, collapse, or rapidly worsening illness after the injection. A sore arm alone is usually not an emergency, but severe pain, spreading redness, or pus should be checked.

Ask why Anti-D is recommended in your situation, when its protection is expected to begin, whether another dose may be needed, and which symptoms should take you directly to urgent care.