What are the side effects of the hepatitis A vaccine?

Side effects of the hepatitis A vaccine may include redness, swelling, or pain at the injection site, which typically resolve spontaneously. Some individuals may experience systemic side effects, such as dizziness, generalized fatigue, or low-grade fever; these symptoms usually subside gradually with adequate rest. Rarely, allergic reactions may occur—such as vomiting, nausea, palpitations, or pallor—and antiallergic medications (e.g., intramuscular diphenhydramine) may be administered per physician’s instructions.