What symptoms are commonly associated with vaccines administered orally?

• A. Headache and dizziness
• B. Rash at injection site
• C. Runny nose
• D. Nausea, vomiting, diarrhea

Answer: (D)

When a vaccine is given by mouth, it engages the gut’s mucosal immune system. Because the antigen passes through and often acts in the digestive tract, mild gastrointestinal upset can occur. Nausea, vomiting, and diarrhea reflect this direct GI exposure and, in the case of live attenuated oral vaccines like rotavirus, can be a common, expected side effect. Other symptoms like a rash at an injection site or a runny nose are more typical of vaccines given by injection or other routes, not of the oral route. So the most typical adverse effects linked to oral vaccines are gastrointestinal: nausea, vomiting, and diarrhea.