Syncope or near-syncope occur with some frequency following vaccination. A sudden syncopal episode can result in traumatic injury which can be serious.


Types of injuries:

(1) head injury after hitting things while falling to the ground

(2) falling down steps

(3) automobile accidents


The risk is primarily seen in patients who have had an injection. An oral or intranasal vaccine should have a minimal risk of syncope.


About a third of syncopal episodes occur in pediatric patients from 10 to 18 years of age, especially females.


Almost two thirds of events occur within the first 5 minutes after the vaccination and almost 90% occur within 15 minutes.



(1) Have the person sit and wait for 15 minutes following the vaccination. Ideally the location should be free of hard corners or other potential sites of injury.

(2) Observe the patients for signs of impending syncope such as pallor, sweating, swaying, or complaints of dizziness. If signs occur have the person lie down immediately.

(3) If the person faints or has presyncopal symptoms, then continue to observe until after the symptoms completely resolve.

(4) A person with a history of syncopal episodes after a vaccination should be observed more closely.


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