Q: My elementary school child vomited after receiving the flu vaccine. Is this a normal side effect, and can we just observe at home?
Medically reviewed by Sang Hyun Ahn, MD
Content edited by Myeongchan Kim, MD
This post is a dramatization of a question and answer session experienced by our actual medical reviewers. Please note that this content is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare professional for any health concerns or before making any decisions related to your health or treatment.
Question:
My elementary school-aged child received a flu vaccine around 4:00 PM today. By 6:00 PM, they complained of feeling exhausted and sleepy. After eating dinner and lying down, they vomited around 9:00 PM. They have now fallen asleep. Is it safe to just watch them overnight? I read that this can be a side effect, but we have never experienced vomiting after a vaccine before, so I am quite worried.
Answer:
Experiencing vomiting after a vaccination can certainly be alarming.
While common flu shot side effects include soreness at the injection site, low-grade fever, and mild body aches, systemic reactions such as fatigue, nausea, and vomiting can occasionally occur in children. The fact that your child is currently resting and sleeping peacefully is generally a reassuring sign.
Here is what you should do at home tonight:
Check responsiveness periodically: Gently wake your child every 2 to 3 hours to verify that they respond appropriately (e.g., they open their eyes, make eye contact, and answer when their name is called).
Provide small amounts of fluids: If they wake up and feel thirsty, offer small sips of water or an oral rehydration solution slowly. Do not force them to drink large amounts at once.
Position them on their side: Have your child sleep on their side rather than flat on their back to prevent choking or aspiration in the event that they vomit again while asleep.
Monitor hydration: Keep track of their urine output. If they go longer than 8 hours without urinating, it may be a sign of dehydration.
When to seek immediate emergency medical care:
Take your child to the nearest emergency room or pediatric urgent care center immediately if you observe any of the following warning signs:
They are difficult to wake up, unusually lethargic, or slow to respond.
Persistent, repeated vomiting where they cannot keep fluids down.
Signs of dehydration (e.g., parched lips/dry mouth, sunken eyes, no urination for more than 8 hours).
Signs of an allergic reaction, such as shortness of breath, wheezing, hives, or swelling of the face, lips, or tongue.
A high fever accompanied by a stiff neck or severe headache.
If your child rests well through the night and feels better by morning, call the clinic or pediatrician where the vaccine was administered to report the reaction and discuss whether any follow-up care is necessary.
For extra peace of mind and clear guidance when tracking your child's symptoms, the FeverCoach app is always there to help.
