Q: Can chickenpox fever last for several days with temperatures reaching 39°C, and does my child need a fever-reducing injection?
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 child had mild cold symptoms for two weeks, and then on Sunday evening, developed a high fever that spiked to 39.7°C (103.5°F) overnight. On Monday, small blisters appeared, but a clinic initially diagnosed it as a viral rash. The fever hit 39.8°C again that night. On Tuesday, a different clinic confirmed it was chickenpox. We are using the prescribed medications, but the fever is still hovering around 39°C (102.2°F). Can a chickenpox fever last this long, and should we visit the clinic tomorrow to get a fever-reducing injection?
Answer:
It is understandable to be concerned when your child continues to run a high fever after several days of illness.
Chickenpox and Fever Duration
During the early stage of chickenpox, fevers ranging from 38°C to 39°C (100.4°F to 102.2°F) are common. However, the fever typically begins to decline within 1 to 2 days after the blisters fully emerge. If a high fever of 39°C or above persists past the third day of the rash, the primary concern shifts from the chickenpox virus itself to a secondary bacterial infection (such as a bacterial skin infection from scratching, or pneumonia).
When to Seek Immediate Medical Evaluation
Take your child to an urgent care clinic or emergency room immediately if you observe any of the following signs:
Redness, swelling, increased warmth, or pus spreading around the blisters
Worsening cough, rapid breathing, or difficulty breathing
Extreme lethargy, excessive sleepiness, or difficulty waking up
Signs of dehydration, such as no urination for 8 hours or dry mouth
Severe headache, neck stiffness, or persistent vomiting
Home Care and Medication Safety
Fever Reducers: Acetaminophen is the preferred medication for chickenpox.
Warning on Aspirin: Never give aspirin to children or teenagers with chickenpox, as it can cause Reye’s syndrome, a rare but life-threatening condition.
Caution with Ibuprofen: Nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen should generally be avoided or used with caution during chickenpox, as some studies suggest they may increase the risk of severe secondary bacterial skin infections.
Hydration: Offer small sips of water, oral rehydration solutions, or clear fluids every 5 to 10 minutes.
Skin Care: Keep fingernails trimmed short, use soft cotton mittens if needed, and apply cool, damp cloths to soothe itching (pat gently rather than rubbing).
Regarding Fever-Reducing Injections
An antipyretic injection only lowers body temperature temporarily; it does not treat the underlying cause of the fever. Rather than focusing on suppressing the fever with an injection, the priority is to identify why the high fever is persisting.
Recommended Next Steps
Have your child evaluated in person by a pediatrician or at an urgent care clinic. Let the physician know that the 39°C fever has persisted for three days despite the rash appearing, so they can closely examine the skin, lungs, and overall hydration status to rule out secondary bacterial complications that may require antibiotic therapy.
For extra peace of mind and clear guidance when tracking your child's symptoms, the FeverCoach app is always there to help.
